DPAGT1-CDG: Report of Two New Pediatric Patients and Brief Review of the Literature

Introduction

Congenital glycosylation disorders are multisystem diseases with heterogeneous clinical manifestations caused by defects in the synthesis of the glycan moiety of glycoproteins or glycolipids or the binding of glycans to proteins and lipids. DPAGT1 (UDP-GlcNAc: dolichol phosphate N-acetylglucosamine-1-phosphotransferase) is an initiating protein in the biosynthetic pathway of dolichol-linked oligosaccharides required for protein N-glycosylation. Pathogenic variants in DPAGT1 (UDP-GlcNAc: dolichol phosphate N-acetylglucosamine-1-phosphotransferase) gene cause a rare type of congenital glycosylation disorder called DPAGT1-CDG (formerly CDG-Ij) (OMIM #608093). It is a rare autosomal recessive disease or a milder version with congenital myasthenic syndrome known as DPAGT1-CMS. A severe disease course with hypotonia, cataracts, skeletal deformities, resistant epilepsy, intellectual disability, global developmental delay, premature death has been described in most patients with DPAGT1-CDG.

Patient Presentation

We describe two patients with variants in the DPAGT1 gene: an 8-month-old boy with a homozygous, missense DPAGT1:c.339T>G (p.Phe113Leu) novel variant and a 13-year-old female patient with compound heterozygous variants, DPAGT1:c.466C>T (p.Arg156Cys, R156C) and DPAGT1:c.161+5G>A. While the 8-month-old patient was diagnosed with congenital cataract at the age of 1 month, had dysmorphic findings, and epilepsy, clinical symptoms in the other patient appeared later but with more prominent muscle weakness, behavioral disorder, dysmorphic findings, and no epilepsy.

Discussion

Cholinesterase inhibitor therapy was found to be effective in patients against muscle weakness, supporting DPAGT1 deficiency as the underlying etiology. We started pyridostigmine treatment in our patient with more pronounced muscle weakness, and we saw its benefit. We aimed to present our patients diagnosed with DPAGT1-CDG due to different variants in the same gene and different clinical presentations, treatment and to compare them with other patients in the literature.

Immunization status of patients with spinal muscular atrophy receiving nusinersen therapy

BACKGROUND

Children with chronic neurological diseases, including spinal muscular atrophy (SMA), are particularly susceptible to vaccine-preventable infections. We aimed to evaluate the age-appropriate immunization status and its relationship with nusinersen therapy in pediatric patients with SMA.

METHODS

Children with SMA who received nusinersen treatment were included in this cross-sectional prospective study. Data were collected on SMA characteristics, nusinersen therapy, vaccination status according to the National Immunization Program (NIP), administration, and influenza vaccination recommendation.

RESULTS

A total of 32 patients were enrolled. In patients with SMA type 1, the frequency of under-vaccination of hepatitis B, BCG, DTaP-IPV-HiB, OPV, and MMR was statistically higher than in patients with SMA type 2-3 (p<0.001). The influenza vaccine was administered to only 9.3% of patients and was never recommended to 13 (40.6%) parents. The frequency of under-vaccination of hepatitis B, BCG, DTaP-IPV-HiB, OPV, and MMR was statistically higher in patients receiving nusinersen maintenance therapy than in those with loading doses (p<0.001). Physician recommendations for influenza and pneumococcal vaccines were significantly higher in the nusinersen maintenance group (p = 0.029). There was no statistical significance between the groups in terms of administration of influenza and pneumococcal vaccines (p = 0.470).

CONCLUSION

Children with SMA had lower immunization rates and poor compliance with immunization programs. Clinicians should ensure that children with SMA receive the same preventive health measures as healthy children, including vaccinations.

Shared Biological Pathways and Processes in Patients with Intellectual Disability: A Multicenter Study

BACKGROUND

 Although the underlying genetic causes of intellectual disability (ID) continue to be rapidly identified, the biological pathways and processes that could be targets for a potential molecular therapy are not yet known. This study aimed to identify ID-related shared pathways and processes utilizing enrichment analyses.

METHOD

 In this multicenter study, causative genes of patients with ID were used as input for Disease Ontology (DO), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes enrichment analysis.

RESULTS

 Genetic test results of 720 patients from 27 centers were obtained. Patients with chromosomal deletion/duplication, non-ID genes, novel genes, and results with changes in more than one gene were excluded. A total of 558 patients with 341 different causative genes were included in the study. Pathway-based enrichment analysis of the ID-related genes via ClusterProfiler revealed 18 shared pathways, with lysine degradation and nicotine addiction being the most common. The most common of the 25 overrepresented DO terms was ID. The most frequently overrepresented GO biological process, cellular component, and molecular function terms were regulation of membrane potential, ion channel complex, and voltage-gated ion channel activity/voltage-gated channel activity, respectively.

CONCLUSION

 Lysine degradation, nicotine addiction, and thyroid hormone signaling pathways are well-suited to be research areas for the discovery of new targeted therapies in ID patients.