h syndrome h syndrome h syndrome, also known as histiocytosis-lymphadenopathy plus syndrome or phid, is a rare genetic condition caused by mutations in the slc29a3 gene which encode the human equilibrative nucleoside transporter (hent3) protein. h syndromeother nameshistiocytosis-lymphadenopathy plus syndromethis condition is inherited in an autosomal recessive manner it is also known as faisalabad histiocytosis, familial rosai-dorfman disease, sinus histiocytosis with massive lymphadenopathy and pigmented hypertrichosis with insulin-dependent diabetes mellitus syndrome. presentation this syndrome has a number of different clinical features many of which start with the letter 'h' giving rise to the name of the syndrome. these features include hyperpigmentation hypertrichosis hepatosplenomegaly hearing loss heart anomalies hypogonadism low height (short stature) hyperglycemia/diabetes mellitus hallux valgus/flexion contractures exophthalmos, malabsorption and renal anomalies have also been reported. genetics the slc29a3 gene is located on the long arm of chromosome 10 (10q22).the causative gene was identified in 2010. pathogenesis this is not understood at present. management there is no curative treatment for this condition at present. management is directed to the clinical features. history this condition was first described in 1998.