Systemic Primary Carnitine Deficiency (SPCD) is a rare genetic disorder that affects the body's ability to transport long-chain fatty acids into the mitochondria for energy production. It is caused by mutations in the SLC22A5 gene, which encodes the protein responsible for transporting carnitine into cells.
Diagnosing SPCD involves a combination of clinical evaluation, biochemical testing, and genetic analysis. The initial step is to assess the patient's medical history and symptoms. Individuals with SPCD typically present with symptoms such as muscle weakness, low blood sugar, and cardiomyopathy.
Biochemical testing plays a crucial role in diagnosing SPCD. The most common test is the measurement of plasma carnitine levels. Individuals with SPCD have significantly reduced levels of carnitine in their blood. A low free carnitine level, along with an elevated acylcarnitine profile, can indicate SPCD. This profile is obtained through tandem mass spectrometry, which measures the different forms of acylcarnitines in the blood.
Genetic analysis is the definitive method for diagnosing SPCD. It involves sequencing the SLC22A5 gene to identify any mutations. This analysis can be performed using various techniques, including Sanger sequencing or next-generation sequencing. Identifying mutations in the SLC22A5 gene confirms the diagnosis of SPCD.
It is important to note that SPCD can present with a wide range of symptoms and severity, making diagnosis challenging. Therefore, it is crucial to consider SPCD in individuals with unexplained muscle weakness, cardiomyopathy, or low blood sugar, especially in infants and children.
Early diagnosis of SPCD is essential for initiating appropriate treatment, which typically involves lifelong carnitine supplementation. Carnitine supplementation helps restore normal carnitine levels and improves symptoms in individuals with SPCD.