The β9 Loop Domain of PA-PLA1α Has a Crucial Role in Autosomal Recessive Woolly Hair/Hypotrichosis

The study identified a crucial heterozygous missense mutation, p.Asp207His, in the β9-loop domain of PA-PLA1α in a 3-year-old Japanese girl with autosomal recessive woolly hair/hypotrichosis (ARWH/H). This mutation led to a significant reduction in the enzyme's hydrolytic activity and a complete loss of its ability to activate LPA6, which is essential for normal hair growth. The mutation was absent in 100 normal unrelated individuals, underscoring its potential contribution to the ARWH/H phenotype and the importance of the β9-loop domain in enzyme function.