Analysis of ACAT1 gene variants in a patient with β-ketothiolase deficiency / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic etiology of a child suspected for β-ketothiolase deficiency by neonatal screening.@*METHODS@#All coding exons and flanking sequences of the ACAT1 gene were subjected to targeted capture and high-throughput sequencing. Suspected variants were verified by Sanger sequencing and bioinformatic analysis.@*RESULTS@#The child was found to harbor compound heterozygous variants of the ACAT1 gene, namely c.121-3C>G and c.275G>A (p. Gly92Asp). The c.121-3C>G variant was also detected in his father and two sisters, while the c.275G>A (p. Gly92Asp) was a de novo variant. A c.334+ 172C>G (rs12226047) polymorphism was also detected in his mother and two sisters. Sanger sequencing has verified that the c.275G>A (p. Gly92Asp) and c.334+172C>G (rs12226047) variants are located on the same chromosome. Bioinformatics analysis suggested both c.121-3C>G and c.275G>A (p.G92D) variants to be damaging. Based on the American College of Medical Genetics and Genomics standards and guidelines, the c.275G>A variant of the ACAT1 gene was predicted to be pathogenic (PS2+ PM2+ PM3+ PP3+PP4), the c.121-3C>G variant to be likely pathogenic (PM2+ PM3+ PP3+PP4).@*CONCLUSION@#The c.121-3C>G and c.275G>A variants of the ACAT1 gene probably underlay the pathogenesis of the child. Above finding has enriched the variant spectrum of the ACAT1 gene.

Retrospective analysis on clinical data and genetic variations of patients with beta-ketothiolase deficiency / 中华医学遗传学杂志

OBJECTIVE@#To summarize the clinical, biochemical and molecular characteristics of 8 patients with beta-ketothiolase deficiency (BKD).@*METHODS@#Clinical characteristics, biochemical markers detected by tandem mass spectrometry (MS-MS) and gas chromatography-mass spectrometry (GC-MS), and variations of ACAT1 gene of the 8 patients were reviewed.@*RESULTS@#Three patients were diagnosed by newborn screening and were asymptomatic. Five patients showed dyspnea and metabolic acidosis through high risk screening. Blood methylcrotonyl carnitine (C5:1) were 0.43 (0.20-0.89) μmol/L and 3-hydroxyisovaleryl carnitine(C5-OH) were 1.37 (0.98-3.40) μmol/L. Both were significantly higher than those of healthy controls (PG (p.N375S) variant, which accounted for 28.6% of all 14 mutant alleles. Four novel variants, namely c.229delG (p.E77KfsTer10), c.373G>T (p.V125F), c.419T>G (p.L140R) and c.72+1G>A, were discovered. Pathogenicity assessment of two highly conservative missense variants (p.V125F) and (p.L140R) were 0.994 and 1.0 (Scores obtained from PolyPhen2), and PROVEAN scores were -4.652 and -5.399, respectively. c.72+1g>a was suspected (by Human Splicing Finder) to alter the wild type donor motif and most probably affect the splicing.@*CONCLUSION@#Clinicians should consider MS/MS and GC/MS testing for those with unexplained neurological symptoms and metabolic acidosis in order to attain early diagnosis of BKD. Genetic testing should be used to confirm the diagnosis.

Two Libyan siblings with beta-ketothiolase deficiency: a case report and review of literature

Beta-ketothiolase [mitochondrial acetoacetyl-CoA thiolase, T2] deficiency is an autosomal recessive disorder characterized by impaired metabolism of ketones and isoleucine. In this study, we report on the first two siblings with T2 deficiency from Libya. Both siblings presented with ketoacidosis, but the severity and outcomes were quite distinctive. T2 deficiency in patient 1, the younger sister, manifested as recurrent severe episodes of ketoacidosis during the first year of life. She unfortunately experienced neu-rodevelopmental complications, and died at 14 months old, after her 5th episode. In contrast, patient 2, the elder brother, experienced only one ketoacidotic episode at the age of 4 years. He recovered uneventfully and has continued to achieve age-appropriate development to date. Upon analysis, the siblings' blood acylcarnitine profiles had shown increased levels of C5:l and C5-OH carnitine. ACAT1 mutational analysis revealed patient 2 is homozygotic for a novel mutation-c.674C > A [p.Ala225Glu]; this mutation was then confirmed by familial analysis. Transient expression analysis of C.674C > A mutant T2 cDNA revealed neither potassium ion-activated acetoacetyl-CoA thiolase activity, which represents T2 activity, nor mutant T2 protein. Therefore, this mutation is truly pathogenic. Interestingly, the incidence of T2 deficiency may be high among the Arab population. This disease should be considered in the differential diagnosis for unexplained ketoacidosis in children. Patients with T2 deficiency could have a favorable outcome if diagnosed and treated early

