Further delineation of short-chain enoyl-CoA hydratase deficiency in the Pacific population.

Short-chain enoyl-coA hydratase (SCEH) deficiency due to biallelic pathogenic ECHS1 variants was first reported in 2014 in association with Leigh syndrome (LS) and increased S-(2-carboxypropyl)cysteine excretion. It is potentially treatable with a valine-restricted, high-energy diet and emergency regimen. Recently, Simon et al. described four Samoan children harbouring a hypomorphic allele (c.489G > A, p.Pro163=) associated with reduced levels of normally-spliced mRNA. This synonymous variant, missed on standard genomic testing, is prevalent in the Samoan population (allele frequency 0.17). Patients with LS and one ECHS1 variant were identified in NZ and Australian genomic and clinical databases. ECHS1 sequence data were interrogated for the c.489G > A variant and clinical data were reviewed. Thirteen patients from 10 families were identified; all had Pacific ancestry including Samoan, Maori, Cook Island Maori, and Tokelauan. All developed bilateral globus pallidi lesions, excluding one pre-symptomatic infant. Symptom onset was in early childhood, and was triggered by illness or starvation in 9/13. Four of 13 had exercise-induced dyskinesia, 9/13 optic atrophy and 6/13 nystagmus. Urine S-(2-carboxypropyl)cysteine-carnitine and other SCEH-related metabolites were normal or mildly increased. Functional studies demonstrated skipping of exon four and markedly reduced ECHS1 protein. These data provide further support for the pathogenicity of this ECHS1 variant which is also prevalent in Maori, Cook Island Maori, and Tongan populations (allele frequency 0.14-0.24). It highlights the need to search for a second variant in apparent heterozygotes with an appropriate phenotype, and has implications for genetic counselling in family members who are heterozygous for the more severe ECHS1 alleles. SYNOPSIS: Short-chain enoyl-CoA hydratase deficiency is a frequent cause of Leigh-like disease in Maori and wider-Pacific populations, due to the high carrier frequency of a hypomorphic ECHS1 variant c.489G > A, p.[Pro163=, Phe139Valfs*65] that may be overlooked by standard genomic testing.

The Utility and Diagnostic Accuracy of Transient Elastography in Adults with Morbid Obesity: A Prospective Study.

Patients with morbid obesity are at high risk for nonalcoholic fatty liver disease (NAFLD) complicated by liver fibrosis. The clinical utility of transient elastography (TE) by Fibroscan in patients with morbid obesity (body mass index (BMI) ≥ 40 kg/m2) is not well-defined. We examined the diagnostic accuracy of Fibroscan in predicting significant liver fibrosis (fibrosis stage ≥2) in morbidly obese patients (BMI ≥ 40 kg/m2). Patients scheduled for bariatric surgery were prospectively enrolled. Intraoperative liver biopsy, liver-stiffness measurement (LSM) by Fibroscan (XL probe), and biochemical evaluation were all performed on the same day. The endpoint was significant liver fibrosis defined as fibrosis stage ≥2 based on the Nonalcoholic Steatohepatitis Clinical Research Network. The optimal LSM cutoff value for detecting significant fibrosis was determined by using the Youden Index method. Routine clinical, laboratory, and elastography data were analyzed by stepwise logistic regression analysis to identify predictors of significant liver fibrosis and build a predictive model. An optimal cutoff point of the new model's regression formula for predicting significant fibrosis was determined by using the Youden index method. One hundred sixty-seven patients (mean age, 46.4 years) were included, of whom 83.2% were female. Histological assessment revealed the prevalence of steatohepatitis and significant fibrosis of 40.7% and 11.4%, respectively. The median LSM was found to be significantly higher in the significant fibrosis group compared to those in the no or non-significant fibrosis group (18.2 vs. 7.7 kPa, respectively; p = 0.0004). The optimal LSM cutoff for predicting significant fibrosis was 12.8 kPa, with an accuracy of 71.3%, sensitivity of 73.7%, specificity of 70.9%, positive predictive value of 24.6%, negative predictive value of 95.5%, and ROC area of 0.723 (95% CI: 0.62-0.83). Logistic regression analysis identified three independent predictors of significant fibrosis: LSM, hemoglobin A1c, and alkaline phosphatase. A risk score was developed by using these three variables. At an optimal cutoff value of the regression formula, the risk score had an accuracy of 79.6% for predicting significant fibrosis, sensitivity of 89.5%, specificity of 78.4%, positive predictive value of 34.7%, negative predictive value of 98.3%, and ROC area of 0.855 (95% CI: 0.76-0.95). Fibroscan utility in predicting significant liver fibrosis in morbidly obese subjects is limited with accuracy of 71.3%. A model incorporating hemoglobin A1c and alkaline phosphatase with LSM improves accuracy in detecting significant fibrosis in this patient population.

