Primary Carnitine Deficiency (SLC22A5)
Primary carnitine deficiency is an autosomal recessive disorder caused by pathogenic variants in the gene SLC22A5. While the disease is diagnosed in populations worldwide, there is a high prevalence in individuals from the Faroe Islands. There are several different presentations of the disease that vary in their severity. In the most severe form, infants experience recurrent bouts of low blood sugar, which causes lethargy, irritability and poor feeding. If not treated, infants may fall into a coma and die. The milder form is diagnosed in children between the ages of 2 and 4 and presents with muscle weakness and dilated cardiomyopathy. If not treated, the cardiomyopathy may be fatal. Sometimes, adults with muscle fatigue are diagnosed with a very mild form, and some individuals have been found to be asymptomatic. Early diagnosis and modern treatments can allow most patients to have normal life spans. Generally, null variants are associated with more severe disease, but it is not always possible to predict the phenotype based on the patients genotype.
For information about carrier frequency and residual risk, please see the residual risk table.