Novel WDR۶۲ and MTR Variants in a Patient With Autosomal Recessive Primary Microcephaly-۲ With Polymicrogyria and Homocystinuria-Megaloblastic Anemia

Background: Autosomal recessive primary microcephaly-۲ (MCPH۲) is a rare genetic disorder with clinical and genetic heterogeneity. This study aimed to perform high-throughput whole-exome sequencing (WES) to facilitate the diagnosis of the genetic variants responsible for MCPH۲ and the comorbidities.Materials and Methods: The WES was performed for a ۳-year-old boy with primary microcephaly-۲ and homocystinuria-megaloblastic anemia in a consanguineous family. Sequencing and variant calling was conducted by standard bioinformatics tools. Filtering was performed to prioritize novel variants. Finally, the effect of variants on the protein structure and function was assessed using web prediction tools.Results: Using WES, two novel homozygous variants and three novel homozygous variants were identified in the WDR۶۲ and MTR genes as the causes of MCPH۲ and homocystinuria-megaloblastic anemia in the affected child, respectively. These frameshift insertion variants are classified as pathogenic and affect the structure and feature of the WDR۶۲ and MTR proteins by changing amino acid sequence and causing nonsense-mediated RNA decay (NMD).Conclusion: Magnetic resonance imaging (MRI) supported polymicrogyria and impaired cerebral cortical development in the affected child. WDR۶۲ as a causative gene plays an essential role in cerebral cortical development, and its pathogenic disease-causing variants are considered as causing factors for MCPH۲. Homocystinuria-megaloblastic anemia was a comorbidity associated with microcephaly in this patient, and its variants were confirmed by WES. Overall, performing WES is a necessary and accurate way to rapidly identify the exact causative genetic variants in MCPH۲ and the homocystinuria-megaloblastic anemia and manage the disease.

کلیدواژه ها:

MCPH۲ ، Whole Exome Sequencing ، WDR۶۲ gene ، MTR gene