Systemic primary carnitine deficiency

Carnitine structure

Systemic Primary Carnitine Deficiency (SPCD), also known as Carnitine Uptake Defect or Carnitine Transporter Deficiency, is a rare genetic disorder that affects the body's ability to transport carnitine, a substance essential for the oxidation of long-chain fatty acids. This condition leads to a variety of symptoms, primarily affecting the muscles and heart, and can result in serious complications if not treated promptly.

Causes

SPCD is caused by mutations in the SLC22A5 gene, which encodes the organic cation transporter type 2 (OCTN2), responsible for the uptake of carnitine into cells. Without functional OCTN2, carnitine cannot be properly absorbed from the diet or conserved by the kidneys, leading to a systemic deficiency.

Symptoms

Symptoms of SPCD can vary widely among affected individuals but typically include muscle weakness, hypoglycemia (low blood sugar), cardiomyopathy (disease of the heart muscle), and hepatic encephalopathy (brain dysfunction caused by liver disease). Symptoms can appear anytime from infancy to adulthood, with some individuals remaining asymptomatic.

Diagnosis

Diagnosis of SPCD involves a combination of clinical evaluation, biochemical tests showing low plasma carnitine levels, and genetic testing confirming mutations in the SLC22A5 gene. Early diagnosis and treatment are crucial to prevent serious complications.

Treatment

The primary treatment for SPCD is oral L-carnitine supplementation, which can significantly improve symptoms and prevent metabolic crises. Patients may also require dietary modifications and management of symptoms related to complications.

Prognosis

With early diagnosis and appropriate treatment, individuals with SPCD can lead normal, healthy lives. However, untreated SPCD can result in severe metabolic crises, irreversible organ damage, and potentially fatal outcomes.