A neonatal patient died suddenly due to a rare form of long chain fatty acid oxidation disorder (LCFAOD) called carnitine-acylcarnitine translocase deficiency (CACTD), according to a recent case report published in Legal Medicine.

They found that the patient had a compound mutation in the SLC25A20 gene leading to disruption of the carnitine cycle and mitochondrial fatty acid β-oxidation (FAO).

The patient displayed a series of severe metabolic crises before deteriorating rapidly and dying 3 days after delivery.

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“Pathological changes such as heart failure, arrhythmia and cardiac arrest related to mitochondrial FAO disorders are the direct cause of death, while gene mutation is the underlying cause of death,” the authors said.

The researchers found that the infant had a compound heterozygote mutation with c.199–10 T > G and a novel c.1A > T mutation in the SLC25A20 gene. The parents were found to be carriers of the 2 mutations as well.

Read more about LCFAOD symptoms

The patient was hospitalized 2 days after birth and presented with hypnesthesia, convulsions, hypothermia, and bradypnea. The baby also had reduced body temperature, blood pressure, and low oxygen percentage on physical examination.

Blood work revealed hypoglycemia, hyperammonemia, and increased levels of lactate dehydrogenase. Further lab work revealed an increase in several enzymes including alanine transaminase, transglutaminase, aspartate transaminase, creatine kinase, and creatine kinase-MB. Dried blood spot analysis revealed increased levels of C12-C18 acylcarnitine indicating an LCFAOD.

On autopsy, it was found that the infant had patent foramen ovale and 4 lobes on the right lung. Histology revealed extensive vacuolar degeneration in cardiac tissue and a high amount of diffuse vacuoles in hepatocytes.

“CACTD is often asymptomatic or with only some nonspecific symptoms, and therefore it is likely to be misdiagnosed and lead to medical disputes due to unexpected sudden death,” the authors said.

“Due to the disorders of mitochondrial FAO, steatosis and lipid storage in the heart and liver could be found during autopsy and histopathological observation. However, gene mutation detection is the gold standard for diagnosis of CACTD.”


Li X, Zhao F, Zhao Z, et al. Neonatal sudden death caused by a novel heterozygous mutation in SLC25A20 gene: a case report and brief literature review. Leg Med (Tokyo). 2021;54:101990. doi:10.1016/j.legalmed.2021.101990