Compromised hepatic mitochondrial fatty acid oxidation and reduced markers of mitochondrial turnover in human NAFLD.

BACKGROUND AND AIMS: NAFLD and its more-advanced form, steatohepatitis (NASH), is associated with obesity and is an independent risk factor for cardiovascular, liver-related, and all-cause mortality. Available human data examining hepatic mitochondrial fatty acid oxidation (FAO) and hepatic mitochondrial turnover in NAFLD and NASH are scant. APPROACH AND RESULTS: To investigate this relationship, liver biopsies were obtained from patients with obesity undergoing bariatric surgery and data clustered into four groups based on hepatic histopathological classification: Control (CTRL; no disease); NAFL (steatosis only); Borderline-NASH (steatosis with lobular inflammation or hepatocellular ballooning); and Definite-NASH (D-NASH; steatosis, lobular inflammation, and hepatocellular ballooning). Hepatic mitochondrial complete FAO to CO2 and the rate-limiting enzyme in ß-oxidation (ß-hydroxyacyl-CoA dehydrogenase activity) were reduced by ~40%-50% with D-NASH compared with CTRL. This corresponded with increased hepatic mitochondrial reactive oxygen species production, as well as dramatic reductions in markers of mitochondrial biogenesis, autophagy, mitophagy, fission, and fusion in NAFL and NASH. CONCLUSIONS: These findings suggest that compromised hepatic FAO and mitochondrial turnover are intimately linked to increasing NAFLD severity in patients with obesity.

A Model Incorporating Serum Alkaline Phosphatase for Prediction of Liver Fibrosis in Adults with Obesity and Nonalcoholic Fatty Liver Disease.

We assessed the relationship between serum alkaline phosphatase (ALP) and liver fibrosis by histology, in addition to other noninvasive parameters, in obese patients undergoing metabolic surgery. Patients scheduled for elective bariatric surgery were prospectively recruited from a bariatric clinic. An intraoperative liver biopsy was performed, and liver histology was evaluated by a pathologist blinded to the patients' data. The endpoint was significant fibrosis defined as fibrosis stage ≥ 2. Independent predictors of fibrosis were identified by logistic regression. Two hundred ten patients were recruited. Liver histology revealed steatosis in 87.1%, steatohepatitis in 21.9%, and significant fibrosis in 10%. Independent predictors of significant fibrosis were ALP (Odds Ratio (OR) 1.03; 95% Confidence interval (CI), 1.01-1.05), alanine aminotransferase (OR 1.02; 95% CI, 1.01-1.03), HbA1c (OR 1.58; 95% CI, 1.20-2.09), and body mass index (OR 1.06; 95% CI, 1.00-1.13). A tree-based model was developed to predict significant fibrosis, with a receiver operating characteristic (ROC) area of 0.845, sensitivity of 0.857, specificity of 0.836, and accuracy of 0.931. The applicability of serum ALP as an independent biomarker of liver fibrosis should be considered in obesity surgery patients, and in the broader context of obese patients with nonalcoholic fatty liver disease.

Dig deeper when it does not make sense: Juvenile xanthomas due to sitosterolemia.

