CHARACTERIZATION OF AN ISODICENTRIC Y-CHROMOSOME FOR THE LONG ARM IN A NEWBORN WITH MIXED GONADAL-DYSGENESIS

A newborn infant was referred for evaluation because of ambiguous geni talia. Examination of the genitalia revealed a hypospadiac phallus mea suring 1.5 cm in length with chordee, Subtle phenotypic features consi stent with Turner syndrome were present including hypertelorism, anti- mongoloid slant to the eyes, mild widening of the neck, but no definit ive webbing, shield like chest and positive cubitus valgus. A pelvic a nd renal sonogram confirmed the presence of a uterus and normal-appear ing kidneys. There: was incomplete fusion of the scrotum. No gonads we re palpable vyithin the scrotal sac, The patient tvas assigned a femal e gender on the basis of the presence of a uterus, the phenotypic appe arance of the genitalia and the malignant potential of the gonads, The cytogenetic findings with QFQ-banding revealed an abnormal karyotype, i.e., mos 46,X,idic(Y) (p11.2)[77]/45,X[29]/46,X,idic(Y) ]/47,X,idic( Y)(p11.2),+idic(Y)(p11.2)[1]/46,XY[1]. The presence of an abnormal iso dicentric Y-chromosome was evaluated by FISK-technique to ensure a fin er characterization than routine methods. The genotype-phenotype corre lation could not be established since mosaicisms of highly variable na ture can exhibit an unpredictable outcome.