[H syndrome: First reported paediatric case in Latin America]

H Syndrome is an extremely rare genetic disease, with a multisystemic character and which can be identified in early childhood, offering the opportunity of specific treatment and genetic counselling.

To present a clinical case with "typical" characteristics of H Syndrome.

The case is presented of an 8-year-old male patient who presented with testicular tumours and skin lesions characterised by hyperpigmentation with hypertrichosis, language delay, short stature, and joint deformities. He also presented with bilateral sensorineural hearing loss, anaemia, hypergammaglobulinaemia, and bone disorders. Histopathology studies of the skin and testicular masses reported lymphoplasmacytic infiltration. Sequencing analysis of gene SLC29A3 showed the homozygote mutation c.1087 C>T (p.Arg363Trp; rs387907067).

These findings are consistent with H syndrome, and this is the first reported case in Latin America. The key to the diagnosis is the finding of hyperpigmentation with hypertrichosis.