Broadening the ocular phenotypic spectrum of ultra-rare BRPF1 variants: report of two cases.

INTRODUCTION: BRPF1 gene on 3p26-p25 encodes a protein involved in epigenetic regulation, through interaction with histone H3 lysine acetyltransferases KAT6A and KAT6B of the MYST family. Heterozygous pathogenic variants in BRPF1 gene are associated with Intellectual Developmental Disorder with Dysmorphic Facies and Ptosis (IDDDFP), characterized by global developmental delay, intellectual disability, language delay, and dysmorphic facial features. The reported ocular involvement includes strabismus, amblyopia, and refraction errors. This report describes a novel ocular finding in patients affected by variants in the BRPF1 gene. METHODS: We performed exome sequencing and deep ocular phenotyping in two unrelated patients (P1, P2) with mild intellectual disability, ptosis, and typical facies. RESULTS: Interestingly, P1 had a Chiari Malformation type I and a subclinical optic neuropathy, which could not be explained by variations in other genes. Having detected a peculiar ocular phenotype in P1, we suggested optical coherence tomography (OCT) for P2; such an exam also detected bilateral subclinical optic neuropathy in this case. DISCUSSION: To date, only a few patients with BRPF1 variants have been described, and none were reported to have optic neuropathy. Since subclinical optic nerve alterations can go easily undetected, our experience highlights the importance of a more detailed ophthalmologic evaluation in patients with BRPF1 variant.

Expanding the Spectrum of Oculocutaneous Albinism: Does Isolated Foveal Hypoplasia Really Exist?

Oculocutaneous albinism is an autosomal recessive disorder characterized by the presence of typical ocular features, such as foveal hypoplasia, iris translucency, hypopigmented fundus oculi and reduced pigmentation of skin and hair. Albino patients can show significant clinical variability; some individuals can present with only mild depigmentation and subtle ocular changes. Here, we provide a retrospective review of the standardized clinical charts of patients firstly addressed for evaluation of foveal hypoplasia and slightly subnormal visual acuity, whose diagnosis of albinism was achieved only after extensive phenotypic and genotypic characterization. Our report corroborates the pathogenicity of the two common TYR polymorphisms p.(Arg402Gln) and p.(Ser192Tyr) when both are located in trans with a pathogenic TYR variant and aims to expand the phenotypic spectrum of albinism in order to increase the detection rate of the albino phenotype. Our data also suggest that isolated foveal hypoplasia should be considered a clinical sign instead of a definitive diagnosis of an isolated clinical entity, and we recommend deep phenotypic and molecular characterization in such patients to achieve a proper diagnosis.