Sitosterolemia is an extremely rare autosomal recessive disease caused by mutations in either ABCG5 or ABCG8, which encode for a sterol efflux transporter (sterolin) that pumps sterols out into the intestinal lumen or into bile. This leads to progressive accumulation of plant sterols in blood and tissues. Clinical presentation is variable and may include xanthoma, arthritis, thyroid dysfunction, premature atherosclerotic disease, splenomegaly, and hematologic manifestations. We report a child presented with multiple xanthomas at age 5.5 years, located on the elbow, knee, and toe. Juvenile xanthogranuloma was considered based on histopathologic findings. At 8 years of age, a lipid profile showed markedly elevated total cholesterol (9.4 mmol/L) and low-density lipoprotein cholesterol (LDL-C, 7.4 mmol/L). Simvastatin therapy was initiated, however, the lipid profile was persistently abnormal. At age 8.5 years, genetic testing identified two novel variants: (NM_022437.3[ABCG8]:c.1444del;p.Leu482Trpfs*40) and (NM_022437.3[ABCG8]:c.1640T>C;p.Leu547Pro) in the ABCG8 gene. Plasma sitosterol was subsequently found to be very high, confirming the diagnosis. She was started on a low plant sterol and cholesterol diet for 6 weeks with insignificant response and therefore ezetimibe (10 mg daily) was added. This resulted in significant reduction of cholesterol, LDL, sitosterol levels, and no further increase in the size of the xanthomas. This case emphasizes the diagnostic odyssey, the benefits of genomic testing and importance of a correct diagnosis in order to initiate appropriate therapy. It also illustrates the importance of considering rare conditions, such as sitosterolemia, as a differential diagnosis in patients with hypercholesterolemia and increased LDL-C.

Age, Sex, and Depot-Specific Differences in Adipose-Tissue Estrogen Receptors in Individuals with Obesity.

OBJECTIVE: The aim of this study was to examine the effects of sex and menopausal status on depot-specific estrogen signaling in white adipose tissue (AT) in age-matched men and women with morbid obesity. METHODS: A total of 28 premenopausal women, 16 postmenopausal women, and 27 age-matched men undergoing bariatric surgery were compared for omental (OM) AT (OMAT) and abdominal subcutaneous (SQ) AT (SQAT) genes and proteins. RESULTS: With the exception of fasting nonesterified fatty acids being higher in women (P < 0.01), no differences were found in other indicators of glucose and lipid metabolism. In OMAT, estrogen receptor (ER) beta (ERß) levels were higher in older women than in younger women and older men (sex-age interaction, P < 0.01), and aromatase expression was higher in older men than in older women (P < 0.05). In SQAT, women had lower expression of ERß than men (P < 0.05). Protein content of ER alpha and ERß was highly correlated with the mitochondrial protein uncoupling protein 1 across sexes and ages (P < 0.001). Age increased SQ inflammatory gene expression in both sexes. CONCLUSIONS: In morbid obesity, sex and age affect AT ERs, lipid metabolism, mitochondrial uncoupling protein 1, and inflammatory expression in an AT depot-dependent manner. The SQAT immunometabolic profile is heavily influenced by age and menopause status, more so than OMAT.

Rare presentation of De Garengeot hernia in a 77-year-old woman.

A 77-year-old woman presented with a rare surgical phenomenon known as De Garengeot hernia. This unique presentation occurs due to the presence of a vermiform appendix in a femoral hernia sac. The patient presented with right-sided groin pain and a partially reducible hernia; she was otherwise haemodynamically stable and denied fevers, nausea and vomiting. The diagnosis was confirmed with CT which demonstrated a right-sided femoral hernia containing a perforated tip of the appendix. The patient urgently underwent an open appendectomy and open right femoral hernia repair using the modified McEvedy's incision.

A Systematic Review and Meta-Analysis of Single-Incision Versus Multiport Laparoscopic Complete Mesocolic Excision Colectomy for Colon Cancer.

