Genetic diagnosis of Jordanian patients with glycogen storage diseases

Glycogen storage diseases (GSDs) are a group of hereditary metabolic disorders caused by defects in biosynthesis, and storage of glycogen that affect various organs, such as liver, muscles, and heart. Approximately 29 genes are implicated in GSDs. This study aimed to identify the genetic variants causing GSDs in Jordanian patients. Twenty patients with clinically suspected GSD were studied. Clinical data were reviewed and whole exome sequencing (WES) was conducted. Variants were validated, and the carrier status of the parents was confirmed by Sanger sequencing. Following genetic counseling, seven families opted for prenatal diagnosis (PND), and one of them proceeded with preimplantation genetic diagnosis (PGD) after the previous unsuccessful PND. Thirteen putative disease-causing variants in nine genes (AGL, GAA, GBE1, G6PC, PHKA2, PHKB, PHKG2, SLC2A2, and SLC37A4) were identified. Three of these variants have never been published. GSDII was the most common type (25%), followed by GSDIa (20%), GSDIb (15%), GSDIII and GSDIXC (10% each), and GSDIV, GSDIXa, GSDIXb, and GSDXI (5% each). Out of eight PND cases, two fetuses were affected, whereas the rest were unaffected. PGD identified two normal embryos out of the 13 tested, resulting in the successful birth of a healthy son. This study expands the genetic spectrum of GSD-associated genes and highlights the role of consanguinity in disease prevalence. WES has proven effective for the diagnosis of GSDs, facilitating accurate disease identification, early treatment, and management. These findings are valuable for genetic counseling, PND, and PGD as effective tools for disease prevention and family planning.