Homozygous mutations in NTRK1 gene underlie congenital insensitivity to pain with anhidrosis in Pakistani families

Congenital insensitivity to pain with anhidrosis is a rare autosomal recessive disorder presenting with loss of pain sensation, thermal sensation defects, and self-mutilating behavior. In the present study, we recruited two consanguineous pedigree showing pain insensitivity symptoms from Pakistan for clinical and molecular investigations. In family A, one female patient displayed classical CIPA symptoms along with microcephaly and severe intellectual disability. During course of the disease, her right foot was amputated and had remarkable dental degeneration and teeth shedding. In family B, one boy presented with classical symptoms of congenital insensitivity to pain with anhidrosis. Blood was collected from both families for molecular studies. Sequencing with the Ilumina Trusight One Sequencing Panel covering 4813 OMIM genes revealed a known homozygous mutation c.2084C>Tp.P695L of NTRK1 in family A and a novel truncated mutation c.2025C>Gp.Y681X in family B. Protein modeling analysis of both mutations (p.P695L and p.Y681X) predicted loss of the rigidity in tyrosine kinase domain of NTRK1 that led to conformational changes as well as deleterious effect on protein function. The known mutation was reported more than a decade ago in a family from Northern Israel and other non-sense mutation is newly identified. It is interested that most of NTRK1 mutations are associated with this domain. This is first ever report of NTRK1 variants in congenital insensitivity to pain with anhidrosis patients from Pakistan