Analysis of clinical phenotype and ACAT1 gene mutation in a family affected with beta-ketothiolase deficiency / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the clinical phenotype and ACAT1 gene mutation in a family affected with beta-ketothiolase deficiency (BKTD).</p><p><b>METHODS</b>Clinical features and laboratory test data were collected. The probands were monozygotic twin brothers. Genomic DNA was isolated from peripheral blood leukocytes obtained from the probands and their family members. Molecular genetic testing of the ACAT1 gene was carried out.</p><p><b>RESULTS</b>The probands have presented with fever, vomiting and severe ketoacidosis. By arterial blood gas testing, pH was determined to be 7.164, bicarbonate was 4.0 mmol/L, and urine ketone was ++++. Urinary organic acid gas chromatography-mass spectrometry analysis showed excessive excretion of 3-hydroxybutyric acid, 2-methyl-3-hydroxybutyric acid and tiglylglycine. Increased 3-hydroxybutyrylcarnitine (C4-OH), tiglylcarnitine(C5:1) and 3-hydroxyisovalerylcarnitine (C5-OH) levels. The clinical phenotype of proband's parents were both normal, but an elder sister turned out to be an affected patient. Genetic analysis has identified two heterozygous mutations [c.622C>T(p.R208X) and c.653C>T (p.S218F)] in the proband, which were respectively detected in the mother and father. The c.653C>T (p.S218F) mutation was not found among the 100 healthy controls and has not been included in the Human Gene Mutation Database(HGMD).</p><p><b>CONCLUSION</b>The primary clinical manifestations of BKTD is ketoacidosis. Urine organic acid and blood acylcarnitine analyses play an important role in the diagnosis of the disease. The compound heterozygous of ACAT1 gene mutations probably underlie the BKTD in our patient.</p>

A Case of Partial Trisomy 9p Syndrome with 3-Ketothiolase Deficiency

Trisomy 9p syndrome was first described by Rethore et al in 1970 and about 150 cases have been reported. The characteristic features of the partial trisomy 9p syndrome is clearly recognizable faces, which include microcephaly, facial deformities, skeletal and dermatoglyphic anomalies with variable degrees of mental retardation. The 3-ketothiolase deficiency was first described in 1971 and about 30 cases have been reported. The 3-ketothiolase deficeiency is an inborn error of isoleucine and ketone body catabolism that shows autosomal recessive traits, caused by a deficiency of mitochondrial acetoacetyl-coenzyme A thiolase(T2). We report a case of partial trisomy 9p syndrome with 3-ketothiolase deficeiency in a 4-years-old female. The karyotype of the patient was confirmed as 46,XY, add(9)(p23) mat. In the urine organic acid test, 3-ketothiolase deficiency was reported.

Organic acidemias in Korea: Eight years experience of organic acid analysis / 소아과

