46,Xinv(Yp+q-) in four generations of an Indian family.

Pericentric inversion of the human Y chromosome has been reported infrequently but it is known to be an inherited anomaly. Several individuals with such an inversion had concomitant karyotypic irregularities, amongst which trisomy 21, gonosome mosaicism, and the 47,XXY karyotype were common (Sparkes, Muller, and Veomett, 1970). This led to speculation that inversion of the Y chromosome signalled an increased tendency for non-dis-junction to occur in the progeny of 46,Xinv (Yp + q-) carriers. The discovery by Walzer, Breau, and Gerald (1969) of an inverted Y in 2 of 1332 phenotypically normal newborn males suggested that the inversion might be relatively common. The family reported here is descended from an immigrant pair who arrived in Durban during the 1880s from the Kathor province of India. The family was first identified when 3 of 4 sibs with congenital disorders were brought for investigation. It was found (Grace and Harris, 1970) that both sexes were affected; the parents were first cousins, and the affected boys and their normal father had a peri-centric inversion of the Y chromosome. The present study was done in an attempt to find the origin of the unusual Y chromosome. Family Study The family, whose pedigree is shown in Fig. 1, consisted of 74 living males and 39 living females. Of the males, only one (III.7) refused to cooperate and 15 were not available for examination. Peripheral blood and buccal mucosal scrapes were taken from 58 males. Metaphase karyotypes were prepared from cultured lymphocytes: in every instance the karyotype was 46,Xinv(Yp + q-). Representative partial karyotypes are shown in Fig. 2. Preparations of buccal mucosa, buffy coat, and metaphase chromosomes were stained with 0 25% quinacrine dihydrochloride (Sigma) for 20 minutes. The preparations were rinsed in tap water and mounted in buffer. Examination was done using a Zeiss microscope with ultraviolet illumination in conjunction with exciter filter BG 12 and barrier filters 53/44.