Maple urine syrup disease (MSUD) is an autosomal recessive disorder characterized by deficient activity of the branched-chain alpha ketoacid dehydrogenase (BCKAD) enzymatic complex due to biallelic variants in the alpha (BCKDHA) or beta (BCKDHB) subunits or the acyltransferase component (DBT). Treatment consists in leucine (LEU), isoleucine (ILE), and valine (VAL) (branched-chain amino acids) dietary restriction and strict metabolic control. to determine the characteristics of the Chilean cohort with MSUD currently in follow-up at Instituto de Nutrición y Tecnología de los Alimentos, during the 1990–2017 period Retrospective analytical study in 45 MSUD cases. Measured: biochemical parameters (LEU, ILE, and VAL), anthropometric evaluation, and neurocognitive development. In 18 cases undergoing genetic study were analyzed according to the gene and protein location, number of affected alleles, and type of posttranslational modification affected. Then, 45 patients with MSUD diagnosis were identified during the period: 37 were alive at the time of the study. Average diagnosis age was 71 ± 231 days. Average serum diagnosis LEU concentrations: 1.463 ± 854.1 μmol/L, VAL 550 ± 598 μmol/L and ILE 454 ± 458 μmol/L. BCKDHB variants explain 89% cases, while BCKDHA and DBT variants explain 5.5% of cases each. Variants p.Thr338Ile in BCKDHA, p.Pro240Thr and p.Ser342Asn in BCKDHB have not been previously reported in literature. Average serum follow-up LEU concentrations were 252.7 ± 16.9 μmol/L in the <5 years group and 299 ± 123.2 μmol/L in ≥5 years. Most cases presented some degree of developmental delay. Early diagnosis and treatment is essential to improve the long-term prognosis. Frequent blood LEU measurements are required to optimize metabolic control and to establish relationships between different aspects analyzed.

中文翻译：

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枫糖浆尿病：智利45例诊治特点

枫尿糖浆病 (MSUD) 是一种常染色体隐性遗传疾病，其特征是支链 α 酮酸脱氢酶 (BCKAD) 酶复合物由于 α ( BCKDHA ) 或β ( BCKDHB ) 亚基或酰基转移酶成分中的双等位基因变异而缺乏活性。DBT）。治疗包括亮氨酸 (LEU)、异亮氨酸 (ILE) 和缬氨酸 (VAL)（支链氨基酸）饮食限制和严格的代谢控制。在 1990 年至 2017 年期间，在 Instituto de Nutrición y Tecnología de los Alimentos 中确定智利 MSUD 队列的特征，对 45 个 MSUD 病例进行回顾性分析研究。测量：生化参数（LEU、ILE 和 VAL）、人体测量学评估和神经认知发育。根据基因和蛋白质的位置、受影响的等位基因数量和受影响的翻译后修饰类型，对 18 例进行遗传研究的病例进行了分析。然后，在此期间确定了 45 名患有 MSUD 诊断的患者：37 名在研究时还活着。平均诊断年龄为 71 ± 231 天。BCKDHB变体解释了 89% 的病例，而BCKDHA和DBT变体分别解释了 5.5% 的病例。在多个变p.Thr338Ile BCKDHA，p.Pro240Thr和p.Ser342Asn在BCKDHB还没有文献报道过。<5 年组的平均血清 LEU 随访 LEU 浓度为 252.7 ± 16.9 μmol/L，≥5 年组为 299 ± 123.2 μmol/L。大多数病例出现一定程度的发育迟缓。早期诊断和治疗对于改善长期预后至关重要。需要频繁的血液 LEU 测量来优化代谢控制并建立分析的不同方面之间的关系。