Case Report: Identification of Two Variants of ALG13 in Families With or Without Seizure and Binocular Strabismus: Phenotypic Spectrum Analysis

Pediatric Anesthetic Management of a Patient With an ALG-13 Gene Mutation, a Rare Congenital Disorder of Glycosylation

Congenital disorders of glycosylation are rare and present a challenge in management due to interactions with intraoperative medications. We present safe and successful anesthetic management of a pediatric patient with an ALG-13 gene mutation.

ALG13-Related Epilepsy: Current Insights and Future Research Directions

The ALG13 gene encodes a subunit of the uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc) transferase enzyme, which plays a key role in the N-linked glycosylation pathway. This pathway involves the attachment of carbohydrate structures to asparagine (Asn) residues in proteins within the endoplasmic reticulum, by which N-glycosylated proteins produced participate a wide range of processes such as electrical gradients formation and neurotransmission. Mutations in the ALG13 gene have been identified as a causative factor for congenital disorders of glycosylation (CDG) and have been frequently associated with epilepsy in affected individuals. Several studies have demonstrated a strong correlation between abnormal N-glycosylation due to ALG13 deficiency and the onset of epilepsy. Despite these findings, the precise role of ALG13 in the pathogenesis of epilepsy remains unclear. This review provides a comprehensive overview of the current literature on ALG13-related disorders, with a focus on recent evidence regarding its role in epilepsy development and progression. Future research directions are also proposed to further elucidate the molecular mechanisms underlying this association.

Similarity of Phenotype in Three Male Patients With the c.320A>G Variant in ALG13: Possible Genotype-Phenotype Correlation

BACKGROUND

Congenital disorders of glycosylation (CDG) are a group of neurometabolic diseases that result from genetic defects in the glycosylation of proteins and/or lipids. Multiple pathogenic genes contribute to the varying reported phenotypes of individuals with CDG-1 syndromes, most of which are inherited as autosomal recessive traits, although X-linked inheritance has also been reported. Pathogenic variants in the asparagine-linked glycosylation 13 homolog (ALG13) gene have been implicated in the aetiology of developmental and epileptic encephalopathy (DEE) 36 (OMIM:*300776, DEE36). The NM_001099922.3:c.320A>G; p.(Asn107Ser) variant is the most frequently described pathogenic variant in ALG13, with 59 females and 2 males with this variant reported to date.

METHODS

We report on a male with a de novo, hemizygous variant in ALG13: c.320A>G; p.(Asn107Ser), whose phenotype resembles that of two previously reported males with the same variant.

RESULTS

All three males have a de novo mutation, infantile spasms, DEE, drug-resistant epilepsy, intellectual disability, dysmorphic findings, recurrent infections, skeletal anomalies, brain abnormalities and a movement disorder: a phenotype not consistently reported in males with other pathogenic variants in ALG13.

CONCLUSION

The similarity of phenotype in the three males with the c.320A>G variant in ALG13, suggests a possible genotype-phenotype correlation.

Identification of four novel variants in the CDH23 gene from four affected families with hearing loss

Background: Hearing loss (HL) is the most common form of sensory disorder in humans. Molecular diagnosis of HL is important for genetic counseling for the affected individuals and their families.

Methods: To identify potential genetic causes, we performed whole-exome sequencing and related biomedical informatics for 351 non-syndromic HL patients and their family members.

Results: In the present study, we report the identification of four compound heterozygous variants in the CDH23 gene from four affected families, including four novel variants (c.995C>A, p.T332K; c.2159G>A, p.R720Q; c.5534A>G, p.N1845S, and c.7055-1G>C) and two frequently reported variants (c.719C>T, p.P240L and c.4762C>T, p.R1588W).

Conclusion: Our findings significantly expanded the mutation spectrum of CDH23-associated autosomal recessive hearing loss.