Clinical phenotype and genetic mutation of one case with head tremor and cerebellar atrophy

Objective To make the diagnosis for a patient presented with head tremor and cerebellar atrophy by integrating clinical features and accessory examination with genetic testing and to explore the interpretation of genetic testing results.  Methods A 30-year-old male patient's medical information, clinical pheontype, family history and accessory examinations were collected. The next?generation sequencing (NGS) of exons in 3994 causative genes of Mendelian inheritance diseases and the family tree verification were carried out. China Human Phenotype Ontology (CHPO), Phenomizer, Ensembl and Online Mendelian Inheritance in Man (OMIM) database were used to interpret the genetic test results.  Results The patient carried heterozygous mutation of spinocerebellar ataxia type 19 (SCA19) related KCND3 gene c.1057A > G (p. Ser353Gly), but his parents did not carry this mutation. The patient also carried heterozygous mutation of parkinsonism type 20 (PARK20) related SYNJ1 gene c.4436C > T (p.Thr1479Ile) which was also seen in his mother. Phenotypic similarity analysis showed the patient's phenotype was correspond with the phenotype of SCA19, and the variation locus of KCND3 gene c.1057A > G was highly conservative with homologous gene in different species. Conclusions By means of the integration of clinical phenotype with the result of genetic test, KCND3 gene c.1057A > G (p.Ser353Gly) carried in the patient is the pathogenic mutation. DOI: 10.3969/j.issn.1672-6731.2017.07.007