AUTHOR=Skrypnyk Cristina , Husain Aseel Ahmed , Hassan Hisham Y. , Ahmed Jameel , Darwish Abdulla , Almusalam Latifa , Ben Khalaf Noureddine , Al Qashar Fahad 

TITLE=Case report: Homozygous variants of NEB and KLHL40 in two Arab patients with nemaline myopathy

JOURNAL=Frontiers in Genetics

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2023.1098102

DOI=10.3389/fgene.2023.1098102

ISSN=1664-8021

ABSTRACT=<p><bold>Objective:</bold> Nemaline myopathies are a heterogeneous group of congenital myopathies caused by mutations in different genes associated with the structural and functional proteins of thin muscular filaments. Most patients have congenital onset characterized by hypotonia, respiratory issues, and abnormal deep tendon reflexes, which is a phenotype encountered in a wide spectrum of neuromuscular disorders. Whole-exome sequencing (WES) contributes to a faster diagnosis and facilitates genetic counseling.</p><p><bold>Methods:</bold> Here, we report on two Arab patients from consanguineous families diagnosed with nemaline myopathy of different phenotype spectrum severities.</p><p><bold>Results:</bold> Clinical assessment and particular prenatal history raised suspicion of neuromuscular disease. WES identified homozygous variants in <italic>NEB</italic> and <italic>KLHL40</italic>. Muscle biopsy and muscle magnetic resonance imaging studies linked the genetic testing results to the clinical phenotype. The novel variant in the <italic>NEB</italic> gene resulted in a classical type 2 nemaline myopathy, while the <italic>KLHL40</italic> gene variant led to a severe phenotype of nemaline myopathy, type 8. Both patients were identified as having other gene variants with uncertain roles in their complex phenotypes.</p><p><bold>Conclusions:</bold> This study enriches the phenotypic spectrum of nemaline myopathy caused by <italic>NEB</italic> and <italic>KLHL40</italic> variants and highlights the importance of detailed prenatal, neonatal, and infancy assessments of muscular weakness associated with complex systemic features. Variants of uncertain significance in genes associated with nemaline myopathy may be correlated with the phenotype. Early, multidisciplinary intervention can improve the outcome in patients with mild forms of nemaline myopathies. WES is essential for clarifying complex clinical phenotypes encountered in patients from consanguineous families. Targeted carrier screening of extended family members would enable accurate genetic counseling and potential genetic prevention.</p>