What Is Your Guess? A Four-Day-Old Boy with an Abnormal Metabolic Screen

Abstract

A four-day-old boy with a positive result in newborn-screening testing was referred to the hospital for further evaluation. He was the product of a 39-week gestation and appeared well at birth. His laboratory results included the following plasma findings: ammonia, 109 g/dL (reference interval, 20 -65 g/dL); citrulline, 169 mol/L (reference interval, 2-50 mol/L); and leucine, 278 mol/L (reference interval, 32-153 mol/L). Also found were increases in homocysteine and ␥-aminobutyric acid. The amino acid spectrum is shown below (Fig. 1). QUESTIONS 1. What class of genetic disorders did this patient most likely have? 2. What enzyme deficiency was suggested by the patient's amino acid profile, and how did you reach the conclusion?The answers are on the next page. The patient's plasma sample was analyzed on a Hitachi L-8800 amino acid analyzer after removing proteins by treatment with 40 g/L sulfosalicylic acid/internal standard solution, centrifugation, and filtration. The amino acids were separated by high-resolution ion-exchange chromatography and then subjected to postcolumn ninhydrin derivatization; detection was by spectrophotometry at 570 nm and 440 nm. The areas under the curves were calculated by using the manufacturer's software for final quantification. Hcys, homocysteine; ␥-ABA, ␥-aminobutyric acid; AEC, S-2-aminoethyl-L-cysteine; 3-M Histidine, 3-methylhistidine.

Baseline separation of amino acid biomarkers of hepatocellular carcinoma by polyvinylpyrrolidone-filled capillary electrophoresis with light-emitting diode-induced fluorescence in the presence of mixed micelles

“…Interestingly, up to 2 hours of separation time is required for the examination of AAs by ion-exchange chromatography, which is extensively used in hospitals. 7,44 Therefore, our proposed method still remains a viable option due to the natural superiority of CE. 45,46 Further improvement in the time required for AA analysis could be achieved using pressure-assisted capillary electrophoresis 47 or by shortening the length of separation using chip electrophoresis.…”