Clinical, Histochemical, and Molecular Study of Three Turkish Siblings Diagnosed with H Syndrome, and Literature Review.

BACKGROUND: The term "H syndrome" was coined to denote the major clinical findings, which include hyperpigmentation, hypertrichosis, hearing loss, hepatosplenomegaly, hyperglycaemia, hypogonadism, hallux flexion contractures, and short height.

OBJECTIVE: To report the clinical, endocrinological, histochemical, and genetic findings of three siblings.

METHODS: Skin and liver biopsies were taken to investigate the histochemical characteristics of hyperpigmented hypertrichotic skin lesions and massive hepatomegaly. The levels of basal serum thyroid hormones, oestradiol, total testosterone, follicle-stimulating hormone, luteinising hormone, and stimulated growth hormone (GH) were measured to investigate the endocrine aspects of the syndrome. Mutation analysis was carried out in all six exons and exon-intron boundaries of SLC29A3 by direct sequencing.

RESULTS: Physical examination of the patients revealed common charac-teristic findings of H syndrome. Additional clinical findings were sectorial iris atrophy in the younger sister. Laboratory evaluation revealed microcytic anaemia, markedly increased erythrocyte sedimentation rate and C-reactive protein levels, and humoral immune deficiency in the younger siblings, who presented with recurrent fever and sinopulmonary infection. Two different GH stimulation tests revealed GH deficiency in the younger sister with short stature. Liver and skin biopsies revealed polyclonal lymphohistiocytic and plasma cell infiltration. Sequencing of SLC29A3 in the three siblings revealed a novel homozygous mutation in exon 6, which caused the transition of arginine to tryptophan.

CONCLUSION: This study not only extended the clinical and mutation spectrum of SLC29A3 in H syndrome, but also showed that short children should be assessed according to the guidelines for short stature in children.