Background. Our aim was to compare the emerging technique of single-incision laparoscopic surgery complete mesocolic excision (SILS CME) colectomy with the standard multiport laparoscopic CME (MPL CME) colectomy. Methods. MEDLINE (PubMed), Scopus, EMBASE, Ovid, and the Cochrane library were searched. Studies comparing the SILS CME with MPL CME in adults with colon adenocarcinoma were included. The Jadad and Newcastle Ottawa Scales were used to critically appraise the studies. The presence of statistical heterogeneity or publication bias was examined. Results. Seven studies (3 randomized) with a total number of 1344 patients were included (546 SILS CME and 798 MPL CME). No difference was found in anastomotic leakage (odds ratio [OR] = 0.79 [0.31 to 2.03]; P = .63), number of lymph nodes (weighted mean difference [WMD] = 0.85 [-0.97 to 2.66]; P = .36), hospital stay (WMD = 0.01 [-0.19 to 0.20]; P = .96), overall survival (hazard ratio [HR] = 1.19 [0.29 to 4.80]; P = .81), and disease-free survival (HR = 1.30 [0.30 to 5.61]; P = .72). Skin incision was shorter in SILS CME group (WMD = -3.02 [-3.25 to -2.80]; P < .00001) but with no difference in pain reported in postoperative day 1 (standardized mean difference [SMD] = -0.21 [-0.50 to 0.09]; P = .17) or day 2 (SMD = 0.16 [-0.52 to 0.84]; P = .64). Conclusions. SILS CME, although technically more demanding, has equivalent short- and long-term outcomes when compared with MPL CME. Potential benefits in cosmesis or postoperative pain need to be further explored by high-quality randomized controlled trials.

Clinical, biochemical and metabolic characterisation of a mild form of human short-chain enoyl-CoA hydratase deficiency: significance of increased N-acetyl-S-(2-carboxypropyl)cysteine excretion.

BACKGROUND: Short-chain enoyl-CoA hydratase-ECHS1-catalyses many metabolic pathways, including mitochondrial short-chain fatty acid ß-oxidation and branched-chain amino acid catabolic pathways; however, the metabolic products essential for the diagnosis of ECHS1 deficiency have not yet been determined. The objective of this report is to characterise ECHS1 and a mild form of its deficiency biochemically, and to determine the candidate metabolic product that can be efficiently used for neonatal diagnosis. METHODS: We conducted a detailed clinical, molecular genetics, biochemical and metabolic analysis of sibling patients with ECHS1 deficiency. Moreover, we purified human ECHS1, and determined the substrate specificity of ECHS1 for five substrates via different metabolic pathways. RESULTS: Human ECHS1 catalyses the hydration of five substrates via different metabolic pathways, with the highest specificity for crotonyl-CoA and the lowest specificity for tiglyl-CoA. The patients had relatively high (∼7%) residual ECHS1 enzyme activity for crotonyl-CoA and methacrylyl-CoA caused by the compound heterozygous mutations (c.176A>G, (p.N59S) and c.413C>T, (p.A138V)) with normal mitochondrial complex I-IV activities. Affected patients excrete large amounts of N-acetyl-S-(2-carboxypropyl)cysteine, a metabolite of methacrylyl-CoA. CONCLUSIONS: Laboratory data and clinical features demonstrated that the patients have a mild form of ECHS1 deficiency harbouring defective valine catabolic and ß-oxidation pathways. N-Acetyl-S-(2-carboxypropyl) cysteine level was markedly high in the urine of the patients, and therefore, N-acetyl-S-(2-carboxypropyl)cysteine was regarded as a candidate metabolite for the diagnosis of ECHS1 deficiency. This metabolite is not part of current routine metabolic screening protocols, and its inclusion, therefore, holds immense potential in accurate diagnosis.

Metabolite studies in HIBCH and ECHS1 defects: Implications for screening.

