Three new 46,XX male patients: a clinical, cytogenetic and molecular analysis

Abstract

Background: XX males range phenotypically from completely masculinised individuals to true hermaphrodites and include a subset of SRY negative patients. The correlation between genotype (SRY+/-) and phenotype is still unclear.

Aim: To report three new patients with this rare condition, one of whom was diagnosed prenatally and another was SRY negative, and to verify in our patients whether the presence of SRY results in a more masculinised phenotype.

Patients and methods: We present two phenotypically normal XX male patients (10 and 13.5 years) and one 3.1 years old XX male with ambiguous external male genitalia Prader IV. The patients were diagnosed by clinical, hormonal, sonographic, genetic and histological criteria.

Results: Basal hormonal status was normal for phenotype but an excessive response to GnRH testing was noticed in the second patient together with insufficient hCG stimulation in all three patients. Pelvic ultrasound displayed male structures without Müllerian ducts; testicular biopsy, performed only in the intersex patient, showed Sertoli and Leydig cell hypoplasia. Chromosome analysis confirmed 46,XX karyotype. FISH analysis and molecular analysis by PCR were positive for Yp fragments/SRY gene on Xp in two patients and negative in the patient with ambiguous external genitalia.

Conclusions: In our observation Y chromosome-specific material containing the SRY gene translocated to the X chromosome results in a completely masculinised phenotype. In the intersex patient, incomplete masculinisation without SRY suggests a mutation of one or more downstream non-Y testis-determining genes.