48, XXXY Syndrome
XXXY syndrome is a chromosome condition that only affects males. An estimated 1 in 17,000 to 50,000 boys is born with 48,XXXY. XXXY syndrome can also be called 48,XXXYsyndrome, because instead of 46 chromosomes, there are 48 (22 pairs, ie 44 chromosomes, plus the four sex chromosomes in XXXY). Most males with 48,XXXY have three X chromosomes in all the cells of their body. Babies with 48,XXXY achieve their developmental milestones later than typically developing babies. They have gross motor delay because they usually have low muscle tone and difficulties with coordination. Both rolling and sitting are
delayed although there is some evidence that babies sit earlier and with greater confidence than they move. Moving by shuffling or crawling between 11 and 18 months and walking between 17 months and two years two months. Bendy (hyperextensible) joints and flat feet are common.
The parents of a son with 48,XXXY almost always have normal chromosomes in their body’s cells, so they are not routinely tested. Why the two extra X chromosomes were incorporated is not well understood but it is known that they can come from either the mother or the father but not so far as is known from both parents. What is known is that the syndrome arose before conception (when a baby is made) and there is nothing that the parents did before or during pregnancy to make it happen. No environmental, dietary or lifestyle factors are known to cause it. It is no-one’s fault.
Is 48, XXXY a variant of Klinefelter Syndrome?
Individuals with 48,XXXY have their own unique physical and behavioural characteristics and should not be considered a variant of Klinefelter syndrome. Males with Klinefelter syndrome have a single extra X chromosome, so their make-up is 47,XXY. During puberty their testosterone production is decreased and while having normal sexual function, they generally do not father children of their own. The penis in boys with 48,XXXY is often small at birth. It is likely to remain small but may grow to within the normal range. The term “micropenis” is often used.
As a result of early language deficits, they have increased propensity for reading and spelling problems and social difficulties. Their overall IQ may be below their age-matched typical peers, and they are likely to have a lower verbal IQ due to language delay. The additional X chromosome in 48,XXXY has more influence on physical, cognitive and behavioural features than in 47,XXY. For instance, males with 48,XXXY may have delays in motor skills, language and social development. So early and ongoing intervention and educational planning are critical in ensuring that boys continue to progress in their developmental skills.
delayed although there is some evidence that babies sit earlier and with greater confidence than they move. Moving by shuffling or crawling between 11 and 18 months and walking between 17 months and two years two months. Bendy (hyperextensible) joints and flat feet are common.
The parents of a son with 48,XXXY almost always have normal chromosomes in their body’s cells, so they are not routinely tested. Why the two extra X chromosomes were incorporated is not well understood but it is known that they can come from either the mother or the father but not so far as is known from both parents. What is known is that the syndrome arose before conception (when a baby is made) and there is nothing that the parents did before or during pregnancy to make it happen. No environmental, dietary or lifestyle factors are known to cause it. It is no-one’s fault.
Is 48, XXXY a variant of Klinefelter Syndrome?
Individuals with 48,XXXY have their own unique physical and behavioural characteristics and should not be considered a variant of Klinefelter syndrome. Males with Klinefelter syndrome have a single extra X chromosome, so their make-up is 47,XXY. During puberty their testosterone production is decreased and while having normal sexual function, they generally do not father children of their own. The penis in boys with 48,XXXY is often small at birth. It is likely to remain small but may grow to within the normal range. The term “micropenis” is often used.
As a result of early language deficits, they have increased propensity for reading and spelling problems and social difficulties. Their overall IQ may be below their age-matched typical peers, and they are likely to have a lower verbal IQ due to language delay. The additional X chromosome in 48,XXXY has more influence on physical, cognitive and behavioural features than in 47,XXY. For instance, males with 48,XXXY may have delays in motor skills, language and social development. So early and ongoing intervention and educational planning are critical in ensuring that boys continue to progress in their developmental skills.
