The third case of Marbach-Rustad progeroid syndrome caused by a de novo LEMD2 variant.

Marbach-Rustad progeroid syndrome is an extremely rare disease caused by a heterozygous variant in the LEMD2 gene. To date, only two patients and one LEMD2 pathogenic variant have been reported in Marbach-Rustad progeroid syndrome. Here we describe the third case of Marbach-Rustad progeroid syndrome worldwide, which is also the first case in China. The proband was affected with premature birth, failed to thrive, facial abnormalities, feeding difficulties, skull defects and delayed motor milestones, but had a normal intelligence and speech. Whole exome sequencing (WES) initially did not find a phenotype-causing variant when the proband was 1 year of age. The reanalysis of WES data 4 years later revealed the proband harbored a de novo heterozygous c.1436C>T(p.Ser479Phe) variant in the LEMD2 gene, which is known responsible for Marbach-Rustad progeroid syndrome. Sanger sequencing confirmed the presence of this variant in the proband and absence in his parents and two elder sisters. Our study provides accurate clinical diagnosis for the proband and adds a new patient with Marbach-Rustad progeroid syndrome. Our study suggests the LEMD2 c.1436C>T(p.Ser479Phe) variant as a hotspot. Our work also indicates reanalysis of WES data of negative cases might identify pathogenic variant and improve diagnostic efficiency.