Syrian child carrying multiple pathogenic variants in MBOAT7 and MT-TS1 genes: a case report on neurodevelopmental phenotypes and mitochondrial inheritance

Abstract

Introduction: The authors identify two patterns of inheritance in a Syrian child from consanguineous parents. The membrane-bound O-acyltranferase domain-containing7 (MBOAT7) gene encodes Lysophosphatidylinositol acyltranferase (LPIAT1), which is responsible for the neurodevelopment of the brain cortex. Patients with MBOAT7 variants exhibit pathogenic nervous manifestations such as global developmental delays affecting speech and motor function, intellectual disability (ID), poor coordination, and seizures, with or without MRI abnormalities. MT_TS1, the mitochondrial tRNASer(UCN) gene, is a hotspot for pathogenic mutations causing variable mitochondrial phenotypes, including hearing impairment (HI), ataxia and cognitive impairment. Clinical presentation: The authors present a case of a 4-year-old child with motor and speech delay, truncal hypotonia, visual tic, poor coordination, autistic features and generalized seizures at 7 months of age. After normal results from lab tests and MRI imaging, along with the family’s history of neurological disorders, genetic analysis was necessary to diagnose and assess the possibility of genetic counselling. Next-generation sequencing (NGS) showed two variable variants in the MBOAT7 and MT-TS1 genes. The first mutation is a homozygous variant of uncertain significance in the MBOAT7 gene, associated with the autosomal recessive Mental retardation type 57. The second variant is a heteroplasmic pathogenic variant in the MT-TS1 gene, indicative of mitochondrial disorders. Conclusion: The presence of the MBOAT7 and MT-TS1 gene variants in the same child is noteworthy. The authors must keep genetic mutations of MBOAT7 and MT-TS1 gene in mind as a differential diagnosis for intellectual disability, seizures and autistic features in children, especially in consanguineous families.