3-Hydroxyisobutyryl-CoA hydrolase deficiency (HIBCHD) is a rare inborn error of the valine catabolic pathway associated with Leigh-like disease. We report a female patient who presented at the age of 5months with hypotonia, developmental delay and cerebral atrophy on MRI. Pyruvate dehydrogenase deficiency was initially suspected and decreased activity was shown in fibroblasts. Urine tandem mass spectrometry screening showed large increases in the cysteine conjugate of methacrylate previously described in HIBCHD. 3-hydroxyisobutyryl-CoA hydrolase activity in fibroblasts was below the limit of detection of the enzymatic assay and two novel HIBCH mutations were identified (c.[129dupA];[1033G>A]). Urine metabolite investigations also showed increases in 3-hydroxyisobutyryl carnitine, 2,3-dihydroxy-2-methylbutyrate and several metabolites indicating accumulation and subsequent metabolism of methacrylyl-CoA and acryloyl-CoA. The metabolites derived from acryloyl-CoA were also increased in patients with inborn errors of propionyl-CoA metabolism, indicating the involvement of a secondary propionyl-CoA pathway utilising 3-hydroxyisobutyryl-CoA hydrolase. With the exception of 3-hydroxyisobutyryl carnitine, the metabolite abnormalities were essentially the same as those observed in patients with ECHS1 mutations, a recently described disorder that also affects valine metabolism. Our findings demonstrate the benefits of urine tandem mass spectrometry screening for diagnosing HIBCH and ECHS1 defects and that propionate metabolism may play a role in their pathogenesis. These disorders should be considered during the differential diagnosis of Leigh like-diseases and hypotonia.

ECHS1 mutations in Leigh disease: a new inborn error of metabolism affecting valine metabolism.

Two siblings with fatal Leigh disease had increased excretion of S-(2-carboxypropyl)cysteine and several other metabolites that are features of 3-hydroxyisobutyryl-CoA hydrolase (HIBCH) deficiency, a rare defect in the valine catabolic pathway associated with Leigh-like disease. However, this diagnosis was excluded by HIBCH sequencing and normal enzyme activity. In contrast to HIBCH deficiency, the excretion of 3-hydroxyisobutyryl-carnitine was normal in the children, suggesting deficiency of short-chain enoyl-CoA hydratase (ECHS1 gene). This mitochondrial enzyme is active in several metabolic pathways involving fatty acids and amino acids, including valine, and is immediately upstream of HIBCH in the valine pathway. Both children were compound heterozygous for a c.473C > A (p.A158D) missense mutation and a c.414+3G>C splicing mutation in ECHS1. ECHS1 activity was markedly decreased in cultured fibroblasts from both siblings, ECHS1 protein was undetectable by immunoblot analysis and transfection of patient cells with wild-type ECHS1 rescued ECHS1 activity. The highly reactive metabolites methacrylyl-CoA and acryloyl-CoA accumulate in deficiencies of both ECHS1 and HIBCH and are probably responsible for the brain pathology in both disorders. Deficiency of ECHS1 or HIBCH should be considered in children with Leigh disease. Urine metabolite testing can detect and distinguish between these two disorders.

Early diagnosis of adenylosuccinate lyase deficiency using a high-throughput screening method and a trial of oral S-adenosyl-l-methionine as a treatment method.

AIM: The aim of this study was to develop a high-throughput urine screening technique for adenylosuccinate lyase (ADSL) deficiency and to evaluate S-adenosyl-l-methionine (SAMe) as a potential treatment for this disorder. METHOD: Testing for succinyladenosine (S-Ado), a marker of ADSL deficiency, was incorporated into a screening panel for urine biomarkers for inborn errors of metabolism using electrospray tandem mass spectrometry. Liquid chromatography-mass spectrometry and high-performance liquid chromatography were used to confirm and monitor the response of metabolites to oral SAMe treatment. RESULTS: Increased levels of S-Ado were detected in a 3-month-old male infant with hypotonia and seizures. ADSL gene sequencing revealed a previously described c.-49T>C mutation and a novel c.889_891dupAAT mutation, which was likely to disrupt enzyme function. After 9 months of SAMe treatment, there was no clear response evidenced in urine metabolite levels or clinical parameters. INTERPRETATION: These results demonstrate proof of the principle for the high-throughput urine screening technique, allowing earlier diagnosis of patients with ADSL deficiency. However, early treatment with SAMe does not appear to be effective in ADSL deficiency. It is suggested that although SAMe treatment may ameliorate purine nucleotide deficiency, it cannot correct metabolic syndromes in which a toxic nucleotide is present, in this case presumed to be succinylaminoimidazole carboxamide ribotide.

