Klinefelter's syndrome is a condition caused by a chromosomal abnormality in males; sufferers have a pair of X chromosomes instead of just one. The XXY chromosome arrangement is a common genetic abnormality, occurring as frequently as 1 in 1,000 male births, but the symptoms that may result from having the extra chromosome is less common. Because of this extra chromosome, individuals with the abnormality are usually referred to as "XXY Males" rather than as "suffering from Klinefelter's syndrome."

In mammals with more than one X chromosome, the genes on all but one X chromosome are barred from being expressed. This happens in XXY males as well as XX females. A few genes, however, have corresponding genes on the Y chromosome and are not barred. These triploid genes in XXY males may be responsible for the symptoms of Klinefelter's syndrome.

In adults, the syndrome is characterised by gynecomastia (enlarged breasts), a rounded body type with abnormal body proportions, sparse facial and body hair, small testes, and an inability to produce sperm. Most XXY males have some degree of language impairment as well. The syndrome is associated with an increased risk of breast cancer, pulmonary disease, varicose veins, and osteoporosis.

The condition was identified in 1942 by Dr. Harry Klinefelter in Boston. The cause was not found until the 1950s; the condition is incurable, but its symptoms can be treated in a number of ways, including testosterone treatment and other therapies.

Table of contents
1 External links
2 What is Klinefelter's Syndrom?
3 Chromosomes and Klinefelter syndrome
4 Causes
5 Diagnosis
6 What to tell families, friends and XXY boys
7 Childhood
8 Detecting language problems early
9 Guidelines for detecting language problems
10 The XXY boy in the classroom
11 Help under the law
12 Adolescence
13 Testosterone treatment
14 Chromosomal variations
15 Sexuality
16 Infertility
17 Health considerations
18 Adulthood

External links

The material below is taken from a 1993 public domain source, "Understanding Klinefelter Syndrome, A Guide for XXY Males and Their Families" by Robert Bock of the Office of Research Reporting, NICHD, NIH Pub. No. 93-3202 at http://www.nichd.nih.gov/publications/pubs/klinefelter.htm and should be merged into the article text above

What is Klinefelter's Syndrom?

In 1942, Dr. Harry Klinefelter and his coworkers at the Massachusetts General Hospital in Boston published a report about nine men who had enlarged breasts, sparse facial and body hair, small testes, and an inability to produce sperm.

By the late 1950s, researchers discovered that men with Klinefelter syndrome, as this group of symptoms came to be called, had an extra sex chromosome, XXY instead of the usual male arrangement, XY. (For a more complete explanation of the role this extra chromosome plays, see the accompanying section, "Chromosomes and Klinefelter syndrome.")

In the early 1970s, researchers around the world sought to identify males having the extra chromosome by screening large numbers of newborn babies. One of the largest of these studies, sponsored by the National Institute of Child Health and Human Development (NICHD), checked the chromosomes of more than 40,000 infants.

Based on these studies, the XXY chromosome arrangement appears to be one of the most common genetic abnormalities known, occurring as frequently as 1 in 500 to 1 in 1,000 male births. Although the syndrome's cause, an extra sex chromosome, is widespread, the syndrome itself-the set of symptoms and characteristics that may result from having the extra chromosome-is uncommon. Many men live out their lives without ever even suspecting that they have an additional chromosome.

" I never refer to newborn babies as having Klinefelter's, because they don't have a syndrome," said Arthur Robinson, M.D., a pediatrician at the University of Colorado Medical School in Denver and the director of the NICHD-sponsored study of XXY males. "Presumably, some of them will grow up to develop the syndrome Dr. Klinefelter described, but a lot of them won't."

For this reason, the term "Klinefelter syndrome" has fallen out of favor with medical researchers. Most prefer to describe men and boys having the extra chromosome as "XXY males."

In addition to occasional breast enlargement, lack of facial and body hair, and a rounded body type, XXY males are more likely than other males to be overweight, and tend to be taller than their fathers and brothers.

