Our clinical reasoning paper describes a unique case of the rare neonatal form of CPT2 deficiency. Our patient developed acute clinical decompensation on day two of life followed by encephalopathy, hypotonia, and weakness. Our manuscript guides the reader through a discussion of the differential diagnosis for sudden decompensation in a previously healthy neonate, and provides a framework to aid the diagnostic evaluation. The data deposited here summarizes detailed serologic, electroencephalographic, radiologic, and genetic studies that supported the diagnosis of CPT2 deficiency.

Supplementary Figure 1: Normalized Electroencephalographic Data and Family Pedigree.

(A) Follow-up amplitude integrated EEG at 24 hours demonstrated improved continuity and increased peak amplitudes. Similar to continuous EEG, amplitude integrated EEG provides information on voltage amplitude, background continuity, presence of sleep-wake cycles, and can aid in the prognostication of neonates with encephalopathy. (B) Repeat continuous EEG at 24 hours shows reduced discontinuity and improved variability and reactivity; no epileptiform discharges are present. (C) Family pedigree. The arrowhead indicates the proband and the red square indicates CPT2 deficiency. Of note, the mother’s pregnancy history was significant for two first-trimester spontaneous abortions of unknown etiology, as well as an infant born at 26 weeks who passed away within 24 hours of delivery from pulmonary complications of prematurity in a low-resource setting.

Supplementary Table 1: Comprehensive laboratory results from the patient's diagnostic evaluation.

For tests that were repeated during hospitalization, only the first test result is presented in the table. Abnormal values are in bold font.