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A neonatal‐onset succinyl‐CoA:3‐ketoacid CoA transferase (SCOT)‐deficient patient with T435N and c.658‐666dupAACGTGATT p.N220_I222dup mutations in the OXCT1 gene
Author(s) -
Fukao Toshiyuki,
Ishii Tomohiro,
Amano Naoko,
Kursula Petri,
Takayanagi Masaki,
Murase Keiko,
Sakaguchi Naomi,
Kondo Naomi,
Hasegawa Tomonobu
Publication year - 2010
Publication title -
journal of inherited metabolic disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 102
eISSN - 1573-2665
pISSN - 0141-8955
DOI - 10.1007/s10545-010-9168-5
Subject(s) - ketonuria , compound heterozygosity , medicine , endocrinology , mutation , ketone bodies , complementation , chemistry , gene , biochemistry , metabolism , mutant , diabetes mellitus
Succinyl‐CoA:3‐ketoacid CoA transferase (SCOT) deficiency causes episodic ketoacidotic crises and no apparent symptoms between them. Here, we report a Japanese case of neonatal‐onset SCOT deficiency. The male patient presented a severe ketoacidotic crisis, with blood pH of 7.072 and bicarbonate of 5.8 mmol/L at the age of 2 days and was successfully treated with intravenous infusion of glucose and sodium bicarbonate. He was diagnosed as SCOT deficient by enzymatic assay and mutation analysis. At the age of 7 months, he developed a second ketoacidotic crisis, with blood pH of 7.059, bicarbonate of 5.4 mmol/L, and total ketone bodies of 29.1 mmol/L. He experienced two milder ketoacidotic crises at the ages of 1 year and 7 months and 3 years and 7 months. His urinary ketone bodies usually range from negative to 1+ but sometimes show 3+ (ketostix) without any symptoms. Hence, this patient does not show permanent ketonuria, which is characteristic of typical SCOT‐deficient patients. He is a compound heterozygote of c.1304C > A (T435N) and c.658‐666dupAACGTGATT p.N220_I222dup. mutations in the OXCT1 gene. The T435N mutation was previously reported as one which retained significant residual activity. The latter novel mutation was revealed to retain no residual activity by transient expression analysis. Both T435N and N220_I222 lie close to the SCOT dimerization interface and are not directly connected to the active site in the tertiary structure of a human SCOT dimer. In transient expression analysis, no apparent interallelic complementation or dominant negative effects were observed. Significant residual activity from the T435N mutant allele may prevent the patient from developing permanent ketonuria.