For the most part, these symptoms are treatable. Surgery, when necessary, can reduce breast size. Regular injections of the male hormone testosterone, beginning at puberty, can promote strength and facial hair growth-as well as bring about a more muscular body type.

A far more serious symptom, however, is one that is not always readily apparent. Although they are not mentally retarded, most XXY males have some degree of language impairment. As children, they often learn to speak much later than do other children and may have difficulty learning to read and write. And while they eventually do learn to speak and converse normally, the majority tend to have some degree of difficulty with language throughout their lives. If untreated, this language impairment can lead to school failure and its attendant loss of self esteem.

Fortunately, however, this language disability usually can be compensated for. Chances for success are greatest if begun in early childhood. Sections that follow describe possible strategies for meeting the special educational needs of many XXY males.

Chromosomes and Klinefelter syndrome

Chromosomes, the spaghetti-like strands of hereditary material found in each cell of the body, determine such characteristics as the color of our eyes and hair, our height, and whether we are male or female.

Women usually inherit two X chromosomes-one from each parent. Men tend to inherit an X chromosome from their mothers, and a Y chromosome from their fathers. Most males with the syndrome Dr. Klinefelter described, however, have an additional X chromosomes total of two X chromosomes and one Y chromosome.


No one knows what puts a couple at risk for conceiving an XXY child. Advanced maternal age increases the risk for the XXY chromosome count, but only slightly. Furthermore, recent studies conducted by NICHD grantee Terry Hassold, a geneticist at Case Western Reserve University in Cleveland, OH, show that half the time, the extra chromosome comes from the father.

Dr. Hassold explained that cells destined to become sperm or eggs undergo a process known as meiosis. In this process, the 46 chromosomes in the cell separate, ultimately producing two new cells having 23 chromosomes each. Before meiosis is completed, however, chromosomes pair with their corresponding chromosomes and exchange bits of genetic material. In women, X chromosomes pair; in men, the X and Y chromosome pair. After the exchange, the chromosomes separate, and meiosis continues.

In some cases, the Xs or the X chromosome and Y chromosome fail to pair and fail to exchange genetic material. Occasionally, this results in their moving independently to the same cell, producing either an egg with two Xs, or a sperm having both an X and a Y chromosome. When a sperm having both an X and a Y chromosome fertilizes an egg having a single X chromosome, or a normal Y- bearing sperm fertilizes an egg having two X chromosomes, an XXY male is conceived.


Because they often don't appear any different from anyone else, many XXY males probably never learn of their extra chromosome. However, if they are to be diagnosed, chances are greatest at one of the following times in life: before or shortly after birth, early childhood, adolescence, and in adulthood (as a result of testing for infertility).

In recent years, many XXY males have been diagnosed before birth, through amniocentesis or chorionic villus sampling (CVS). In amniocentesis, a sample of the fluid surrounding the fetus is withdrawn. Fetal cells in the fluid are then examined for chromosomal abnormalities. CVS is similar to amniocentesis, except that the procedure is done in the first trimester, and the fetal cells needed for examination are taken from the placenta. Neither procedure is used routinely, except when there is a family history of genetic defects, the pregnant woman is older than 35, or when other medical indications are present.

"If I were going to say something to parents who have had a prenatal diagnosis, it would be 'You are so lucky that you know," said Melissa, the mother of one XXY boy. "Because there are parents who don't know that their sons have this problem. And they will never be able to help them lead a normal life. But you can."

The next most likely opportunity for diagnosis is when the child begins school. A physician may suspect a boy is an XXY male if he is delayed in learning to talk and has difficulty with reading and writing. XXY boys may also be tall and thin and somewhat passive and shy. Again, however, there are no guarantees. Some of the boys who fit this description will have the XXY chromosome count, but many others will not.

