Mutation in the SLC29A3 Gene in an Egyptian Patient with H Syndrome: A Case Report and Review of Literature.

Histiocytosis-lymphadenopathy plus syndrome (H syndrome) is caused by mutations in the SLC29A3 gene that result in histiocytic infiltration of numerous organs. Patients suffering from this disorder can be easily mistaken for similar conditions such as Muckle-Wells syndrome. We present a 9.5-year-old boy, who is the offspring of a consanguineous marriage. He suffered from sensorineural hearing loss, dark hyperpigmented indurated dry areas on the medial thighs sparing the knees with hypertrichosis on the affected areas, and areas of hypopigmentation on the abdomen. The patient displayed mild dysmorphism including frontal bossing, synophrys, bilateral proptosis (with normal thyroid function), thick eyebrows, flat nose, long philtrum, and pectus excavatum. Formal intelligence testing showed that he was a slow learner. Laboratory findings included elevated serum amyloid-A, erythrocyte sedimentation rate, and total proteins in urine tests. Complete blood count showed mild microcytic hypochromic anemia. The molecular analysis was crucial to confirm the provisional clinical diagnosis. H syndrome is a rare autoinflammatory syndrome with pleiotropic manifestations that affect many organs and can be mistaken for other conditions. Our patient's description may expand the phenotype of H syndrome, as areas of hypopigmentation were observed on the abdomen. Molecular analysis of SLC29A3 -related diseases is essential to highlight the variability and increase the awareness of H syndrome aiming for early diagnosis and proper treatment.