Key result
Novel homozygous SPEG variant links to mild congenital myopathy and intellectual disability without cardiomyopathy.
Why the study?
Mutations in the SPEG gene are an extraordinarily rare cause of centronuclear myopathies, and the phenotypic spectrum is not fully defined.
Case Report (n=1)
This case report expands the phenotypic spectrum of SPEG-related congenital myopathy by associating it with mild intellectual disability and no dilated cardiomyopathy.
Hypothesis-generating for expanded SPEG myopathy phenotypes; larger cohorts needed to confirm associations before clinical consideration.
Centronuclear myopathies (CNMs) are a subgroup of congenital myopathies (CMs) characterized by muscle weakness, genetic heterogeneity, and predominant type 1 fibers and increased central nuclei in muscle biopsy. Mutations in CNM-causing genes such as MTM1, DNM2, BIN1, RYR1, CACNA1S, TTN, and extraordinary rarely SPEG (striated muscle preferentially expressed protein kinase) have been identified for about 60-80% of patients. Herein, we report a case of CM due to a novel variation in the SPEG gene, manifested by mild neonatal hypotonia, muscle weakness, delayed motor milestones, and ophthalmoplegia, without dilated cardiomyopathy. We identified a novel variation [c.153C>T (p.Asn51=) in exon 1] in the SPEG gene with whole-exome sequencing and confirmed by Sanger sequencing. Mild intellectual disability has not been associated with SPEG-related CM in the previous reports. We suggest that this report expands the phenotypic spectrum of SPEG-related CM, and further case reports are required to expand the genotype-phenotype correlations.
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Yıldırım et al. (2021) conducted a case report in Congenital myopathy (n=1). SPEG gene variation c.153C>T (p.Asn51=) was evaluated on Clinical phenotype. A novel homozygous variation in the SPEG gene (c.153C>T) was identified in a 7-year-old boy, expanding the phenotypic spectrum to include mild congenital myopathy with intellectual disability and no dilated cardiomyopathy.
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