PURPOSE: We have done this retrospective study to know the relative incidence and clinical manifestations of organic acidopathies in Korea during 8 years(from Jul. 1997 to May 2005). This results of organic acid analysis of 1,787 patients were compared with the results of organic acid analysis that were published three years ago. METHODS: The results of quantitative organic acid analysis of samples of 1788 patients, referred from Jul. 1997 to May 2005, were analyzed retrospectively according to four age group(-2 mon, 3 mon-2 years, 3-12 years) and major clinical manifestations. Quantification of 83 organic acids was done with gas chromatography and mass spectometry. RESULTS: We diagnosed 470 patients with 27 diseases of organic acid metabolism during this study period. Diseases found more than 10 cases are cytosolic 3-ketothiolase deficiency, mitochondrial respiratory chain disorders, PDHC deficiency, mitochondrial 3-ketothiolase deficiency, glutaric aciduria type II, biotinidase deficiency, methylmalonic aciduria and propionic aciduria. Other diseases were diagnosed in less than 10 cases. CONCLUSION: Though the incidence of individual organic acidemia is low, the overall incidence of organic acidemia as a whole seems to be relatively high in Korea. Compared with the results of organic acid analysis that were reported three years ago, we couldn't find a new disease and the difference of the relative incidences of high incident diseases. We were apprehensive of the errors that was owing to the short study period(3 years), but the relative incidences of our study(8 years) were similar to the results of organic acid analysis that were reported three years ago.

Organic acidemias in Korea / 한양의대학술지

Since we started organic acid analysis in July 1997, we have collected data about organic acidemias in Korea. The data presented herein constitute our 3 years experience in organic acid analysis. We have collected 712 samples from major university hospitals in all over Korea, which are large enough for relatively accurate estimation of incidence of organic acid disorders. We used solvent extraction method with ethylacetate, MSTFA for derivatization and simultaneously quantitation of 83 organic acids. Out of 712 patients sample, 498 samples (70%) showed no evidence of organic acid abnormalities. Out of the 214 remaining samples, we found very diverse disorders such as methylmalonic aciduria (6), propionic aciduria (10), biotinidase deficiency (6), maple syrup urine disease (3), isovaleric aciduria (4), tyrosinemia type II (4), tyrosinemia type IV (1), glutaric aciduria type I (1), glutaric aciduria type II (22), 3-methylglutaconic aciduria type I (3), 3-methylglutaconic aciduria type III (7), HMG-CoA lyase deficiency (1), hyperglyceroluria (2), cytosolic 3-ketothiolase deficiency (55), mitochondrial 3-ketothiolase deficiency (3), 3-hydroxyisobutyric aciduria (2), L-2-hydroxyglutaric aciduria (2), fumaric aciduria (2), lactic aciduria with combined elevation of pyruvate (most likely PDHC deficiency) (28), lactic aciduria without combined elevation of pyruvate (most likely mitochondrial respiratory chain disorders) (35), SCAD deficiency (3), MCAD deficiency (1), 3-methylcrotonylglycineuria (1), orotic aciduria (most likely urea cycle disorders) (7) and 2-methylbranched chain acyl-CoA dehydrogenase deficiency (1). In conclusion, although the incidence of individual organic acidemia is low, the incidence of overall organic acidemia is relatively high in Korea. Most of the patients showed some signs of neurological dysfunction. Therefore, organic acid analysis should be included in the diagnostic work up of all neurological dysfunctions.

Urine Organic Acid Analysis of Patients with Febrile Seizures / 소아과

PURPOSE: Febrile seizure, the most common seizure disorder in children between 6 months and 5 years of age, is mostly caused by viral infections, except severe CNS infection. It can also be caused by disorders in organic acid metabolism, especially accompanied by fever. Therefore we decided to investigate the relationship between children with febrile seizures and disorders in organic acid metabolism. METHODS: We examined 54 children with febrile seizure who visited Chunchon Sacred Heart Hospital Emergency Department from February 2002 to January 2004. We conducted urine organic acid analysis, CBC, urine analysis, serum ammonia and gas analysis. RESULTS: Thirteen(24.1%) patients showed ketonuria, eight(14.8%) patients showed lactic aciduria and ketonuria, two(3.7%) patients showed pyruvic aciduria, and one(1.8%) showed mandelic aciduria. CONCLUSION: Twenty four of 54(44.4%) showed abnormal findings in urine organic acid analysis. Most results are ketonuria or lactic aciduria with ketonuria. They may show in fasting, severe infection or ketolytic defect(ex, 3-ketothiolase deficiency). Patients with 3-ketothiolase deficiency, can develop seizures during fever, and fasting state. Therefore further evaluation is necessary.

