An Egyptian family with H syndrome due to a novel mutation in SLC29A3 illustrating overlapping features with pigmented hypertrichotic dermatosis with insulin‐dependent diabetes and Faisalabad histiocytosis

The SLC29A3 gene, encoding hENT3, a member of the equilibrative nucleoside transporter family, has recently been found mutated in Faisalabad histiocytosis, pigmented hypertrichotic dermatosis with insulin‐dependent diabetes, familial sinus histiocytosis with massive lymphadenopathy (SHML), and H syndromes. We here report clinical and genetic findings of an Egyptian family with H syndrome. We describe two siblings, a 19‐yr old girl and a 15‐yr old boy, of consanguineous parents. From 5 yr of age, the girl developed bilateral flexion deformity of interphalengeal joints and insulin‐dependent diabetes mellitus. At age 7 yr, prominent hyperpigmented patches appeared on the skin at lower limbs, genitalia, and trunk. On clinical examination, she had hepatosplenomegaly, generalized lymphadenopathy, left ventricular hypertrophy, sensorineural hearing loss, hypogonadism, short stature, and characteristic dysmorphic features. Her brother had fixed flexion contractures of the feet, profound sensorineural hearing loss, characteristic dysmorphic features, but no diabetes. DNA sequence analysis revealed a homozygous mutation (c.300+1G>C) in SLC29A3 in both siblings. The phenotype and genotype of the siblings were compatible with that of the H syndrome, although the features were overlapping with those found in pigmented hypertrichotic dermatosis with insulin‐dependent diabetes, familial SHML, and Faisalabad histiocytosis, indicating that these four syndromes may be regarded as one disease with varying phenotypic features. A new, common name for these conditions is warranted.