Jacob’s syndrome
Jacob’s Syndrome is a very rare chromosome syndrome. Male infants who are born with an extra Y male chromosome have Jacob’s syndrome. Normal males are born with an X and a Y chromosome. The extra Y chromosome is in inherited from the father. Jacob’s syndrome affects less than 200,000 people in the United States and occurs in only 1 out of every 1,000 births. Only 5 male infants a day are born with it. Other names for Jacob’s syndrome are XYY Karyotype, XYY syndrome and YY syndrome. Males who are born with this syndrome do not have any unusual features and the only way the syndrome is discovered is through genetic testing. Most boys born with the extra Y chromosome have a normal sex development and no problems with fertility when they mature.
The most prevalent symptoms associated with Jacob’s syndrome are delayed emotional development and learning problems in school. Up to 50% of all boys with this syndrome will be slower in speech development and language skills as compared to only about 10% of boys born without the extra Y chromosome. The first incidence of this syndrome was reported in 1961 after a man was karyotyped who had a daughter with Down Syndrome.The cause of this genetic error is a random formation of sperm cells which causes the extra copy of the Y chromosome to be passed on to the embryo. Males who have this syndrome may have higher than normal levels of testosterone.
The discovery of this syndrome spurred a controversy in 1965 that was led by a geneticist who published findings that a large number of men in prison were found to have the extra Y chromosome. This gave rise to a theory that men who had Jacob’s syndrome were more prone to criminal behavior and that they are more aggressive and had violent tendencies. However these conclusions were later proven to be false. There is no proven link that connects aggressive behavior and Jacob’s syndrome. During the 1970’s such reports led to women having abortions if they knew the fetus had this extra Y chromosome via genetic testing. The false belief that males born with Jacob’s syndrome are more violent and aggressive was proven to be a myth in 1974 by a prominent geneticists by the name of Jon Beckwith. Bechwith successfully argued that thinking that males born with this syndrome were anti social and prone to criminal behavior was only based on medical folklore and not scientific fact. However, many researchers rejected the his findings and set about to create studies to support the idea that XYY males tended to be more aggressive. These studies have been proven to be flawed for various reasons. Some scientists believe that more research needs to be done in this area however there has to be a better control group used instead of only men in prison or mental institution being used for test subjects.
Some other common symptoms associated with Jacob’s syndrome are immaturity, swollen joints, arthritis, joint stiffness, impaired joint mobility and camptodactyly and chest pain. Boys with this syndrome are usually very tall. Parents who have a child born with Jacob’s syndrome should be given all the information they need about it. However, most boys who have the extra Y chromosome will go through life without having been diagnosed. Most males who have Jacob’s syndrome do not exhibit any abnormal behavior or physical characteristics. There is no treatment needed for this syndrome. The only way to discover Jacob’s syndrome is through genetic testing. If you have any concerns about this Syndrome you can discuss them with a qualified medical doctor.
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