Type II Nonketotic Hyperglycinemia (NKH) is a rare, progressive, and inherited metabolic disorder that affects the central nervous system. It is characterized by a deficiency of the glycine cleavage enzyme system, leading to the accumulation of glycine, an amino acid, in the brain and spinal cord.
During normal metabolism, glycine is broken down by the glycine cleavage enzyme system. However, in individuals with Type II NKH, this enzyme system does not function properly, resulting in an inability to break down glycine effectively. As a result, glycine accumulates at toxic levels in the brain and spinal cord, leading to severe neurological symptoms and brain damage.
Symptoms of Type II NKH usually appear shortly after birth or within the first few months of life. These symptoms may include lethargy, hypotonia (low muscle tone), seizures, difficulty swallowing, breathing difficulties, and developmental delays. If left untreated, the condition can lead to severe intellectual disability and life-threatening complications.
The diagnosis of Type II NKH is usually confirmed through genetic testing, which identifies mutations in the genes responsible for the glycine cleavage enzyme system. Currently, there is no cure for Type II NKH, and treatment primarily focuses on managing symptoms and providing supportive care. This may include medications to control seizures, physical and occupational therapy to support development and mobility, and a specialized diet low in protein and glycine to help reduce glycine levels.
In summary, Type II Nonketotic Hyperglycinemia is a rare metabolic disorder that causes the toxic accumulation of glycine in the brain and spinal cord. It leads to severe neurological symptoms and developmental delays if left untreated. Treatment primarily focuses on symptom management and supportive care.
