Outcome in six patients with mitochondrial trifunctional protein disorders identified by newborn screening.

Before the newborn screening era, disorders of the mitochondrial trifunctional protein (TFP) complex including long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) presented with high morbidity and mortality. Data on outcome and prognosis of TFP deficiency disorders since implementation of screening are scarce. We here characterize 6 screened patients with a disorder of the TFP complex (3 of those with LCHADD) with respect to clinical presentation and molecular features. Three of 6 patients were symptomatic prior availability of screening results on days 4-5 of life. Of the three asymptomatic patients recognised by screening, one acutely died at 3months at home during an infection. Two patients remained asymptomatic with preventive measures during follow-up until the age of 3years. One of them had an older sibling with identical genotype born before the screening era, who became symptomatic with 15months. We conclude that newborn screening for disorders of the TFP complex allows identification of asymptomatic cases; however, the acute presentation in 3/6 babies before screening is noteworthy and troublesome. TFP and LCHAD deficiencies remain life-threatening disorders. This is in clear contrast to other defects of long-chain fatty acid oxidation after identification by newborn screening.