Type III Nonketotic Hyperglycinemia (NKH) is a rare genetic disorder that affects the central nervous system and disrupts the breakdown of the amino acid glycine. Glycine is an essential amino acid that plays a crucial role in the normal functioning of the brain and spinal cord. In individuals with Type III NKH, a specific enzyme called glycine decarboxylase is defective, leading to an accumulation of glycine in the body.
Symptoms of Type III NKH typically appear in infancy or early childhood and can vary widely in their severity. These symptoms may include developmental delays, intellectual disabilities, seizures, hypotonia (low muscle tone), difficulty breathing, and feeding problems. Additionally, affected individuals may exhibit abnormal movements, such as tremors or jerking motions. In some cases, Type III NKH can also cause life-threatening complications, including brain abnormalities or seizures that are difficult to control.
Type III NKH is diagnosed through genetic testing, which identifies mutations in the genes responsible for the production of glycine decarboxylase. Treatment options for Type III NKH are limited and primarily aim to manage symptoms and provide supportive care. Medications such as benzoate and dextromethorphan may be prescribed to help lower glycine levels in the body. Additionally, physical and occupational therapy may be beneficial in promoting mobility and development.
Type III NKH is an inherited disorder, usually following an autosomal recessive pattern, which means that affected individuals inherit two copies of the mutated gene, one from each parent, resulting in the impaired enzyme function. Genetic counseling is recommended for individuals or families affected by Type III NKH to understand the risks of passing on the disorder to future generations.
