Mongoloid twins with 48 chromosomes (AA + A₂₁XXY)

Abstract

Summary A 7‐month‐old pair of mongoloid twins is described (one of which died) who both had 48 chromosomes with A A + A 21 XXY. The pair must have been an identical twin, who would develop Klinefelter's syndrome. L. E. Nijenhuis (Anthropogenetics Dept. Red Cross Blood Transfusion Laboratory, Amsterdam) informed us on the data of blood groups. We are indebted to E. D. A. M. Schretlen, paediatrician (Paediatric Clinics, R.C. University) for performing tibia puncture. Our thanks are due to W. G. van Aken (med. student), Miss M. A. W. Janssen and A. P. Jansen for valuable assistance in counting, analysing and technical help. Dr J. C. Seelen, M.D. (Gynaecological Clinics, R.C. University) gave valuable help in evaluating the preparations for Barr‐bodies.