Trisomy 21 with XYY

Abstract

A case of double aneuploidy involving chromosome 21 and Y is reported in an eight-month-old infant with developmental delay and failure to thrive. Patient had all classical phenotypical features of trisomy 21 except, absence of epicanthal folds. The diagnosis was confirmed by cytogenetic study performed on peripheral blood leucocyte culture using G-banding. Literature review revealed only 17 cases of XYY and trisomy 21 reported so far. No such case is reported in Indian literature. Relevant literature is reviewed and possible effects of trisomy 21 on XYY and that of XYY on trisomy 21 has been discussed. A routine chromosomal study even in patient with classical features of Down syndrome has been advocated. Interestingly, our patient also had left to right shunts at atrial and ductal level and tricuspid regurgitation. Given the rarity of the disorder and scanty published data the incidence, phenotype and recurrence risk are difficult to establish.

Double Aneuploidy: A Case of Trisomy 21 with XYY

“…In patients with double aneuplodies phenotype is more commonly determined by autosomal aneuplodies. Compatible with the literature; the clinical phenotype of Down syndrome in our patient was dominant as expected (7)(8)(9). Classical trisomy 21 results from maternal meiotic nondisjunction.…”

“…Our patient (this case) had ASD, VSD and pulmonary hypertension. Parmar et al also reported similar congenital heart disease in previous case (7). Polycythemia may be present in autosomal aneuploidies.…”

“…Classical trisomy 21 results from maternal meiotic nondisjunction. Y chromosome of XYY is always paternal and it occurs by nondisjunction at meiosis II or mitosis after fertilization (3,7,9). Etiological predisposition factor is not known for 48,XYY,+21.…”

Double Aneuploidy - A Rare Condition : Report of Two Cases

“…Compatible with the litera-ture; the clinical phenotype of Trisomy 21 in our patients was dominant as expected . 11,12,13 In our first case the phenotypic features of XYY were not present. An XYY sex chromosome complement, without any abnormal phenotypical effect, may be found in the general population.…”

“…Behavioral prob-lems like hyperactivity and anger onset may be promi-nent at childhood or adolescence which may be found at a later age. 11 In patients with Klinefelter syndrome, the diagnosis is often made later in life, and they have a tall stature, absent or decreased facial and pubic hair, small hyalinized testes, a small penis, and feminine distribution of adipose tissue, including gynecomastia . 15 Signs that are sometimes noted in infants with Klinefelter syndrome are an underdeveloped phallus and scrotum, valviform hypospadia, hyperpigmentation of scrotal raphe, and small or ectopic testis .…”