A few XXY males are diagnosed at adolescence, when excessive breast development forces them to seek medical attention. Like some chromosomally normal males, many XXY males undergo slight breast enlargement at puberty. Of these, only about a third-10 percent of XXY males in all-will develop breasts large enough to embarrass them.

The final chance for diagnosis is at adulthood, as a result of testing for infertility. At this time, an examining physician may note the undersized testes characteristic of an XXY male. In addition to infertility tests, the physician may order tests to detect increased levels of hormones known as gonadotropins, common in XXY males.

A karyotype is used to confirm the diagnosis. In this procedure, a small blood sample is drawn. White blood cells are then separated from the sample, mixed with tissue culture medium, incubated, and checked for chromosomal abnormalities, such as an extra X chromosome.

What to tell families, friends and XXY boys

Expectant parents awaiting the arrival of their XXY baby have difficult choices to make: whom to tell-and how much to tell about their son's extra chromosome. Fortunately, however, there are some guidelines that new parents can take into account when making their decisions.

One school of thought holds that the best course is to go on slowly, waiting at least 1 year before telling anyone-grandparents included-about the child's extra chromosome. Many people are frightened by the diagnosis, and their fears will color their perceptions of the child. For example, some people may confuse the term Klinefelter syndrome with Down syndrome, a condition resulting in mild to moderate mental retardation.

Others may prefer to reveal the diagnosis early. Some parents have found that grandparents, aunts, uncles-and even extended family members-are more supportive when given accurate information. Another important decision parents must make is when to tell their son about his diagnosis. Some experts recommend telling the child early. When the truth is withheld, children often suspect that their parents are hiding something and may imagine a condition that is worse than their actual diagnosis.

This school of thought maintains that by the time he is 10 or 11 years old, the child can be told that his cells differ slightly from those of other people. Soon after, he can be filled in on the details: that the cell difference is due to an additional X chromosome, which is responsible for his undersized testes and any reading difficulties he may have. At this time, the child can be reassured that he does not have a disease and will not become sick. The child should also be told that some people may misunderstand this information and that he should exercise discretion in sharing it with others.

By roughly the age of 12, depending on the child's emotional maturity, he can be told that he will most probably be infertile. Parents should stress that neither the X chromosome nor the infertility associated with it mean that he is in any way less masculine than other males his age. The child's parents or his physician can explain that although he may not be able to make a baby, he can consider adopting one. Parents may also need to reassure an XXY boy that his small testes will in no way interfere with his ability to have a normal sex life.

Adherents of this school of thought believe that learning about possible infertility in such a gradual manner will be less of a shock than finding out about it all at once, late in the teen years.

Conversely, other experts believe that holding back the information does not appear to do any harm. Instead, telling an XXY boy about his extra chromosome too early may have some unpleasant consequences. An 11 or 12-year-old, for example, may associate infertility with sexual disorders and other concepts he may not yet understand.

Moreover, children, when making friends, tend to share secrets. But childhood friendships may be fleeting, and early confidences are sometimes betrayed. A malicious or thoughtless child may tell all the neighborhood children that his former companion is a "freak" because he has an extra chromosome.

For this reason, the best time to reveal the information may be mid-to-late adolescence, when an XXY male is old enough to understand his condition and better able to decide with whom he wishes to share this knowledge.


According to Dr. Robinson, the director of the NICHD-funded study, XXY babies differ little from other children their age. They tend to start life as what many parents call "good" babies-quiet, undemanding, and perhaps even a little passive. As toddlers, they may be somewhat shy and reserved. They usually learn to walk later than most other children, and may have similar delays in learning to speak.

In some, the language delays may be more severe, with the child not fully learning to talk until about age 5. Others may learn to speak at a normal rate, and not meet with any problems until they begin school, where they may experience reading difficulties. A few may not have any problems at all-in learning to speak or in learning to read.

XXY males usually have difficulty with expressive language the ability to put thoughts, ideas, and emotions into words. In contrast, their faculty for receptive language-understanding what is said-is close to normal.

