Heimler syndrome (HS) is a rare recessive disorder characterized by sensorineural hearing loss (SNHL), amelogenesis imperfecta, nail abnormalities, and occasional or late-onset retinal pigmentation. It is the mildest form known to date of peroxisome biogenesis disorder caused by hypomorphic mutations of PEX1 and PEX6 genes. We report on a second Moroccan family with Heimler syndrome with early onset, severe visual impairment and important phenotypic overlap with Usher syndrome. The patient carried a novel homozygous missense variant c.3140T > C (p.Leu1047Pro) of PEX1 gene. As standard biochemical screening of blood for evidence of a peroxisomal disorder did not provide a diagnosis in the individuals with HS, patients with SNHL and retinal pigmentation should have mutation analysis of PEX1 and PEX6 genes.
Keywords: Heimler syndrome; Moroccan; PEX1; Retinitis pigmentosa; Variant.
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