• Applied Biological Chemistry
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• v.21 no.1
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• pp.11-15
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• 1978

Alloisoleucine from the plasma of maple syrup disease affected patients was separated from isolecine and identified by gas liquid chromatography and mass spectrometry.

• Journal of Genetic Medicine
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• v.11 no.1
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• pp.22-26
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• 2014

Maple syrup urine disease (MSUD) is a disorder that involves the metabolism of branched chain amino acids, arising from a defect in branched-chain ${\alpha}$-keto acid dehydrogenase complex. Mutations have been identified in the BCKDHA, BCKDHB, or DBT genes, which encode different subunits of the BCKDH complex. Although encephalopathy and progressive neurodegeneration are its major manifestations, the severity of the disease may range from the severe classic type to milder intermediate variants. We report two Korean siblings with the milder intermediate MSUD who were diagnosed with MSUD by a combination of newborn screening tests using tandem mass spectrometry and family genetic screening for MSUD. At diagnosis, the patients' plasma levels were elevated for leucine, isoleucine, valine, and alloisoleucine, and branched-chain ${\alpha}$-keto acids and branched-chain ${\alpha}$-hydroxy acids were detected in their urine. BCKDHA, BCKDHB, and DBT analysis was performed, and two novel mutations were identified in BCKDHB. Our patients were thought to have the milder intermediate variant of MSUD, rather than the classic form. Although MSUD is a typical metabolic disease with poor prognosis, better outcomes can be expected if early diagnosis and prompt management are provided, particularly for milder forms of the disease.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.23 no.2
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• pp.31-38
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• 2023

Maple syrup urine disease (MSUD) is an autosomal recessive metabolic disorder caused by a deficiency in branched chain α-keto acid dehydrogenase (BCKAD). Between 1997, when Korea's MSUD case was first reported, and 2023, 14 cases were reported in the literature. 29% of the cases experienced developmental delay, and 29% expired. The prevalence of MSUD in Korea was estimated to be 1 in 230,000. Of 21 MSUD patients currently being treated at the Korea Genetics Research Center, 19 were detected through newborn screening program, and 2 were diagnosed by the symptoms. 14 MSUD patients had confirmed genetic mutations; 6 (43%) were BCKDHA and 8 (57%) were BCKDHB. In one case, a large deletion was observed. 4 patients had leucine levels above 2,000 (umo/L), and post-dialysis diet therapy was initiated in the newborn period. No patient required further dialysis as diet therapy and regular monitoring proved highly effective. Most MSUD patients were growing normally; weight and height growth were above the 50th percentile in 76% of the cases while BMI values were higher than normal in 71% of cases. Developmental delays were observed only in 2 cases (10%) and anticonvulsant use in 3 cases (14%). With newborn screening available to all Korean infants, early diagnosis and intervention should allow most patients to remain asymptomatic. However, ongoing surveillance, dietary management and continued patient compliance as well as rapid correction of acute metabolic decompensations remain critical to a favorable long-term prognosis.