CDG type Ia and congenital cytomegalovirus infection: two coexisting conditions

PMM2-CDG and nephrotic syndrome: A case report

Congenital disorders of glycosylation (CDG) are a group of rare metabolic diseases, characterized by a defect in the protein glycosylation process. Enzymes involved in this metabolic mechanism have ubiquitous distribution; thus, their alteration can cause systemic involvement and considerable phenotypic variability. Nephrotic syndrome (NS) is a clinical condition characterized by edema, hypoalbuminemia, hyperlipidemia, and proteinuria. We hereby report the case of a girl with central hypotonia, epilepsy, and severe psychomotor delay diagnosed with phosphomannomutase 2 deficiency (PMM2-CDG) after presenting with nephrotic syndrome at age 4 years.

International clinical guidelines for the management of phosphomannomutase 2-congenital disorders of glycosylation: Diagnosis, treatment and follow up

Phosphomannomutase 2 (PMM2-CDG) is the most common congenital disorder of N-glycosylation and is caused by a deficient PMM2 activity. The clinical presentation and the onset of PMM2-CDG vary among affected individuals ranging from a severe antenatal presentation with multisystem involvement to mild adulthood presentation limited to minor neurological involvement. Management of affected patients requires a multidisciplinary approach. In this article, a systematic review of the literature on PMM2-CDG was conducted by a group of international experts in different aspects of CDG. Our managment guidelines were initiated based on the available evidence-based data and experts' opinions. This guideline mainly addresses the clinical evaluation of each system/organ involved in PMM2-CDG, and the recommended management approach. It is the first systematic review of current practices in PMM2-CDG and the first guidelines aiming at establishing a practical approach to the recognition, diagnosis and management of PMM2-CDG patients.

Renal involvement in PMM2-CDG, a mini-review

Phosphomannomutase 2 deficiency (PMM2-CDG) is the most common N-linked glycosylation disorder. The majority of patients present with a multisystem phenotype, including central nervous system involvement, hepatopathy, gastrointestinal and cardiac symptoms, endocrine dysfunction and abnormal coagulation. Renal abnormalities including congenital malformations and altered renal function are part of the multisystem manifestations of congenital disorders of glycosylation. We reviewed the literature on 933 patients with molecularly and/or enzymatically confirmed PMM2 deficiency to evaluate the incidence of renal involvement in PMM2-CDG. Renal abnormalities were reported in 56 patients. Congenital abnormalities were present in 41 out of these 55. Cystic kidney and mild proteinuria were the most common findings. One of the most severe renal manifestations, congenital nephrotic syndrome, was detected in 6 children. Renal manifestations were not associated with the presence of specific PMM2 alleles. This review summarizes the reported renal abnormalities in PMM2-CDG and draws attention to the pathophysiological impact of abnormal glycosylation on kidney structure and function.