E72.51 Non-ketotic hyperglycinemia

Name of the Condition

• Non-ketotic hyperglycinemia (ICD-10 Code: E72.51)

Summary

Non-ketotic hyperglycinemia is a rare genetic disorder affecting the body’s ability to metabolize glycine, a non-essential amino acid. This condition disrupts normal glycine breakdown, leading to its accumulation in the blood, cerebrospinal fluid, and tissues. Clinical effects primarily involve the nervous system, resulting in severe neurological impairment.

Causes

The disorder is caused by genetic mutations that impair the glycine cleavage system, a key enzyme complex responsible for glycine metabolism. Most cases are inherited in an autosomal recessive pattern, requiring two mutated copies of the gene for the condition to manifest. These mutations disrupt the biochemical pathway, preventing proper glycine breakdown.

Risk Factors

• Family history of non-ketotic hyperglycinemia.
• Consanguinity (parents who are close relatives) increasing the likelihood of inheriting recessive mutations.
• Ethnic or geographic prevalence of specific genetic variants in certain populations.

Symptoms

• Severe neurological symptoms such as lethargy, seizures, or coma.
• Developmental delays or intellectual disability.
• Respiratory difficulties or apnea.
• Poor feeding or failure to thrive.

Diagnosis

Diagnosis involves measuring glycine levels in blood and cerebrospinal fluid, typically showing elevated glycine in both. Additional testing may include genetic analysis to identify mutations in the glycine cleavage system genes. Neuroimaging or electroencephalography (EEG) may be used to assess neurological involvement.

Treatment Options

Treatment focuses on managing symptoms and reducing glycine levels. This may include dietary modifications, such as restricted protein intake, and medications like sodium benzoate to promote glycine excretion. Supportive care, including seizure management and respiratory support, is often necessary.

Prognosis and Follow-Up

Prognosis is generally poor, with most affected individuals experiencing significant neurological impairment. Long-term follow-up involves regular monitoring of glycine levels, developmental progress, and seizure control. Multidisciplinary care, including neurology and nutrition, is typically required.

Complications

• Severe neurological damage, including intellectual disability.
• Respiratory failure or apnea.
• Feeding difficulties requiring nutritional support.
• Increased risk of infections due to compromised health.

Lifestyle & Prevention

• Genetic counseling for families with a history of the disorder.
• Prenatal testing or carrier screening for at-risk pregnancies.
• Adherence to prescribed dietary and medical treatments to manage symptoms.

When to Seek Professional Help

Seek immediate medical attention if symptoms such as seizures, lethargy, or respiratory distress occur, as these may indicate a medical emergency. Regular follow-up with a healthcare provider is recommended for ongoing management.

Tips for Medical Coders

Document the diagnosis of non-ketotic hyperglycinemia using ICD-10 code E72.51. Ensure clinical documentation supports the diagnosis, including laboratory findings (elevated glycine levels) and genetic testing results when available. Note any associated complications or treatments to support accurate coding.