Rapid Identification of Pathogenic Variants in Two Cases of Charcot-Marie-Tooth Disease by Gene-Panel Sequencing

• Published in: International journal of molecular sciences Vol. 18; no. 4; p. 770
• Main Authors: Ho, Chi-Chun, Tai, Shuk-Mui, Lee, Edmond Chi-Nam, Mak, Timothy Shin-Heng, Liu, Timothy Kam-Tim, Tang, Victor Wai-Lun, Poon, Wing-Tat
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 05.04.2017; MDPI
• Subjects: Adolescent; Case Report; Champagne; Charcot-Marie-Tooth disease; Charcot-Marie-Tooth disease (CMT); Charcot-Marie-Tooth Disease - genetics; Diagnosis; Diagnostic systems; Feet; Female; gene panel; Genes; Genetic Predisposition to Disease; Genetic screening; Genetic Testing - methods; hereditary motor and sensory neuropathy (HMSN); Humans; Male; Muscles; Mutation; next-generation sequencing (NGS); Parents; Pathogenesis; pathogenic variants; Patients; Peripheral neuropathy; Phenotyping; Pregnancy; Thinning; Walking; Young Adult; hereditary motor and sensory neuropathy (HMSN); Charcot-Marie-Tooth disease (CMT); next-generation sequencing (NGS); pathogenic variants; gene panel
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms18040770

Charcot-Marie-Tooth disease (CMT) is a common inherited peripheral neuropathy affecting up to 1 in 1214 of the general population with more than 60 nuclear genes implicated in its pathogenesis. Traditional molecular diagnostic pathways based on relative prevalence and clinical phenotyping are limited by long turnaround time, population-specific prevalence of causative variants and inability to assess multiple co-existing variants. In this study, a CMT gene panel comprising 27 genes was used to uncover the pathogenic mutations in two index patients. The first patient is a 15-year-old boy, born of consanguineous parents, who has had frequent trips and falls since infancy, and was later found to have inverted champagne bottle appearance of bilateral legs and foot drop. His elder sister is similarly affected. The second patient is a 37-year-old woman referred for pre-pregnancy genetic diagnosis. During early adulthood, she developed progressive lower limb weakness, difficulties in tip-toe walking and thinning of calf muscles. Both patients are clinically compatible with CMT, have undergone multiple genetic testings and have not previously received a definitive genetic diagnosis. Patients 1 and 2 were found to have pathogenic homozygous :NM_001540:c.250G>A (p.G84R) variant and heterozygous :NM_018972:c.358C>T (p.R120W) variant, respectively. Advantages and limitations of the current approach are discussed.