Double aneuploidy: down syndrome associated with klinefelter syndrome

ABSTRACT

The occurrence of double aneuploidy, i.e., the existence of two meiotic non-disjunction events is relatively rare. Although the association between double autosomal trisomy, such as trisomy 21 and 18 is extremely unusual, rare cases of combination between Down syndrome and gonosomal trisomy have been reported. We report the case of an Indian boy with Down and Klinefelter syndrome. The patient's condition resulted from de novo trisomy-21 with extra X-chromosome [48, XXY, +21]. He was born normally with birth weight, length and head circumference of 2590 gram, 45 cm and 31 cm respectively. The age of the mother was 31 years and father was 32 years at the time of delivery. He had dysmorphic features of Down syndrome with an imperforated anus, severe mental retardation, small phallus and bilateral undescended testicles but no congenital heart disease. The weight and height were on the 3rd centile while the head circumference was below the third centile. The patient developed hypothyroidism by the age of six years and was maintained on L-thyroxin. Testosterone level was pre-pubertal and failed to rise after human chorionic gonadotropin [HCG] stimulation test