A rare case of congenital insensitivity to pain with anhidrosis.

A 22-month-old girl of consanguineous parents was admitted with a high-grade fever. She was found to have insensitivity to painful stimuli and an absence of perspiration. She also displayed self-mutilating behaviour and was insensitive to cold/hot water on her body. On examination, there was loss of the tip of the tongue, missing teeth, generalised xerosis, and several ulcers at sites of minor trauma. She also had dysplastic nails and digital ulcers. Sensory examination demonstrated a complete lack of awareness of pain and temperature, vibration and fine touch were intact and lacrimation was normal. Differential diagnoses of hereditary sensory and autonomic neuropathy (HSAN), Lesch-Nyhan syndrome, hypohidrotic ectodermal dysplasia and leprosy were considered. Results of routine blood investigations including serum uric acid were normal. On performing clinical exome sequencing, the diagnosis of congenital insensitivity to pain with anhidrosis (CIPA) of autosomal recessive inheritance was confirmed. A novel, predicted to be pathogenic variant detected at exon 16 of the NTRK1 gene resulting in congenital insensitivity to pain with anhidrosis is reported. Abbreviations: CIPA: congenital Insensitivity to pain with anhidrosis; HSAN: hereditary sensory and autonomic neuropathy; NGF: nerve growth factor; NTRK1: neurotrophic tyrosine kinase receptor 1 gene; TrKA: tropomyosin receptor kinase A.