Cardiac conduction improvement in two heterozygotes for primary carnitine deficiency on L-carnitine supplementation

Area of Science:

• Biochemistry
• Genetics
• Metabolic Disorders

Background:

• Expanded newborn screening (NBS) for free carnitine identifies infants with primary carnitine deficiency (PCD).
• This screening also reveals heterozygous family members, including mothers, who may be undiagnosed.
• Heterozygous carriers of fatty acid oxidation (FAO) gene mutations can develop symptoms under stress.

Observation:

• A family spanning three generations was studied.
• An infant identified via NBS led to the diagnosis of her mother and grandparents.
• The mother and grandparents were asymptomatic or had cardiac symptoms.

Findings:

• The study identified an asymptomatic infant with PCD, her asymptomatic PCD-affected mother, and heterozygous maternal grandparents.
• The maternal grandparents reported cardiac symptoms that improved with L-carnitine supplementation.
• This highlights the phenotypic variability and potential benefits of L-carnitine in PCD heterozygotes.

Implications:

• NBS for carnitine is crucial for identifying not only affected infants but also at-risk heterozygous family members.
• Understanding the lifelong clinical course and biochemical parameters of PCD heterozygotes is important.
• Early identification and potential treatment with L-carnitine may prevent or alleviate symptoms in susceptible individuals.