Not to be confused with XXYY Syndrome, XXXYY Syndrome, XXXYY Syndrome.
49,XXYYY syndrome is a intersex variation in which a CTM has two extra Y chromosomes and one extra X chromosome. It is a very rare variation amongst DMAB individuals, and it has no estimated rarity.
Those with this variation tend to have facial dysmorphism, mild microcephaly, limitation of supination at the elbows, delayed bone age, and moderate intellectual disability (such as autism.)[1] This variation is often considered a subset or a related variation to kilnefelter syndrome.
Medical proffesionals looked into tissues sampled for chromosome studies of external ambiguous genitalia and abdominal gonads, consisting of a left ovotestis and a right primitive testis, and found that they contained cells 46,XX, 47,XXY and 49,XXYYY sex chromosomes.[2]
History
This variation appears to have been discovered in 1967 or earlier,
Resources
https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1440-1754.1967.tb01693.x