Short anagen hair syndrome: association with mono- and biallelic variants in WNT10A and a genetic overlap with male pattern hair loss.

BACKGROUND: Short anagen hair (SAH) is a rare paediatric hair disorder characterized by a short anagen phase, an inability to grow long scalp hair and a negative psychological impact. The genetic basis of SAH is currently unknown. OBJECTIVES: To perform molecular genetic investigations in 48 individuals with a clinical phenotype suggestive of SAH to identify, if any, the genetic basis of this condition. METHODS: Exome sequencing was performed in 27 patients diagnosed with SAH or with a complaint of short, nongrowing hair. The cohort was screened for variants with a minor allele frequency (MAF) < 5% in the general population and a Combined Annotation Dependent Depletion (CADD) score > 15, to identify genes whose variants were enriched in this cohort. Sanger sequencing was used for variant validation and screening of 21 additional individuals with the same clinical diagnosis and their relatives. Genetic association testing of SAH-related variants for male pattern hair loss (MPHL) was performed using UK Biobank data. RESULTS: Analyses revealed that 20 individuals (42%) carried mono- or biallelic pathogenic variants in WNT10A. Rare WNT10A variants are associated with a phenotypic spectrum ranging from no clinical signs to severe ectodermal dysplasia. A significant association was found between WNT10A and SAH, and this was mostly observed in individuals with light-coloured hair and regression of the frontoparietal hairline. Notably, the most frequent variant in the cohort [c.682T>A;p.(Phe228Ile)] was in linkage disequilibrium with four common WNT10A variants, all of which have a known association with MPHL. Using UK Biobank data, our analyses showed that c.682T>A;p.(Phe228Ile) and one other variant identified in the SAH cohort are also associated with MPHL, and partially explain the known associations between WNT10A and MPHL. CONCLUSIONS: Our results suggest that WNT10A is associated with SAH and that SAH has a genetic overlap with the common phenotype MPHL. The presumed shared biologic effect of WNT10A variants in SAH and MPHL is a shortening of the anagen phase. Other factors, such as modifier genes and sex, may also play a role in the clinical manifestation of hair phenotypes associated with the WNT10A locus.

Identification of a novel sporadic U2HR pathogenic variant in a patient with Marie Unna hereditary hypotrichosis.

Marie Unna hereditary hypotrichosis (MUHH) is a rare autosomal dominant hair loss disorder characterized by coarse, wiry, and twisted hair developing during early childhood, and followed by progressive hair loss with puberty. We report a sporadic case of a 4-year-old boy with clinical features suggestive of MUHH, in whom we identified the new pathogenic variant c.67C>T; p.(Gln23*) in U2HR. This finding extends the known spectrum of U2HR variants underlying MUHH and increases genetic information for further genotype-phenotype correlation.

Long-term sirolimus treatment in blue rubber bleb nevus syndrome: Case report and review of the literature.

Blue rubber bleb nevus syndrome is a rare vascular syndrome characterized by continuous eruption of vascular nodules in the skin, mucous membranes, and solid organs due to somatic activating mutations of the angiopoietin receptor TEK gene. It may be complicated by acute life-threatening hemorrhage and localized intravascular coagulation. We report an 11-year-old girl with complicated blue rubber bleb nevus syndrome treated with sirolimus since the age of 2. We review the literature on sirolimus therapy for children with blue rubber bleb nevus syndrome.