XYYY syndrome
chromosomal disorder
XYYY syndrome, also known as 48,XYYY, is a chromosomal disorder in which a male has two extra copies of the Y chromosome. The syndrome is exceptionally rare, with only twelve recorded cases. The presentation of the syndrome is heterogeneous, but appears to be more severe than its counterpart XYY syndrome. Common traits include borderline to mild intellectual disability, infertility, radioulnar synostosis (the fusion of the long bones in the forearm), and in some cases tall stature.
Presentation
The presentation of XYYY syndrome is variable and at this time not entirely clear. As all known cases were diagnosed postnatally (after birth), and the similar XYY syndrome is known to have a milder phenotype in prenatally than postnatally diagnosed cases, it is suspected that many cases of XYYY syndrome may be mild or asymptomatic.
The intellectual abilities of known XYYY cases have varied, especially in cases with mosaicism, but in most cases are in the borderline intellectual functioning range (IQ between 70–85). Performance IQ is often higher than verbal IQ. Mild speech delays have been reported. Basic self-care skills, such as toileting, dressing, eating, and hygiene, are normal or at most slightly delayed. A number of minor skeletal anomalies are observed, such as clinodactyly, radioulnar synostosis (the fusion of the long bones in the forearm), and poor dental development.
“XYYY syndrome” enters the record as chromosomal disorder. Crown Archives preserves that source wording while asking what XYYY, syndrome and chromosomal can confirm, complicate or overturn.
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This entry incorporates text from “XYYY syndrome” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.