[Mental retardation, hypogonadism, epilepsy, white matter lesions and hyperhomocysteinemia in a family].

OBJECTIVE

To detect SCN4A gene mutation in a pedigree with paramyotonia congenita in order to facilitate genetic counseling and assisted reproduction.

METHODS

Clinical data of the family was collected. DNA was extracted from peripheral blood samples. Potential mutation of the SCN4A gene was screened using PCR-Sanger sequencing. Potential mutation was detected in 3 affected relatives, 4 unaffected relatives and 100 unrelated healthy controls. Bioinformatics software was used to predict the effect of mutation on the protein function and conservation of the sequence at the mutation site across various species.

RESULTS

A novel missense mutation c.4427T>C (p.Met1476Thr) was detected in the exon 24 of the SCN4A gene in the proband and other 3 affected relatives, but not in 4 unaffected relatives and 100 unrelated controls. Bioinformatic analysis indicated that the codon is highly conserved across various species, and that the mutation has caused damage to the structure and function of SCN4A protein.

CONCLUSION

The c.4427 T>C (p.Met1476Thr) mutation of the SCN4A gene may contribute to the paramyotonia congenita. Detection of SCN4A gene mutation is an effective method for the diagnosis of paramyotonic congenita.