Molecular genetic analysis in 21 Chinese families with congenital insensitivity to pain with or without anhidrosis

Background and purpose Hereditary sensory and autonomic neuropathies (HSANs) are a group of clinically and genetically heterogeneous neurological disorders characterized by sensory dysfunctions. Here, 21 affected Chinese families are reported, including 19 with congenital insensitivity to pain with anhidrosis (CIPA; namely HSAN IV) and two with congenital insensitivity to pain (CIP; namely HSAN IID) caused by biallelic variations in NTRK1 and SCN9A , respectively, aiming to identify causative variants in these families and compare how different variants in NTRK1 affect the function of tropomyosin receptor kinase A (TrkA). Methods Recombinant plasmids harboring the wild‐type and six mutant alleles (p.Gln216*, p.Glu584Lys, p.Leu595Arg, p.Pro684Leu, p.Val709Leu and p.Arg765Cys) of NTRK1 cDNA were constructed and transfected into HEK293 cells. Results The results suggested that the five missense variants only presented a subtle influence on the expression level and glycosylation of TrkA but compromised the receptor phosphorylation. Our findings also suggested that a synonymous variant c.219C>T in NTRK1 may cause aberrant splicing, indicating a potential novel pathogenic mechanism of CIPA. Furthermore, gross deletion of SCN9A was first associated with CIP. Conclusions This study identified multiple forms of variants responsible for CIPA/CIP in the Chinese population and might provide new insights into the pathogenesis of CIPA.