A newborn screening approach to diagnose 3‐hydroxy‐3‐methylglutaryl‐CoA lyase deficiency

Abstract

3‐Hydroxy‐3‐methylglutaryl‐coenzyme A lyase deficiency (HMGCLD) is a rare autosomal recessively inherited metabolic disorder. Patients suffer from avoidable neurologically devastating metabolic decompensations and thus would benefit from newborn screening (NBS). The diagnosis is currently made by measuring dry blood spot acylcarnitines (C5OH and C6DC) followed by urinary organic acid profiling for the differential diagnosis from several other disorders. Using untargeted metabolomics (reversed‐phase UHPLC coupled to an Orbitrap Elite hybrid mass spectrometer) of plasma samples from 5 HMGCLD patients and 19 age‐matched controls, we found 3‐methylglutaconic acid and 3‐hydroxy‐3‐methylglutaric acid, together with 3‐hydroxyisovalerylcarnitine as the most discriminating metabolites between the groups. In order to evaluate the NBS potential of these metabolites we quantified the most discriminating metabolites from untargeted metabolomics in 23 blood spots from 4 HMGCLD patients and 55 controls by UHPLC tandem mass spectrometry. The results provide a tool for expanded NBS of HMGCLD using tandem mass spectrometry. Selected reaction monitoring transition 262/85 could be used in a first‐tier NBS analysis to screen for elevated 3‐hydroxyisovalerylcarnitine. In a positive case, a second‐tier analysis of 3‐hydroxy‐3‐methylglutaric acid and 3‐methylglutaconic acid in a dry blood spot using UHPLC tandem mass spectrometry instruments confirms the diagnosis. In conclusion, we describe the identification of new diagnostic biomarkers for HMGCLD and their application in NBS in dry blood spots. By using second‐tier testing, all patients with HMGCLD were unequivocally and correctly diagnosed.

Diagnosis of inborn errors of metabolism within the expanded newborn screening in the Madrid region

“…Detection of HMG-CoA lyase deficiency is essential as about half of the patients become symptomatic within the neonatal period. 50 The death rate in our population was 1.3% (3/222), a bit lower than observed in other series. 17,51 Early mortality data for PA, LCHADD and OTC was 17, 50, and 50%, respectively.…”

“…For this condition, novel biomarkers have recently been identified 49 ; organic acid analysis in urine is necessary as the second tier‐test for confirmation of this disease. Detection of HMG‐CoA lyase deficiency is essential as about half of the patients become symptomatic within the neonatal period 50 …”

HMG-CoA Lyase Deficiency: A Retrospective Study of 62 Saudi Patients

“…The clinical presentation of HGMCLD is highly heterogeneous but it is usually evident in the neonatal and first year of life. Most affected individuals in our study became symptomatic within the first year after birth (Grunert et al, 2017;Václavík et al, 2020;Grünert and Sass, 2020). HMGCLD patients typically present features such as acute metabolic decompensation that may be life-threatening (Grünert and Sass, 2020).…”

“…This gene is located in the short arm of chromosome 1p36.11 (Pié et al, 2007;Menao et al, 2009), which encodes the enzyme 3-hydroxymethyl-3-methylglutaryl-coenzyme A lyase (HMG-CoA lyase). This mitochondrial enzyme has a role in dietary protein metabolism, which forms acetyl-CoA and acetoacetate from HMG-CoA, known as the final step of leucine degradation and fat breakdown for energy (Puisac et al, 2010;Václavík et al, 2020) (Figure 1). Therefore, the body cannot synthesize ketone bodies, which are essential for energy production during the fasting period (Václavík et al, 2020).…”

“…This mitochondrial enzyme has a role in dietary protein metabolism, which forms acetyl-CoA and acetoacetate from HMG-CoA, known as the final step of leucine degradation and fat breakdown for energy (Puisac et al, 2010;Václavík et al, 2020) (Figure 1). Therefore, the body cannot synthesize ketone bodies, which are essential for energy production during the fasting period (Václavík et al, 2020). The prevalence of this disorder is less than 1/100,000 in live borns (Santarelli et al, 2013), while in Saudi Arabia, the incidence is 1: 55,357 (Alfadhel et al, 2017) which is approximately twice the world incidence.…”