ABSTRACT
Medium-chain acyl-CoA dehydrogenase deficiency (MCADD), caused by mutated ACADM gene, is a potentially fatal fatty acid oxidation defect. Detection of MCADD is now part of tandem mass spectrometry (MS-MS)-based newborn screening programs worldwide. To date, more than 67 mutations have been reported to cause MCADD with a single allele, c.985A>G, being the most common in patients of northwestern European descent. In Saudi Arabia, the Newborn Screening Program, officially launched in 2005, screens for 16 disorders including MCADD. Over a period of 3 years, 237,812 newborns were screened; 13 were identified to have MCADD giving an incidence of 1:18,293. Since the introduction of MS-MS to our institution, however, a total of 30 patients were detected to have MCADD. These cases were either newborns, at high-risk family members, or clinically suspected. The C8-carnitine levels (median 3.31, range 0.81-16.33 µM) were clearly diagnostic in all analyzed samples. Sequencing ACADM in 20 DBS revealed two novel mutations: c.362C>T (p.T121I) and c.347G>A (p.C116Y) substitutions, neither of which were detected in 300 chromosomes from controls. Eighteen (90%) patients were homozygous for the T121I mutation and two (10%) were compound heterozygous (T121I/C116Y). Our molecular data lend further support to MS-MS biochemical screening for MCADD and provide evidence for the relatively high incidence of MCADD in the Arab population. The identification of a founder mutation for MCADD has important implications for the preventive screening programs not only in Saudi Arabia but potentially also in other countries in the region.
Subject(s)
Acyl-CoA Dehydrogenase/genetics , Mutation , Acyl-CoA Dehydrogenase/blood , Acyl-CoA Dehydrogenase/deficiency , Biomarkers/blood , Carnitine/blood , DNA Mutational Analysis , Dried Blood Spot Testing , Founder Effect , Gene Frequency , Genetic Predisposition to Disease , Genetic Testing/methods , Humans , Incidence , Infant, Newborn , Lipid Metabolism, Inborn Errors/blood , Lipid Metabolism, Inborn Errors/diagnosis , Lipid Metabolism, Inborn Errors/enzymology , Lipid Metabolism, Inborn Errors/epidemiology , Lipid Metabolism, Inborn Errors/genetics , Lipid Metabolism, Inborn Errors/prevention & control , Neonatal Screening/methods , Phenotype , Predictive Value of Tests , Saudi Arabia/epidemiology , Tandem Mass SpectrometryABSTRACT
Speech parameters may include perturbation measurements, spectral and cepstral modeling, and pathological effects of some diseases, like influenza, that affect the vocal tract. The verification task is a very good process to discriminate between different types of voice disorder. This study investigated the modeling of influenza's pathological effects on the speech signals of the Arabic vowels "A" and "O." For feature extraction, linear prediction coding (LPC) of discrete wavelet transform (DWT) subsignals denoted by LPCW was used. k-Nearest neighbor (KNN) and support vector machine (SVM) classifiers were used for classification. To study the pathological effects of influenza on the vowel "A" and vowel "O," power spectral density (PSD) and spectrogram were illustrated, where the PSD of "A" and "O" was repressed as a result of the pathological effects. The obtained results showed that the verification parameters achieved for the vowel "A" were better than those for vowel "O" for both KNN and SVM for an average. The receiver operating characteristic curve was used for interpretation. The modeling by the speech utterances as words was also investigated. We can claim that the speech utterances as words could model the influenza disease with a good quality of the verification parameters with slightly less performance than the vowels "A" as speech utterances. A comparison with state-of-the-art method was made. The best results were achieved by the LPCW method.
Subject(s)
Influenza, Human/diagnosis , Influenza, Human/physiopathology , Language , Signal Processing, Computer-Assisted , Sound Spectrography , Voice Quality , Wavelet Analysis , Algorithms , Area Under Curve , Humans , Male , Phonation , Phonetics , ROC Curve , Saudi Arabia , Speech , Speech Acoustics , Support Vector Machine , Voice , Voice Disorders , Young AdultABSTRACT
We describe an improved diagnostic method for tyrosinemia type 1 based on quantifying succinylacetone in dried blood spots by ultra-performance liquid chromatography tandem mass spectrometry. Succinylacetone extracted from a single 3/16 inch disk of specimen collection paper containing a dried blood spot was derivatized with dansylhydrazine, separated on an Acquity UPLC BEH C(18) column (2.1 x 50 mm, 1.7 microm) and detected by electrospray ionization tandem mass spectrometry. Succinylacetone derivative eluted at 0.6 min with a complete run time of 1 min. Using a 13C4 labeled succinylacetone as an internal standard, the calibration plot was linear up to 100 micromol/L with a detection limit (S/N = 3) of 0.2 micromol/L. Intra-day (n = 13) and inter-day (n = 10) variations were better than 10%. The cutoff level of succinylacetone in dried blood spots from healthy infants obtained by the current method was 0.63 micromol/L (n = 151). In dried blood spots from patients with established tyrosinemia type 1 (n = 11), concentration of succinylacetone was 6.4-30.8 micromol/L.
Subject(s)
Chromatography, High Pressure Liquid/methods , Heptanoates/blood , Spectrometry, Mass, Electrospray Ionization/methods , Tandem Mass Spectrometry/methods , Tyrosinemias/diagnosis , Heptanoates/chemistry , Humans , Linear Models , Tyrosinemias/bloodABSTRACT
Molybdenum cofactor and isolated sulphite oxidase deficiencies are two related rare autosomal recessive diseases characterized by severe neurological abnormalities, dislocated lens and mental retardation. Determination of three biochemical markers S-sulphocysteine (SSC), xanthine (XAN) and hypoxanthine (HXAN) in urine is essential for a definitive diagnosis and identification of the exact defect. We developed a rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the analysis of SSC, XAN and HXAN in urine. The analysis was carried out in the negative-ion selected-reaction monitoring mode. The turnaround time for the assay was 7 min. Linear calibration curves for the three biomarkers were obtained in the range of 12-480 micromol/L. The intra- and inter-day assay variations were <2.5%. Mean recoveries of SSC, XAN and HXAN added to urine at two significantly different concentrations were in the range 94.3-107.3%. At a normal SSC urine excretion value of 3.2 micromol/mmol creatinine, the signal-to-noise ratio was 337:1. This stable isotope dilution LC-MS/MS method is specific, rapid and simple, and provides definitive diagnosis for molybdenum cofactor and isolated sulphite oxidase deficiencies in very small volumes of urine. We have identified seven new cases of isolated sulphite oxidase deficiency from four Saudi families and one Sudanese family.