The long-term outcomes for asymptomatic adults with SPCD is not known, but the discovery of mothers with undiagnosed cardiomyopathy and SPCD has raised the possibility that identification and treatment may prevent adult-onset manifestations. Incidence
Worldwide, SPCD is most common in the Faroe Islands, where at least one out of every 1000 inhabitants of the Faroes have the disorder, according to the Faroese Ministry of Health. Scientists believe that around 10% of the Faroese population are carriers of variants which cause SPCD. These people are not ill, but may have a lower amount of carnitine in their blood than non-carriers. The first Faroese patient was diagnosed with SPCD in 1995, and since then several young people and children in the Faroese Islands have died of cardiac arrest because of SPCD.The addition of SPCD to newborn screening panels has offered insight into the incidence of the disorder around the world. In Taiwan, the incidence of SPCD in newborns was estimated to be approximately 1:67,000, while maternal cases were identified at a higher frequency of approximately 1:33,000. The increased incidence of SPCD in mothers compared to newborns is not completely understood. Estimates of SPCD in Japan have shown a similar incidence of 1:40,000. History
Carnitine deficiency has been extensively studied, although most commonly as a secondary finding to other metabolic conditions. The first case of SPCD was reported in the 1980s, in a child with fasting hypoketotic hypoglycemia that resolved after treatment with carnitine supplementation. Later cases were reported with cardiomyopathy and muscle weakness.
Newborn screening expanded the potential phenotypes associated with SPCD, to include otherwise asymptomatic adults. References
External links

GeneReviews/NCBI/NIH/UW entry on Systemic Primary Carnitine Deficiency