The first Hermansky–Pudlak syndrome type 9 patient with two novel variants in Chinese population

Hermansky‐Pudlak syndrome 9 (HPS‐9) is a recessive disorder caused by BLOC1S6 gene. There are only four variants identified from four HPS‐9 patients so far. Here, we reported the first HPS‐9 patient in a Chinese population. He had brownish‐yellow hair, white skin, brown irises with visual acuity, photophobia and nystagmus. Two novel variants, c.148G>T (p.Glu50*) and c.351dupT (p.Ile118Tyrfs*10) in BLOC1S6 gene were identified by whole‐exome sequencing (WES). Absence of platelet dense granules was found by whole‐mount platelet electron microscopy and Western blotting assays showed the destabilized BLOC‐1 subunits. He had recurrent bruising and was found to have abnormal brain waves by electroencephalogram, but did not develop thrombopenia, immunodeficiency or other symptoms reported in other HPS‐9 patients. This is the first case report of BLOC‐1 mutation in a Chinese population and our findings expand the mutational spectrum of HPS genes.