The XXXY Klinefelter Syndrome in Childhood

The XXXY variety of Klinefelter syndrome should be suspected when the following features are observed in a mentally retarded boy: decreased upper-lower body segment ratio, microcephaly, clinodactyly with brachymesophalangia of the fifth fingers, and dermatoglyphic arches on nine or ten fingers associated with attriradius in t 1 position. These features are not puberty-dependent like the endocrine characteristics of Klinefelter syndrome and, therefore, permit an early diagnosis.