"It's one of the conflicts they have," said Melissa, the mother of an XXY boy. "My son can understand the conversations of other 10 year olds. But his inability to use the language the way other 10-year olds use it makes him stand out."

In addition to academic help, XXY boys, like other language disabled children, may need help with social skills. Language is essential not only for learning the school curriculum, but also for building social relationships. By talking and listening, children make friends-in the process, sharing information, attitudes, and beliefs. Through language, they also learn how to behave-not just in the schoolroom, but also on the playground. If their sons' language disability seems to prevent them from fitting in socially, the parents of XXY boys may want to ask school officials about a social skills training program.

Throughout childhood-perhaps, even, for the rest of their lives-XXY boys retain the same temperament and disposition they first displayed as infants and toddlers. As a group, they tend to be shy, somewhat passive, and unlikely to take a leadership role. Although they do make friends with other children, they tend to have only a few friends at a time. Researchers also describe them as cooperative and eager to please.

Detecting language problems early

The parents of XXY babies can compensate for their children's language disability by providing special help in language development, beginning at an early age. However, there is no easy formula to meet the language needs of all XXY boys. Like everyone else, XXY males are unique individuals. A few may not have any trouble learning to read and write, while the rest may have language impairments ranging from mild to severe.

If their son's speech seems to be lagging behind that of other children, parents should ask their child's pediatrician for a referral to a speech pathologist for further testing. A speech pathologist specializes in the disorders of voice, speech, and language. (The American Speech, Language and Hearing Association, listed in the reference section, distributes a free pamphlet on the stages of language development during the first 5 years of life.)

Parents should also pay particular attention to their children's hearing. Like other small children, XXY infants and toddlers may suffer from frequent ear infections. With any child, such infections may impair hearing and delay the acquisition of language. Such a hearing impairment may be a further setback for an XXY child who is already having language difficulties.

Guidelines for detecting language problems

Shortly after the first birthday, children should be able to make their wishes known with simple one word utterances. For example, a child may say "milk" to mean "I want more milk." Gradually, children begin to combine words to produce two-word sentences, such as "More milk." By age three, most children use an average of about four words per sentence.

If a child is not communicating effectively with single words by 18 to 24 months, then parents should seek a consultation with a speech and language pathologist.

The XXY boy in the classroom

Although there are exceptions, XXY boys are usually well behaved in the classroom. Most are shy, quiet, and eager to please the teacher. But when faced with material they find difficult, they tend to withdraw into quiet daydreaming. Teachers sometimes fail to realize they have a language problem, and dismiss them as lazy, saying they could do the work if they would only try. Many become so quiet that teachers forget they're even in the room. As a result, they fall farther and farther behind, and eventually may be held back a grade.

Help under the law

According to Dr. Robinson, XXY boys do best in small, uncrowded classrooms where teachers can give them a lot of individual attention. He suggests that parents who can meet the expense consider sending their sons to a private school offering special educational services.

Parents who cannot afford private schools should become familiar with Public Law 94-142, the Education of the Handicapped Act-now called the Individuals with Disabilities Education Act. This law, adopted by Congress in 1975, states that all children with disabilities have a right to a free, appropriate public education. The law cannot ensure that every child who needs special educational services will automatically get them. But the law does allow parents to take action when they suspect their child has a learning disability.

Chances for success are greatest for parents who are well informed and work cooperatively with the schools to plan educational and related service programs for their sons. For in-depth information on Public Law 94-142, parents may contact the National Information Center for Children and Youth with Disabilities (NICHCY), listed in the Resources section.

Parents may also wish to contact their local and state boards of education for information on how the law has been implemented in their area. In addition, local educational groups may be able to provide useful information on working with school systems. Parents should also consider taking a course in educational advocacy. The local public school system, the state board of education, or local parents groups may be able to tell parents where they can enroll in such a course.

For information on learning disabilities, parents can contact the Learning Disabilities Association of America and the Orton Dyslexia Society, both listed in the reference section.

