Phacomatosis spilorosea: visual diagnosis and associated pathologies of a rare entity

Somatic GNA11/GNAQ variants in a cohort of Chinese children with phakomatosis pigmentovascularis

Importance

Postzygotic mutations in the GNAQ/GNA11 genes, which encode the G-protein nucleotide binding protein alpha subunits, have been identified in patients with phakomatosis pigmentovascularis (PPV). However, little is known about the Chinese population.

Objective

To identify pathogenic mutations in pediatric patients with PPV within the Chinese population.

Methods

We performed whole-exome sequencing (WES) using skin lesion tissues from pediatric patients diagnosed with PPV. Additionally, ultradeep-targeted sequencing was conducted to validate the somatic mutations. A genotype-phenotype correlation was analyzed by integrating data from previous reports with the findings of the present study.

Results

Thirteen patients were enrolled, all diagnosed with the cesioflammea type of PPV, except for one patient with an unclassifiable type. We identified somatic GNA11 c.547C>T (p.R183C) variant in seven patients and GNAQ c.548G>A (p.R183Q) in four patients, with low allelic fractions ranging from 2.1% to 8.6% through ultradeep sequencing. Besides, a GNAQ c.548G>A (p.R183Q) variant was detected through targeted sequencing in one of two patients who did not exhibit detectable variants via WES. The genotype-phenotype correlation analysis, involving 15 patients with a GNA11 variant and 10 with a GNAQ variant, revealed that facial capillary malformation (87% vs. 50%, P = 0.075) and ocular melanocytosis (80% vs. 40%, P = 0.087) appeared to be more frequent in patients with GNA11 mutation compared to those with GNAQ mutations. All four patients diagnosed with cesiomarmorata type or overlapping cesioflammea and cesiomarmorata type PPV carried the GNA11 variant.

Interpretation

Our study demonstrated that the majority of PPV patients in the Chinese population carried a postzygotic variant of GNAQ/GNA11, thus further confirming the pathogenic role of GNAQ/GNA11 mosaicism in the development of PPV cesioflammea type.

Ocular manifestations in phakomatosis pigmentovascularis: Current concepts on pathogenesis, diagnosis, and management

Phakomatosis pigmentovascularis is a rare congenital multisystemic disease with variable manifestations where a vascular malformation of the skin is associated with a pigmentary nevus. Ocular involvement includes glaucoma, choroidal hemangioma, and pigmentary alterations that predispose to uveal melanoma. Diagnosis is made on clinical grounds, although recent advances in molecular genetics have better clarified the etiopathogenesis of the condition. The advent of improved imaging techniques such as enhanced depth imaging spectral domain optical coherence tomography has provided new insight into the ocular alterations, enabling better follow-up of patients. We review the ophthalmic manifestations of the disease with an update on etiopathogenesis and current management strategies.