Classic homocystinuria is due to deficiency of cystathionine beta‐synthase (CBS), a pyridoxine‐dependent enzyme that, depending on the molecular variants, may be co‐factor responsive. Elevated methionine is often used as the primary analyte to detect CBS deficiency (CBSD) on newborn screening (NBS), but is limited by increased detection of other biochemical disorders with less clear clinical significance such as methionine aminotransferase (MAT) I/III heterozygotes. Our state has implemented a two‐tier NBS algorithm for CBSD that successfully reduced the number of MATI/III heterozygotes, yet effectively detected a mild, co‐factor responsive form of CBSD. After initial diagnosis, newborns with CBSD often undergo a pyridoxine challenge with high‐dose pyridoxine to determine responsiveness. Here we describe our NBS‐identified patient with a mild form of pyridoxine responsive CBSD who developed respiratory failure and rhabdomyolysis consistent with pyridoxine toxicity during a pyridoxine challenge. This case highlights the need for weight‐based dosing and duration recommendations for pyridoxine challenge in neonates.

中文翻译：

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由两层新生儿筛查发现的关于胱硫醚β-合酶缺乏症中吡x醇毒性的警示性故事强调了需要明确的吡ido醇剂量指南。

经典的高半胱氨酸尿症是由于缺乏胱硫醚β合酶（CBS）引起的，该酶是一种依赖吡ido醇的酶，取决于分子的变体，可能对辅因子有反应。甲硫氨酸升高通常用作新生儿筛查（NBS）时检测CBS缺乏症（CBSD）的主要分析物，但由于对其他生化异常（如蛋氨酸氨基转移酶（MAT）I / III杂合子）的检测增加而受到限制。我们的州对CBSD实施了两层NBS算法，该算法成功减少了MATI / III杂合子的数量，但有效地检测到CBSD的轻度，辅因子响应形式。初步诊断后，患有CBSD的新生儿通常会接受高剂量吡ido醇的吡ido醇攻击，以确定反应性。在这里，我们描述了由NBS鉴定的轻度对吡pyr醇反应性CBSD的患者，在吡ido醇攻击期间发生呼吸衰竭和横纹肌溶解，并伴有吡ido醇毒性。这种情况突显了新生儿对吡x醇挑战的基于体重的剂量和持续时间的建议。