Services for infants, toddlers and pre-schoolers

The chances for reducing the impact of a learning disability are greatest in early childhood. Public Law 99-457 is an amendment to Public Law 94-142 that assists states in providing special educational services for infants, toddlers, and preschoolers. Eligibility requirements and entrance procedures vary from state to state. To learn the agencies to contact in their area, parents may call the Federation for Children with Special Needs (listed in the Resources section). The NICHCY (also listed in the Resources section) distributes the brochure "A Parent's Guide to Accessing Programs for Infants, Toddlers, and Preschoolers with Handicaps."


In general, XXY boys enter puberty normally, without any delay of physical maturity. But as puberty progresses, they fail to keep pace with other males. In chromosomally normal teenaged boys, the testes gradually increase in size, from an initial volume of about 2 ml, to about 15 ml. In XXY males, while the penis is usually of normal size, the testes remain at 2 ml, and cannot produce sufficient quantities of the male hormone testosterone. As a result, many XXY adolescents, although taller than average, may not be as strong as other teenaged boys, and may lack facial or body hair.

As they enter puberty, many boys will undergo slight breast enlargement. For most teenaged males, this condition, known as gynecomastia, tends to disappear in a short time. About one-third of XXY boys develop enlarged breasts in early adolescence slightly more than do chromosomally normal boys. Furthermore, in XXY boys, this condition may be permanent. However, only about 10 percent of XXY males have breast enlargement great enough to require surgery.

Most XXY adolescents benefit from receiving an injection of testosterone every 2 weeks, beginning at puberty. The hormone increases strength and brings on a more muscular, masculine appearance. More information about testosterone and XXY males can be found in the section titled "Testosterone Treatment."

Adolescence and the high school years can be difficult for XXY boys and their families, particularly in neighborhoods and schools where the emphasis is on athletic ability and physical prowess.

"They're usually tall, good-looking kids, but they tend to be awkward," Dr. Robinson said of the XXY teenagers he has met through his study. "They don't necessarily make good football players or good basketball players."

Lack of strength and agility, combined with a history of learning disabilities, may damage self-esteem. Unsympathetic peers, too, sometimes may make matters worse, through teasing or ridicule.

"Lots of kids have a tough time during adolescence," Dr. Robinson said. "But a higher proportion of XXY boys have a tough time. High school is very competitive, and these kids are not very good competitors, in general."

Dr. Robinson again stressed, however, that while XXY males share many characteristics, they cannot be pigeonholed into rigid categories. Several of his patients have played football, and one, in particular, is an excellent tennis player.

Damage to self esteem may be more severe in XXY teenagers who are diagnosed in early or late adolescence. Teachers-and even parents-may have dismissed their scholastic difficulties as laziness. Lack of athletic prowess and the inability to use language properly in social settings may have helped to isolate them from their peers. Some may react by sliding quietly into depression and withdraw from contact with other people. Others may find acceptance in a dangerous crowd.

For these reasons, XXY males diagnosed as teenagers may need psychological counseling as well as help in overcoming their learning disabilities. Help with learning disabilities is available through public school systems for XXY males high-school age and under. Referrals to qualified mental health specialists may be obtained from family physicians.

Testosterone treatment

Ideally, XXY males should begin testosterone treatment as they enter puberty. XXY males diagnosed in adulthood are also likely to benefit from the hormone. A regular schedule of testosterone injections will increase strength and muscle size, and promote the growth of facial and body hair.

In addition to these physical changes, testosterone injections often bring on psychological changes as well. As they begin to develop a more masculine appearance, the self-confidence of XXY males tends to increase. Many become more energetic and stop having sudden, angry changes in moods. What is not clear is whether these psychological changes are a direct result of testosterone treatment or are a side benefit of the increased self confidence that the treatment may bring. As a group, XXY boys tend to suffer from depression, principally because of their scholastic difficulties and problems fitting in with other males their age. Sudden, angry changes in mood are typical of depressed people.

