Heterozygous pathogenic variants in DNM1 are linked to an autosomal dominant form of epileptic encephalopathy. Recently, homozygous loss-of-function variants in DNM1 were reported to cause an autosomal recessive form of developmental and epileptic encephalopathy in unrelated patients. Here, we investigated a singleton from a first-degree cousin marriage who presented with facial dysmorphism, global developmental delay, seizure disorder, and nystagmus. To identify the involvement of any likely genetic cause, diagnostic clinical exome sequencing was performed. Comprehensive filtering revealed a single plausible candidate variant in DNM1. Sanger sequencing of the trio, the patient, and her parents, confirmed the full segregation of the variant. The variant is a deletion leading to a premature stop codon and is predicted to cause a protein truncation. Structural modeling implicated a complete loss of function of the Dynamin 1 (DNM1). Such mutation is predicted to impair the nucleotide binding, dimer formation, and GTPase activity of DNM1. Our study expands the phenotypic spectrum of pathogenic homozygous loss-of-function variants in DNM1.

Background: Chromosomal aneuploidy, characterized by an abnormal number of chromosomes, represents a significant cause of genetic disorders. While karyotyping and chromosomal microarray analysis (CMA) are established diagnostic approaches, they are limited by cost and extended turnaround times. Advances in exome sequencing (ES) bioinformatics enable detection of chromosomal aneuploidy alongside single-nucleotide variant analysis. This study explores the utility of clinical ES for the detection of aneuploidies. Method: We analyzed exome sequencing data (2023–2024) from samples positive for Trisomy 21 (n = 27), Trisomy 18 (n = 4), Turner syndrome (n = 3), and Klinefelter syndrome (n = 2) from our clinical ES cohort (n = 10,000). Results: The results obtained were concordant with copy number variants (CNVs) identified by clinical testing. Conclusion: In conclusion, our findings suggest that exome sequencing offers a rapid and viable approach for the detection of chromosomal aneuploidy, potentially reducing turnaround time and associated costs.