XYY Boys


I have a 5 year old son that has Cerebral Palsy, XYY syndrome, Obsessive-Compulsive Disorder (OCD), mitral valve regurgitation, and asthma. We have been told that none of these are connected. Actually, until he was 3 1/2 we were told there was nothing wrong with him! But he is always having some sort of problem -- next week we are taking him to an orthopedist because he is shoulder stooping. I am looking for something - anything. His teacher in school has a problem with him, and it is related to the fact that he is disabled -- he is not like the other children (cutting, pasting, handwriting etc.). They want to put him in special ed, but he is smart! Can't these problems be related to each other - it seems so odd that I have 3 healthy children and one that has 5 completely unrelated problems! He can walk, but not run very well. He can talk, but you have to listen closely sometimes. He is friendly, but frustration does exist when there is a lack of patience. I know you probably don't have a lot of time for all of this, I know that the many doctors we have seen have not had time to really deal with this, however, any information you might be able to send me would be greatly appreciated.
Mary Roseberry - Mother - Paola, Kansas

Dr. Greene's Answer

My hat is off to you, Mary. Your instinct is leading you to an often unrecognized root of many problems in very active boys. Mothering four children is a huge task — all the more so when one of them has behavior problems, heart problems, and asthma. Your instinct that your son’s five problems (six, if you count the shoulder stoop) are related is right on target. I’m glad that you have pursued this, even though others have told you that his problems are not connected.

Difficult boys often have an undiagnosed, unsuspected genetic mutation that lies at the root of their behavioral or physical problems. Most boys inherit one sex chromosome from each parent: an X chromosome from their mothers and a Y chromosome from their fathers. They are called XY. (Most girls are XX, having received an X chromosome from each of their parents.) Your five-year-old son wound up with 2 Y chromosomes — an extra helping of maleness – called XYY Syndrome or XYY Karyotype.

XYY is a fairly common condition. By mid-childhood, these boys tend to be big, aggressive, and active. Most of the time their XYY condition is undetected throughout childhood and even adulthood. These children need understanding parents, doctors, and teachers.

Unfortunately, much of the older medical literature on XYY syndrome is misleading. Many articles suggest that XYY syndrome is characterized by mental retardation. I disagree. Chromosome studies are usually done in mentally retarded children to look for an underlying cause. Many of them turned out to be XYY, leading to the conclusion that XYY children are often mentally dull. About 1 in 1,974 boys referred for chromosome studies are XYY (Genetic Counseling, 1995).

Chromosome studies are usually NOT done in otherwise healthy boys. One study showed that the majority of boys with XYY “do not look or behave in a manner which prompts testing for a chromosome abnormality” (Prenatal Diagnosis, 17:4: 363–368, 1997). In Denmark, in 1990, researchers tested the chromosomes of 34,910 newborns to see what they would find in a typical population.

About 1 in every 851 male newborns is an XYY boy (Birth Defects, 1990).

Some children with XYY are developmentally delayed, but XYY is less common among the delayed population than in the general population. Children with XYY can have low, normal, or above normal intelligence. The extra helping of maleness does seem to have some effect on intelligence, though. These boys tend to score about 10 to 15 points lower than their siblings on standardized IQ tests.

Most XYY boys tend to be tall (by mid-childhood), with large teeth, long ears, a long face, and long hands and feet. Some have a mildly sunken breastbone. Some have a prominent nasal bridge. Even if a child has all of these attributes, the features are usually so subtle that the condition is never diagnosed. And none of these physical attributes is absolute. Children and adults with known XYY are sometimes average height, or even short, with small hands and feet. Different boys express the extra Y chromosome differently.

Typical findings in XYY syndrome include things you might suspect from an extra helping of maleness. Girls tend to develop faster than boys. XYY boys tend to be clumsier (especially in fine motor skills like cutting, pasting, and handwriting), develop more slowly, and often have delayed puberty. XYY boys often have severe acne.

The biggest problems usually have to do with personality and behavior. Girls are sometimes more sensitive and nurturing than boys. XYY boys are often (but by no means always) more aggressive and less tuned in to the feelings of others than their counterparts. The Denmark general population study found “no increased frequency of mental disorders,…behavior disorders,… or criminal activity” in the XYY boys among the 34,910 newborns studied — but this was only 20 XYY boys.

Another sobering study found that the frequency of XYY among institutionalized male juvenile delinquents was 1 in 35! (Smith’s Recognizable Patterns of Human Malformation). Taken together, these studies indicate that an individual boy with XYY syndrome will probably not have serious mental, behavioral, or criminal problems — but that his odds are 24 times more likely than those for an XY boy.

Mary, your son may not have cerebral palsy. Cerebral palsy is a stable, non-progressive motor disorder, appearing before age 3, caused by non-continuing damage to the brain, and not attributable to another cause (Dorland’s Medical Dictionary). You state that your son’s problems didn’t begin until he was three and a half. Moreover, motor abnormalities are a known part of XYY syndrome (Rinsho Shinkeigaku, 1992 — this is a Japanese journal. Most of the literature on XYY comes from Japan, Russia, Germany, or Denmark — not the United States). Fine motor difficulties are particularly common among XYY boys.

The other concerns you mentioned, Mary, could all be connected to the XYY syndrome. His obsessive-compulsive disorder is probably an expression of his extra Y chromosome. XYY syndrome has also been associated with a variety of heart defects (including valvular regurgitation) which seem to result from an elongated heart (Japanese Journal of Medicine, Feb. 27, 1988).

I have found no direct link in the medical literature between asthma and XYY, but I believe that they may be connected. Asthma is caused by sensitization to environmental triggers (such as cigarette smoke, airborne allergens, chemicals, or viruses) in a genetically predisposed individual. That genetics plays a major role in asthma is without question, but the mechanism of inheritance appears to be complex. We do know that boys are up to twice as likely as girls to develop asthma. It would make sense that a boy with a double helping of maleness could have an even greater chance than his peers. Again, I have found no such statements in the medical literature, but I expect that time will prove that many of the conditions that are more common in boys than girls will be even more common in XYY boys.

Your big challenge is to understand the implications of your son’s extra Y chromosome, and to help him turn this into a strength. Help him find ways to channel his unique personality in constructive ways. Karate (taught by an instructor who emphasizes discipline and control, rather than aggression) might be a great outlet. Swimming might be another one. Help him to find physical activities at which he can excel. Also help him grow in his areas of potential (and real) weakness. Teach him to nurture by giving him opportunities to care for plants or pets. Help him to learn to recognize what others are feeling by asking him what he thinks others are feeling. This can work particularly well with siblings — especially during times of conflict.

I am very interested in tracking the development of XYY boys. Please keep me posted on your son (and anyone else you find with XYY) in the Comments section below. There is so little medical data available that, currently, even doctors do not agree on the possible effects of having an extra Y chromosome. I believe, in the next 20 years, we will find new insights into the conditions associated with XYY boys that will change the way they are viewed by society, and the way they are treated by medical professionals.

Last medical review on: July 11, 2010
About the Author
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Dr. Greene is a practicing physician, author, national and international TEDx speaker, and global health advocate. He is a graduate of Princeton University and University of California San Francisco.
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