Glycogen Storage Disease Type Ib, also known as von Gierke disease, is a genetic condition where the body lacks an important enzyme called glucose-6-phosphate translocase.
This enzyme helps break down stored sugar (glycogen) into glucose, which our body uses for energy. When this enzyme is missing, the body struggles to maintain normal blood-sugar levels, leading to low blood sugar (hypoglycemia). Additionally, glycogen builds up in the liver, kidneys, and other organs, causing various health problems.
Children with GSDIb might seem healthy at birth, but symptoms usually start becoming noticeable when they start sleeping longer at night. Low blood sugar can cause tiredness, irritability, and seizures. These children often have abnormal levels of certain substances in their body, such as lactic acid, fats, and uric acid. If not diagnosed and managed properly, they can experience severe health crises in their first few months of life. Kids with GSDIb experience delayed growth, and their abdomen might appear swollen due to an enlarged liver. They could also face complications like delayed puberty, weak bones (osteoporosis), and a type of arthritis called gout due to uric acid crystals in their joints. The disease doesn’t affect intellectual abilities, but it can lead to non-cancerous liver tumors, kidney problems, infections, and inflammation in the pancreas and bowels. Treatment involves closely monitoring the affected person’s diet, making sure they eat specific foods and avoid sugars found in fruits and milk. These individuals need to eat small meals every few hours, even during the night, to keep their blood sugar stable. In severe cases, they might require feeding tubes and pumps to maintain their nutrition.
GSDIb is caused by pathogenic (disease-causing) variants in the SLC37A4 gene and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance to have a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background. For example, individuals of Ashkenazi Jewish descent have a 1 in 1254 chance to be a carrier.