Her medical history included primary carnitine deficiency, a rare inherited metabolic disorder that causes cardiomyopathy, which was diagnosed as asymptomatic during her infancy following the death of her infant brother from cardiomyopathy related to the condition.
Primary carnitine deficiency is a rare autosomal recessive disorder with an incidence of one in 120,000, caused by mutations in the SLC22A5 gene, located on chromosome 5q23.3, which encodes OCTN2 [2].
Primary carnitine deficiency is a gene mutation in SLC22A5, an autosomal recessive gene.
Approximately half of the patients of Primary Carnitine Deficiency present around the age of 2 years (range: 3 months--2.5 years) with metabolic decompensation characterized by episodes of hypoketotic hypoglycemia, hyperammonemia and hepatic encephalopathy (poor feeding, irritability, lethargy), triggered by fasting or common illnesses such as upper respiratory tract infections.
This condition might be a result of secondary carnitine deficiency owing to defect in Carnitine Acyl Transferase-I, II or translocase enzyme, instead of primary carnitine deficiency which presents with severe form.
Carnitine uptake into tissues and cells occurs by a saturable sodium-dependent transport mechanism (21), and a failure of its transport mechanism leads to systemic or
primary carnitine deficiency associated with low levels of free and total carnitine in tissues and plasma.
Primary carnitine deficiency due to a failure of carnitine transport in kidney, muscle and fibroblasts.
Expanded newborn screening identifies maternal
primary carnitine deficiency. Mol Genet Metab 2007;90:441-5.
In the case of
primary carnitine deficiency, the only symptom may be heart failure; however, this disorder responds well to carnitine supplementation.
Whereas
primary carnitine deficiency is attributable to mutations in OCTN2 [a carnitine transporter of plasma membranes (3)], several other conditions can cause secondary deficiency (4).
Presumptive positive results were reported as carnitine deficiency attributable to an uptake disorder, as
primary carnitine deficiency, or as secondary carnitine deficiency attributable to a metabolic disorder that causes depletion of carnitine and affects our ability to find abnormal increases of acylcarnitines.