Other benefits of testosterone treatment may include decreased need for sleep, an enhanced ability to concentrate, and improved relations with others. But to obtain these benefits an XXY male must decide, on his own, that he is ready to stick to a regular schedule of injections.

Sometimes, younger adolescents, who may be somewhat immature, seem not quite ready to take the shots. It is an inconvenience, and many don't like needles.

Most physicians do not push the young-men to take the injections. Instead, they usually recommend informing XXY adolescents and their parents about the benefits of testosterone injections and letting them take as much time as they need to make their decision.

Individuals may respond to testosterone treatment in different ways. Although the majority of XXY males ultimately will benefit from testosterone, a few will not.

To ensure that the injections will provide the maximum benefit, XXY males who are ready to begin testosterone injections should consult a qualified endocrinologist (a specialist in hormonal interactions) who has experience treating XXY males.

Side effects of the injections are few. Some individuals may develop a minor allergic reaction at the injection site, resulting in an itchy welt resembling a mosquito bite. Applying a non-prescription hydrocortisone cream to the area will reduce swelling and itching.

In addition, testosterone injections may result in a condition known as benign prostatic hyperplasia (BPH). This condition is common in chromosomally normal males as well, affecting more than 50 percent of men in their sixties, and as many as 90 percent in their seventies and eighties. In XXY males receiving testosterone injections, this condition may begin sometime after age 40.

The prostate is a small gland about the size of a walnut, which helps to manufacture semen. The gland is located just beneath the bladder and surrounds the urethra, the tube through which urine passes out of the body.

In BPH, the prostate increases in size, sometimes squeezing the bladder and urethra and causing difficulty urinating, "dribbling" after urination, and the need to urinate frequently.

XXY males receiving testosterone injections should consult their physicians about a regular schedule of prostate examinations. BPH can often be detected early by a rectal exam. If the prostate greatly interferes with the flow of urine, excess prostate tissue can be trimmed away by a surgical instrument that is inserted in the penis, through the urethra.

Chromosomal variations

Occasionally, variations of the XXY chromosome count may occur, the most common being the XY/XXY mosaic. In this variation, some of the cells in the male's body have an additional X chromosome, and the rest have the normal XY chromosome count. The percentage of cells containing the extra chromosome varies from case to case. In some instances, XY/XXY mosaics may have enough normally functioning cells in the testes to allow them to father children.

A few instances of males having two or even three additional X chromosomes have also been reported in the medical literature. In these individuals, the classic features of Klinefelter syndrome may be exaggerated, with low I.Q. or moderate to severe mental retardation also occurring.

In rare instances, an individual may possess both an additional X and an additional Y chromosome. The medical literature describes XXYY males as having slight to moderate mental retardation. They may sometimes be aggressive or even violent. Although they may have a rounded body type and decreased sex drive, experts disagree whether testosterone injections are appropriate for all of them.

One group of researchers reported that after receiving testosterone injections, an XXYY male stopped having violent sexual fantasies and ceased his assaults on teenaged girls. in contrast, Dr. Robinson found that testosterone injections seemed to make an XXYY boy he had been treating more aggressive.

Scientists admit, however, that because these cases are so rare, not much is known about them. Most of the XXYY males who have been studied were referred to treatment because they were violent and got into trouble with the law. It is not known whether XXYY males are inherently aggressive by nature, or whether only a few extreme individuals come to the attention of researchers precisely because they are aggressive.


The parents of XXY boys are sometimes concerned that their sons may grow up to be homosexual. This concern is unfounded, however, as there is no evidence that XXY males are any more inclined toward homosexuality than are other men.

In fact, the only significant sexual difference between XXY men and teenagers and other males their age is that the XXY males may have less interest in sex. However, regular injections of the male sex hormone testosterone can bring sex drive up to normal levels.

