Clinical Characteristics and Genetic Analysis of Klippel-Feil Syndrome / 中国医学科学院学报

Objective To summarize clinical characteristics and investigate possible pathogenic gene of Klippel-Feil syndrome(KFS)by the self-designed multigene panel sequencing,so as to decipher the molecular basis for early diagnosis and targeted therapy.Methods From January 2015 to December 2018,we consecutively recruited 25 patients who were diagnosed with KFS in Peking Union Medical College Hospital.The demographic information,clinical manifestations,physical examination and radiological assessments were analyzed.Multigene panel sequencing was performed after DNA extraction from peripheral blood.The possible pathogenic mutations of KFS were explored on the basis of bioinformatics analysis.Results The KFS cohort consisted of 25 patients,including 15 males and 10 females,with a mean age of(12.9±7.3)years.Limited cervical range of motion was the most common clinical feature(12 cases,48%).Based on the Samartzis classification,the proportion of patients suffered from short neck(P=0.031)and limited cervical range of motion(P=0.026)in type Ⅲ KFS was significantly higher than that in type Ⅱ and type Ⅰ KFS.Panel sequencing detected a total of 11 pathogenic missense mutations in eight patients,including COL6A1,COL6A2,CDAN1,GLI3,FLNB,CHRNG,MYH3,POR,and TNXB.There was no pathogenic mutation found in five reported pathogenic genes(GDF6,MEOX1,GDF3,MYO18B and RIPPLY2)associated with KFS.Conclusions Our study has shown that patients with multiple contiguous cervical fusions are more likely to manifest short neck,limited cervical range of motion,and clinical triad.Therefore,these patients need additional attention and follow-up.Our analysis highlights novel KFS-related genetic variants,such as COL6A and CDAN1,extending the spectrum of known mutations contributing to this syndrome and providing a basis for elucidating the pathogenesis of KFS.

Application of Multigene Panel Sequencing in Patients with Prolonged Rate-corrected QT Interval and No Pathogenic Variants Detected in KCNQ1, KCNH2, and SCN5A

Long QT syndrome (LQTS) is an inherited cardiac disease characterized by a prolonged heart rate-corrected QT (QTc) interval. We investigated the genetic causes in patients with prolonged QTc intervals who were negative for pathogenic variants in three major LQTS-related genes (KCNQ1, KCNH2, and SCN5A). Molecular genetic testing was performed using a panel including 13 LQTS-related genes and 67 additional genes implicated in other cardiac diseases. Overall, putative genetic causes of prolonged QTc interval were identified in three of the 30 patients (10%). Among the LQTS-related genes, we detected a previously reported pathogenic variant, CACNA1C c.1552C>T, responsible for cardiac-only Timothy syndrome. Among the genes related to other cardiac diseases, a likely pathogenic variant, RYR2 c.11995A>G, was identified in a patient with catecholaminergic polymorphic ventricular tachycardia. Another patient who developed dilated cardiomyopathy with prolonged QTc interval was found to carry a likely pathogenic variant, TAZ c.718G>A, associated with infantile dilated cardiomyopathy. Comprehensive screening of genetic variants using multigene panel sequencing enables detection of genetic variants with a possible involvement in QTc interval prolongation, thus uncovering unknown molecular mechanisms underlying LQTS.