Fetal progenitor cell transplantation treats methylmalonic aciduria in a mouse model.

Methylmalonic aciduria is a rare disorder caused by an inborn error of organic acid metabolism. Current treatment options are limited and generally focus on disease management. We aimed to investigate the use of fetal progenitor cells to treat this disorder using a mouse model with an intermediate form of methylmalonic aciduria. Fetal liver cells were isolated from healthy fetuses at embryonic day 15-17 and intravenously transplanted into sub-lethally irradiated mice. Liver donor cell engraftment was determined by PCR. Disease correction was monitored by urine and blood methylmalonic acid concentration and weight change. Initial studies indicated that pre-transplantation sub-lethal irradiation followed by transplantation with 5 million cells were suitable. We found that a double dose of 5 million cells (1 week apart) provided a more effective treatment. Donor cell liver engraftment of up to 5% was measured. Disease correction, as defined by a decrease in blood methylmalonic acid concentration, was effected in methylmalonic acid mice transplanted with a double dose of cells and who showed donor cell liver engraftment. Mean plasma methylmalonic acid concentration decreased from 810 ± 156 (sham transplanted) to 338 ± 157 µmol/L (double dose of 5 million cells) while mean blood C3 carnitine concentration decreased from 20.5 ± 4 (sham transplanted) to 5.3 ± 1.9 µmol/L (double dose of 5 million cells). In conclusion, higher levels of engraftment may be required for greater disease correction; however these studies show promising results for cell transplantation biochemical correction of a metabolic disorder.

Tissue-specific splicing of an Ndufs6 gene-trap insertion generates a mitochondrial complex I deficiency-specific cardiomyopathy.

Mitochondrial complex I (CI) deficiency is the most common mitochondrial enzyme defect in humans. Treatment of mitochondrial disorders is currently inadequate, emphasizing the need for experimental models. In humans, mutations in the NDUFS6 gene, encoding a CI subunit, cause severe CI deficiency and neonatal death. In this study, we generated a CI-deficient mouse model by knockdown of the Ndufs6 gene using a gene-trap embryonic stem cell line. Ndufs6(gt/gt) mice have essentially complete knockout of the Ndufs6 subunit in heart, resulting in marked CI deficiency. Small amounts of wild-type Ndufs6 mRNA are present in other tissues, apparently due to tissue-specific mRNA splicing, resulting in milder CI defects. Ndufs6(gt/gt) mice are born healthy, attain normal weight and maturity, and are fertile. However, after 4 mo in males and 8 mo in females, Ndufs6(gt/gt) mice are at increased risk of cardiac failure and death. Before overt heart failure, Ndufs6(gt/gt) hearts show decreased ATP synthesis, accumulation of hydroxyacylcarnitine, but not reactive oxygen species (ROS). Ndufs6(gt/gt) mice develop biventricular enlargement by 1 mo, most pronounced in males, with scattered fibrosis and abnormal mitochondrial but normal myofibrillar ultrastructure. Ndufs6(gt/gt) isolated working heart preparations show markedly reduced left ventricular systolic function, cardiac output, and functional work capacity. This reduced energetic and functional capacity is consistent with a known susceptibility of individuals with mitochondrial cardiomyopathy to metabolic crises precipitated by stresses. This model of CI deficiency will facilitate studies of pathogenesis, modifier genes, and testing of therapeutic approaches.

An in vitro paradigm for diabetic cerebral oedema and its therapy: a critical role for taurine and water channels.