In some cases, testosterone injections lead to a false sense of security: After receiving the hormone for a time, XXY males may conclude they've derived as much benefit from it as possible and discontinue the injections. But when they do, their interest in sex almost invariably diminishes until they resume the injections.


The vast majority of XXY males do not produce enough sperm to allow them to become fathers. If these men and their wives wish to become parents, they should seek counseling from their family physician regarding adoption and infertility.

However, no XXY male should automatically assume he is infertile without further testing. In a very small number of cases, XXY males have been able to father children.

In addition, a few individuals who believe themselves to be XXY males may actually be XY/XXY mosaics. Along with having cells with the XXY chromosome count, these males may also have cells with the normal XY chromosome count. If the number of XY cells in the testes is great enough, the individual should be able to father children.

Karyotyping, the method traditionally used to identify an individual's chromosome count, may sometimes fail to identify XY/ XXY mosaics. For this reason, a karyotype should never be used to predict whether an individual will be infertile or not.

Health considerations

Compared with other males, XXY males have a slightly increased risk of autoimmune disorders. In this group of diseases, the immune system, for unknown reasons, attacks the body's organs or tissues. The most well known of these diseases are type I (insulin dependent) diabetes, autoimmune thyroiditis, and lupus erythematosus. Most of these conditions can be treated with medication.

XXY males with enlarged breasts have the same risk of breast cancer as do women-roughly 50 times the risk XY males have. For this reason, these XXY adolescents and men need to practice regular breast self examination. The free booklet Breast Exams: What You Should Know is available from the National Cancer Institute, listed in the Resources section. The last page of the booklet is a pullout chart listing the instructions for breast self examination. Although the booklet was written primarily for women, the breast self examination technique also can be used by XXY males. XXY males may also wish to consult their physicians about the need for more thorough breast examinations by medical professionals.

In addition, XXY males who do not receive testosterone injections may have an increased risk of developing osteoporosis in later life. In this condition, which usually afflicts women after the age of menopause, the bones lose calcium, becoming brittle and more likely to break.


Unfortunately, comparatively little is known about XXY adults. Studies in the United States have focused largely on XXY males identified in infancy from large random samples. Only a few of these individuals have reached adulthood; most are still in adolescence. At this time, researchers simply do not know what kind of adults they will become.

"Some of them have really struggled through adolescence," said Dr. Bruce Bender, the psychologist for the NICHD-sponsored study of XXY males. "But we don't know whether they'll have serious problems in adulthood, or, like many troubled teenagers, overcome their problems and lead productive lives."

Comparatively few studies of XXY males diagnosed in adulthood have been conducted. By and large, the men who took part in these studies were not selected at random but identified by a particular characteristic, such as height. For this reason, it is not known whether these individuals are truly representative of XXY men as a whole or represent a particular extreme.

One study found a group of XXY males diagnosed between the ages of 27 and 37 to have suffered a number of setbacks, in comparison to a similar group of XY males. The XXY men were more likely to have had histories of scholastic failure, depression and other psychological problems, and to lack energy and enthusiasm.

But by the time the XXY men had reached their forties, most had surmounted their problems. The majority said that their energy and activity levels had increased, that they were more productive on the job, and that their relationships with other people had improved. In fact, the only difference between the XY males and the XXY males was that the latter were less likely to have been married.

That these men eventually overcame their troubled pasts is encouraging for all XXY males and particularly encouraging for those diagnosed in childhood. Had they received counseling, support, and testosterone treatments beginning in childhood, these men might have avoided the difficulties of their twenties and thirties.

Although a supportive environment through childhood and adolescence appears to offer the greatest chance for a well-adjusted adulthood, it is not too late for XXY men diagnosed as adults to seek help.

Research has shown that testosterone injections, begun in adulthood, can be beneficial. Psychological counseling also offers the best hope of overcoming depression and other psychological problems. For referrals to endocrinologists qualified to administer testosterone or to mental health specialists, XXY men should consult their physicians.