Objective: The De La Chapelle syndrome (XX male) is a peripheral hypogonadism concerning males with 46,XX karyotype. We conducted a retrospective study of 18 cases and report the main clinical biological and hormonal characteristics.
Patients and methods: Clinical features (weight, height, aspect of the external genital organs, body hair, gynecomastia), hormone levels (testosterone, gonadotrophin, baseline and stimulated prolactin estradiol), and results of a Barr test and karyotype were recorded in all patients in addition to search for the SRY gene (in 8 of the 18 patients). Findings were compared with a matched male population and a Klinefelter syndrome population.
Results: Microrchidia was found in almost all the patients while the penis had a normal size. Signs of hypoandrogenism were frequent and gynecomastia was present in half the cases. De La Chapelle patients differed from Klinefelter patients by the absence of dysmorphism.
Discussion: Patients with De La Chapelle syndrome diagnosed around the age of 20 years do not have borderline disorders associating genitalia anomalies or sexual ambiguity. The majority of the patients bear the testis determining SRY gene on one of the X chromosomes, providing the rational explanation of the male phenotype, but 20% of the XX males doe not have this gene. The role of certain key genes that could be implicated in abnormal sexual differentiation is known, but the complexity and heterogeneous nature of this syndrome leaves many questions unanswered. Therapy is based on androgen replacement therapy given at an early stage.