XXXXY, 49 syndrome
1 in 85,000 to 100,000 male births are to a baby with a karyotype of XXXXY, 49. To put this into perspective, this is like having TWO sets of conjoined twins!!! Wow, 49er's are hard to come by.
Sometimes it is refered to as a "variant" of klinefelters syndrome (XXY, 47) because it doesn't actually have a name of its own. This is a bit of a misnomer however, because 49ers have their own characteristics that are unique to 49ers. Thus, as mentioned in a medical journal article, XXXXY 49 has its own phenotype, and genotype, and is not Klinefelters.
Although 49 Syndrome is genetic, it is not believed to be hereditary, meaning that the chances that another child with 49, XXXXY Syndrome, OR ANY OTHER chromosomal abnormality, in the same family are relatively small and are around 1%. (barring any additional percentages based on the age of the mother etc.)
In a typical male fetus there is a testosterone surge inutero. 49er's miss that surge. Shortly after birth, typical male babies have another testosterone surge, which is nearly equivalent to an adult man's. 49ers, again, miss this neonatal surge. Getting testosterone replacement therapy in this neonatal timeframe can help minimize the effects of the micro penis because of the hypogonadism. Testosterone also is being found to help with muscle control for the hypotonia which 49ers tend to have. As well as increasing their activity levels, and language abilities. In the near future, a study will be done using Oxandrolone - a weak male steroid that is used in children with Turner's sydrome for growth. It is a weaker male steroid, and more easily metabolized in the liver than testosterone.
Other features may include cleft palate, club feet, severely impaired speech, respiratory conditions, behavioral problems, short or broad neck, low birth weight, hyperextensible joints, short stature, narrow sholders, round face in infancy,(Look very much like a cherub) coarse features in older age, hypertelorism, epicanthal folds, prognathism, gynecomastia (rare), congenital heart defects (PDA is most common), skeletal anomalies: genu valgus, pes cavus, fifth finger clinodactyly, muscular hypotonia, hypoplastic genitalia, cryptorchidism, pea-size testes, micropenis, and infantile secondary sex characteristics.(and sterility in adulthood). Renal problems, hypothyroidism. Radioulnar synostosis(arm unable to make the movement to turn a doorknob for example), mental deficiency to varying degrees, hypogonadism, and white brain matter abnormalities, which possibly can be effectively treated with Aricept, a drug used in Alzheimers patients, and now has been found affective in Trisomy 21 (Down Syndrome). All of this is very mild compared to other rare chromosomal abnormalities, and of course, each child is unique, and may show many of these symptoms, or very few of them.
Mentally, 49, XXXXY Syndrome males have varying degrees. Many people compare it mentally to Down Syndrome, in that it varies greatly from person to person. Major milestones like sitting and walking are reached, but may take a bit longer because of muscle tone issues, along with motor planning challenges. The key to discovering just how intelligent a 49er is, is by creating a new method of IQ testing which doesn't rely so heavily on language skills, since this is where the 49er has the most difficult challenges. We parents believe our son's are much more intelligent than ever previously thought.
If 49, XXXXY Syndrome is present in a newly diagnosed patient, the best way to learn and to get insight is to read about real people living with it. Contact other families and hear real life experiences. These are the people that will be able to provide you with an abundance of actual information, and of course, much needed hope.
49,XXXXY karyotype shows a unique phenotype syndrome. Individuals with this syndrome are male. However, a female variant XXXXX 49 also exists. They exhibit characteristic's mentioned above. Aneuploidy above one extra chromosome is usually fatal, but because of X-inactivation, which "turns off" all but one X chromosome per cell(in males, 2 in females), the effects of 3 extra chromosomes are reduced. Currently, it is unknown how the turning off process happens, and it is possible, some are turned off, while others remain activated. More information about the female 49ers can be found under Turner syndrome.
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