Novel FERMT3 and PTPRQ Mutations Associated with Leukocyte Adhesion Deficiency-III and Sensorineural Hearing Loss

Leukocyte adhesion deficiency-III (LAD-III) is a rare genetic disease caused by defective integrin activation in hematopoietic cells due to mutations in the FERMT3 gene. The PTPRQ gene encodes the protein tyrosine phosphatase receptor Q and is essential for the normal maturation and function of hair bundle in the cochlea. Homozygous PTPRQ mutations impair the stereocilia in hair cells which lead to nonsyndromic sensorineural hearing loss (SNHL) with vestibular dysfunction. Here, we report two novel pathogenic homozygous mutations found in two genes, FERMT3 and PTPRQ, in a Brazilian patient with LAD-III and SNHL, which may develop our understanding of the phenotype–genotype correlation and prognosis of patients with these rare diseases.