Fermentative production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) by recombinant Aeromonas hydrophila 4AK4 (pTG01) / 生物工程学报

Copolyesters consisting of 3-hydroxybutyrate (3HB) and 3-hydroxyhexanoate (3HHx) (PHBHHx), a new type of biodegradable material, are receiving considerable attentions recently. The material properties are strongly related to the 3HHx fraction of PHBHHx. As the 3HHx fraction increase, crystallinity and melting point of PHBHHx decrease, flexibility and tractility increase. PHBHHx of different 3HHx fraction can meet different demands of commercial application and research. Aeromonas are the best studied PHBHHx-producing strains. Recent studies have been focused on optimizations of fermentative culture media and culture conditions for low-cost and efficient fermentative production. Aliphatic substrates such as long-chain fatty acid and soybean oil were used in the PHBHHx fermentation as the sole carbon source and energy source. Two-stage fermentation method was also developed for more efficient PHBHHx production. While studies on Aeromonas hydrophila revealed that the monomer composition of PHBHHx could not easily be regulated by fermentative process engineering methods such as changing substrates and fermentative conditions because precursors involved in the PHBHHx synthesis were all from the beta-oxidation pathway. In this study, phbA gene encoding beta-ketothiolase and phbB gene encoding acetoacetyl-CoA reductase were introduced into a PHBHHx-producing strain Aeromonas hydrophila 4AK4 so as to provide a new 3HB precursors synthesis way. phbA gene encodes beta-ketothiolase which can catalyze two acetyl-CoA to form acetoacetyl-CoA; phbB gene encodes acetoacetyl-CoA reductase catalyzing acetoacetly-CoA into 3HB-CoA which is the precursor of 3HB. The introduced novel 3-hydroxybutyrate precursor synthesis pathway allowed the recombinant strain to use unrelated carbon source such as gluconate to provide 3HB precursors for PHBHHx synthesis. Shake-flask experiments were carried out to produce PHBHHx of controllable monomer composition and fermentations in 5 L fermentor were also proceeded for confirmation of these result in large-scale culture. In flask culture, it was possible to reduce the 3HHx mol fraction in PHBHHx from 15 % in the wild type to 3% - 12% in the recombinant by simply changing the ratio of gluconate to lauric acid in the culture media. When lauric acid was used as the sole carbon source, 51.5 g/L Cell Dry Weight (CDW) containing 62 % PHBHHx with 9.7 % 3HHx mol fraction was obtained in 56 hours of fermentation in a 5 liter fermentor. When co-substrates of sodium gluconate and lauric acid (1:1) were used as carbon sources, 32.8 g/L CDW containing 52 % PHBHHx with 6.7% 3HHx mol fraction was obtained in 48 hours of fermentation. These results showed the possibility for fermentative production of PHBHHx with controllable monomer composition.

Organic Acidemias in Korea: Three Years Experience of Organic Acid Analysis

PURPOSE: We have done this retrospective study to know the relative incidences and clinical manifestations of organic acidopathies in Korea. METHODS: The results of quantitative organic acid analysis of 1,125 samples of 712 patients, referred from Jul. 1997 to Jun. 2000, were analyzed retrospectively according to four age groups (-2 mon, 3 mon-2 year, 3 years-12 years, over 12 years) and major clinical manifestations. Quantification of 83 organic acids was done with gas chromatography and mass spectrometry(GC/MS). RESULTS: We diagnosed 214 patients with 27 diseases of organic acid metabolism during this study period. Diseases found more than 10 cases are cytosolic 3-ketothiolase deficiency, mitochondrial repsiratory chain disorders, PDHC deficiency, glutaric aciduria type II and propionic aciduria. Other diseases were diagnosed in less than 10 cases, mostly one or two cases during this study period. Most of the patients had some symptoms of neurological dysfunction such as seizure activity(195 patients), developmental delay(122), mental retardation(99), hypotonia(84), movement disorders(81) and vomiting(68). CONCLUSION: Though the incidence of individual organic acidemia is low, the overall incidence of organic acidemia as a whole seems to be relatively high in Korea. Most of the patients showed some signs of neurological dysfunction.