The pathophysiology of cerebral oedema (CE) in diabetic ketoacidosis (DKA) remains enigmatic. We investigated the role of the idiogenic osmol taurine and aquaporin channels in an in vitro model, the SH-SY5Y neuroblastoma cell line, by sequentially mimicking DKA-like hyperglycemia/hypertonicity and hypotonic fluid therapy. Exposure to DKA-like hyperosmolarity led to shrinkage, while hypotonic fluid exposure led to cell swelling and impaired viability. Low sodium compensated in part for elevated glucose, pointing to a critical role for overall osmolality. Taurine, was synthesized and retained intracellularly during DKA-like hypertonicity, and released during hypotonicity, in part mitigating neuronal swelling. Metabolic labeling showed that the rate of taurine release was inadequate to fully prevent neuronal swelling during hypotonic fluid therapy following DKA-like hypertonicity. Under these conditions, Aquaporin4 & 9 channels were respectively down and up-regulated. Our study provides further novel insights into molecular mechanisms contributing to CE in DKA and its therapy.

Newborn screening.

Early detection of many disorders, mainly inherited, is feasible with population-wide analysis of newborn dried blood spot samples. Phenylketonuria was the prototype disorder for newborn screening (NBS) and early dietary treatment has resulted in vastly improved outcomes for this disorder. Testing for primary hypothyroidism and cystic fibrosis (CF) was later added to NBS programs following the development of robust immunoassays and molecular testing. Current CF testing usually relies on a combined immunoreactive trypsin/mutation detection strategy. Multiplex testing for approximately 25 inborn errors of metabolism using tandem mass spectrometry is a relatively recent addition to NBS. The simultaneous introduction of many disorders has caused some re-evaluation of the traditional guidelines for NBS, because very rare disorders or disorders without good treatments can be included with minimal effort. NBS tests for many other disorders have been developed, but these are less uniformly applied or are currently considered developmental. This review focuses on Australasian NBS practices.

Adenylosuccinate lyase deficiency in a Malaysian patient, with novel adenylosuccinate lyase gene mutations.

Most cases of adenylosuccinate lyase (ADSL OMIM 103050) deficiency reported to date are confined to the various European ethnic groups. We report on the first Malaysian case of ADSL deficiency, which appears also to be the first reported Asian case. The case was diagnosed among a cohort of 450 patients with clinical features of psychomotor retardation, global developmental delay, seizures, microcephaly and/or autistic behaviour. The patient presented with frequent convulsions and severe myoclonic jerk within the first few days of life and severe psychomotor retardation. The high performance liquid chromatography (HPLC) profile of the urine revealed the characteristic biochemical markers of succinyladenosine (S-Ado) and succinyl-aminoimidazole carboximide riboside (SAICAr). The urinary S-Ado/SAICAr ratio was found to be 1.02 (type I ADSL deficiency). The patient was compound heterozygous for two novel mutations, c.445C > G (p.R149G) and c.774_778insG (p.A260GfsX24).

Metabolic profiling of infant urine using comprehensive two-dimensional gas chromatography: Application to the diagnosis of organic acidurias and biomarker discovery.

Comprehensive two-dimensional gas chromatography (GCxGC) time-of-flight mass spectrometry (ToFMS) was applied to the analysis of urinary organic acids from patients with inborn errors of metabolism. Abnormal profiles were obtained from all five patients studied. Methylmalonic academia and deficiencies of 3-methylcrotonyl-CoA carboxylase and medium chain acyl-CoA dehydrogenase gave diagnostic profiles while deficiencies of very long chain acyl-CoA dehydrogenase and mitochondrial 3-hydroxy-3-methylglutaryl CoA synthase gave profiles with significant increases in dicarboxylic acids suggestive of these disorders. The superior resolving power of GCxGC with ToFMS detection was useful in separating isomeric organic acids that were not resolved using one-dimensional GC. A novel urinary metabolite, crotonyl glycine, was also discovered in the mitochondrial 3-hydroxy-3-methylglutaryl CoA synthase sample which may be a useful specific diagnostic marker for this disorder. The quantitative aspects of GCxGC were investigated using stable isotope dilution analyses of glutaric, glyceric, orotic, 4-hydroxybutyric acids and 3-methylcrotonylglycine. Correlation coefficients for linear calibrations of the analytes ranged from 0.9805 to 0.9993 (R(2)) and analytical recoveries from 77% to 99%. This study illustrates the potential of GCxGC-ToFMS for the diagnosis of organic acidurias and detailed analysis of the complex profiles that are often associated with these disorders.