A patient with TPCN2-related hypopigmentation and ocular phenotype.

Abstract

Pigmentation is orchestrated by hundreds of genes involved in cellular functions going from early developmental fate of pigment cells to melanin synthesis. The Two Pore Channel 2 (TPC2) a Ca2+ and Na+ channel acidifies melanosomal pH and thus inhibits pigmentation. A young patient was recently reported with generalized hypopigmentation but uneventful ocular examination, caused by the de novo heterozygous TPCN2 variant c.628C>T;p.Arg210Cys that constitutively activates TPC2. Here we report a young patient with the same de novo variant presenting with generalized hypopigmentation, and ophthalmologic features including low grade retinal hypopigmentation and foveal hypoplasia, photophobia, mild hypermetropia, and astigmatism, which are features of albinism. Skin fragility and episodes of fever with diarrhea and fatigue were also observed. This extends the phenotype of patients with TPCN2 variants, warranting further investigations in patients with alterations of this gene, and raises the question whether TPCN2 might be considered as an albinism gene.