ABSTRACT
Objective:To summarize the clinical phenotype and genetic characteristics of one child patient with mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency (mHS) caused by HMGCS2 gene mutation. Methods:One child patient with mHS who received treatment in Chongqing University Three Gorges Hospital on April 10, 2020 was included in this patient. The child was hospitalized due to cough, shortness of breath and deep coma. After admission, gas chromatography-mass spectrometry of the blood and urine samples and high-throughput whole genome sequencing were performed. The pedigree of the child with gene mutation was analyzed. The child was diagnosed with mHS. Related publications published by June, 2020 were searched in Wanfang database, Chinese Journal Full Text Database, PubMed and HGMD databases using search terms "mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency", "HMGCS2" "mHS deficiency". Forty-three papers addressing mHS deficiency were retrieved. The clinical phenotype and genotypes of the child with HMGCS2 mutation were summarized. Results:As of June 2020, there were 44 children with mHS deficiency, including the child reported in this study. These children consisted of 15 males, 11 females and 18 unknown genders. Among these children, 29 were aged 0-24 months, 4 were aged > 24 months, 6 had no symptoms, and 5 were of unknown age of disease onset. The first symptoms of most children were fever, cough, acute gastroenteritis, and coma. Twenty-seven children had hypoglycemia, 21 children had metabolic acidosis, 15 children developed hepatomegaly, 16 children had increased FFA/D-3-HB, and 10 children were tested 4-hydroxy-6-methyl-2-pyrone positive. The child included in this study had hepatomegaly, elevated alanine aminotransferase and metabolic acidosis. Gas chromatography-mass spectrometry results showed that a variety of metabolites were increased. Tandem mass spectrometry results showed that C40 level was elevated, and long-chain carnitine contents were increased. High-throughput whole genome sequencing results revealed that there were two heterozygous mutations in HMGCS2 gene, (NM_0055) c.559+1G > A; c. 758 T > C heterozygous mutation. Sanger sequencing and parental origin analysis showed that the mutations in this child were from parents. The two gene mutations in this child were new mutations, which have not been reported in China and countries outside China. According to the criteria and guidelines for interpretation of ACMG sequence variation, the variation was determined to be pathogenic. Conclusion:When a child has hypoketotic hypoglycemia and/or metabolic acidosis, increased FFA/D-3-HB and acetylcarnitine levels, mHS deficiency should be considered. HMGCS2 gene examination can help diagnose mHS deficiency.
ABSTRACT
Objective: To clone and characterize a 3-hydroxy-3-methylglutaryl-CoA synthase (HMGS) gene DnHMGS in Dendrobium nobile. Methods: RT-PCR and RACE technologies were used for gene cloning. Characteristics including the physicochemical properties and conserved domain of the deduced DnHMGS protein were determined by a series of bioinformatics tools. The analyses of multiple alignment and phylogenetic tree were performed by DNASTAR and MEGA softwares, respectively. qRT-PCR was employed to examine the tissue specific expression pattern of DnHMGS. Results: The full length cDNA of DnHMGS was 1 816 bp (GenBank accession No. KX789180) and encoded a 474-amino-acid protein with a molecular weight of 52 458.47 and an isoelectric point (pI) of 5.98. The deduced DnHMGS protein, like other HMGS proteins, constituted typical domain and active site. Multiple sequence alignment and phylogenetic analyses demonstrated that DnHMGS was closely related to Ananas comosus, rice, and maize monocots. Proteins analysis revealed that DnHMGS was expressed in the three included organs. The transcripts were the most abundant in the leaves with more than twice that in the roots and stems. However, the expression of DnHMGS changed to stems > leaves > roots when D. nobile infected by Mycena sp. Conclusion: The full length cDNA of DnHMGS is indentified from D. nobile for the first time. Molecular characterization of DnHMGS will be useful for further functional elucidation of the gene involving in isoprenoid biosynthesis pathway in D. nobile, and help us understand the molecular mechanism of Mycena sp. which better encourages the biosynthesis of dendrobine.