Scot Gene Mutation And Clinical Analysis In Ketone Utilization Defect Children

Background Ketone body are major vectors of energy transfer from liver to extrahepatic tissues[1] which are mainly produced in liver. Ketoscidosis occurs commonly under the condition of a marked increase in ketone body concentration. Succinyl CoA: 3-oxoacid CoA transferase(SCOT) is the key enzyme of ketone body utilization, existing in the mitochondrial matrix of multiple organs. SCOT catalyzes the reversible transfer of a CoA moiety from succinyl CoA to the ketone body acetoacetate, the first step of ketone- body utilization. Then, acetoacetyl CoA cleavage to two acetyl CoA molecules which are capable of entering the tricarboxylic acid cycle. Elegant studies revealed that, the special mechanism of SCOT catalyzing the formation of acetoacetyl CoA is generating the thioester with coenzyme A and binding the ADP groups of coenzyme A in the form of non–covalent bond. The formation of thioester occurs in on the glutamate residue344 of SCOT peptide chain. Hereditary deficiency of SCOT is an autosomal recessive inborn error and is part of the differential diagnosis of childhood ketoacidosis , a frequently occurring condition. In contrast with most organic acidemias, no diagnostic metabolites are observed in blood and urine samples from SCOT-deficient patients although the ketone bodies acetoacetate and 3-hydroxybutyrate are elevated. Since the first description of SCOT deficiency, only 18 [1-12]]affedted probands and 10 mutations have been reported[3,5,6,8-12].Objective To explore the mutations types of Chinese SCOT-deficient patient and the relationship between the genotype and phenotype.Method Total RNA was extracted from peripheral blood of clinical highly suspected children and 50 health children as control, the whole coding sequence of SCOT cDNA was amplified by RT-PCR followed by T-Clone and sequencing.DNA was teseted if RNA was tested abnormal; observed the clinical manifestions of the child who had SCOT gene mutations.Result One of there patients was found with skipping of exon 12, detection in DNA level showed a single-base substitution(c1147G>A)in exon 12. The pre-mRNA secondary structure analysis revealed a change of pre-mRNA secondary structure after substitution while the ESE analysis told us that the purine-rich region was unlikely acting as ESEs. The other two were found no mutations. The child who had 12 exon skip of SCOT gene mainly manifested as recurrent infection induced severe ketoacidosis, but the symptoms could released by active salvage, and the patient could be as normal as other children during the intermittent episodes.Conclusion Whether the substitution of exon 12(c1147G>A)resulted in the skipping of 12 by disrupting the pre-RNA secondary structure needs to be further confirmed. Thjs mutation had not been reported before. Infection should be avoided if the child has this kind of mution, and treatment should be active.