RETROSPECTIVE BIOCHEMICAL SCREENING OF FATTY-ACID OXIDATION DISORDERSIN POSTMORTEM LIVERS OF 418 CASES OF SUDDEN-DEATH IN THE FIRST-YEAR OF LIFE

Objective: Fatty acid oxidation (FAO) disorders are frequently reporte d as the cause of sudden and unexpected death, but their postmortem re cognition remains difficult. We have devised a biochemical protocol in which informative findings in liver tissue are microvesicular steatos is, elevated concentrations of C-8-C-16 fatty acids, glucose depletion , and low carnitine concentration. Study design: We analyzed 27 cases representing five FAO disorders and compared the results with those ob tained in a retrospective blinded analysis of 418 cases of sudden infa nt death (313 SIDS, 45 infections, and 34 accidents and abuse). Result s: All cases of accidents and abuse correctly tested negative. Among t he others, 25 (6%) showed at least two abnormal findings. Of these, 14 closely matched the biochemical profiles seen in specific FAO disorde rs. These included 2 cases with medium-chain acyl-CoA dehydrogenase de ficiency, 4 cases consistent with glutaric acidemia type 2, 4 cases wi th either very long-chain acyl-coenzyme A dehydrogenase deficiency or long-chain 3-hydroxy-acyl-coenzyme A dehydrogenase deficiency, and 4 c ases predicted to be affected with carnitine uptake defect. Conclusion : The results of this study support the view that approximately 5% of all cases of sudden infant death are likely caused by an FAO disorder.