The H Syndrome: A Genodermatosis

H syndrome (histiocytosis lymph adenopathy plus syndrome) is an autosomal recessive disorder caused by mutations in the SLC29A3 gene, encoding the human equilibrative nucleoside transporter (hENT3), characterized by cutaneous hyperpigmentation and hypertrichosis, hepatosplenomegaly, hearing loss, heart anomalies, hypogonadism, low height, hyperglycemia/insulin-dependent diabetes mellitus, and hallux valgus/flexion contractures. Exophthalmos, malabsorption, renal anomalies, flexion contractions of interphalangeal joints and hallux valgus, and lytic bone lesions, as well as osteosclerosis, are also seen. If these are lacking, the constellation of additional findings should raise suspicion for H syndrome. As most of the patients reported to date with H syndrome are from traditional, low-income populations, where consanguinity is common, it is highly important to develop a cheap and affordable technique for a mutation analysis. Two siblings presented to us, diagnosed as having insulin-dependent diabetes mellitus (IDDM) since the age of eight years and progressive flexion contracture of the small joints for seven-eight years. On examination, both had short stature. One also had bilateral cervical lymphadenopathy. The female had the Tanner stage of B3P3A2 M0 and the male had the Tanner stage of prepuberty. Laboratory workup, including antinuclear antibodies, rheumatoid factor, erythrocyte sedimentation rate, thyroid profile, and Celiac serology were negative. Genetic studies confirmed the diagnosis of H syndrome.