Primary carnitine deficiency is a rare, inherited condition in which the body cannot move carnitine, a substance that helps cells turn fat into energy, into its cells. It is included on newborn screening because it is easy to treat when found early.
What causes primary carnitine deficiency
The condition is caused by variants in the SLC22A5 gene, which builds the transporter that carries carnitine into cells. Without it, carnitine levels fall and the body struggles to use fat for energy. It is inherited in an autosomal recessive pattern.
How newborn screening detects it
Newborn screening measures carnitine levels in the heel-prick blood spot and flags a low free carnitine level. Because the baby's result can be influenced by the mother's carnitine level, confirmatory testing is used to establish the diagnosis.
How primary carnitine deficiency is treated
Treatment is straightforward and highly effective: lifelong L-carnitine supplementation, taken by mouth. Started early and continued consistently, it prevents the complications of the condition, which can include heart and muscle problems and low blood sugar. Care is guided by a metabolic specialist.
How genetic screening fits in
State newborn screening does an excellent job of catching primary carnitine deficiency. Genetic screening looks at the same picture from the DNA level and, in a single test, can also assess the genes tied to more than 1,000 other clinically actionable childhood conditions, many of which are not on any state panel. Fore Genomics offers an at-home cheek-swab screen, sequenced in CLIA-certified and CAP-accredited labs, with results supported by board-certified genetic counselors. See what we screen for or start screening.
Frequently asked questions
Is primary carnitine deficiency on newborn screening panels?
Yes. It is a core condition on the federal Recommended Uniform Screening Panel and is screened for across U.S. states.
Is the treatment really just carnitine?
In most cases, yes. Daily L-carnitine at the right dose prevents complications, and it is continued for life under a specialist's guidance.
Is it inherited?
Yes. Primary carnitine deficiency is autosomal recessive, so a child inherits an SLC22A5 variant from each parent.
Related guides
Medically reviewed by Fore's Clinical Team. This article is for general educational purposes and is not medical advice. Sources: HRSA Newborn Screening; National Organization for Rare Disorders (NORD).