Giorgio A J, Trowbridge M, Boone A W, Patten R S
N Engl J Med. 1976 Aug 5;295(6):310-3. doi: 10.1056/NEJM197608052950604.
Two brothers 62 and 70 years old, without evidence of vitamin B12 lack, excreted 12 to 115 mg of methylmalonic acid daily (normal, less than 9 mg per day). Neither had anemia or hepatic dysfunction, and serum vitamin B12 concentrations ranged from 369 to 800 pg per milliliter. The propositus, the younger brother, continued to excrete excessive methylmalonate, 103 to 115 mg per day, after 2000 mug of parenterally administered vitamin B12 at the fifth and 11th months of study. Leukocyte activities of the cobalamin-linked enzyme methylmalonyl coenzyme A mutase were respectively reduced in the propositus and his brother, to 0.04 and 0.11 nmoles of 3-(14)-C Ls methylmalonyl coenzyme A metabolized per hour per milligram of leukocyte protein (normal, 0.286 +/- 0.079 [S.D.]). These activities were not enhanced by 2 mug of 5'-deoxyadenosylcobalamin added to the assays. A heritable benign form of adult methylmalonic aciduria rather than vitamin B12 lack best explains these findings.
两名分别为62岁和70岁的兄弟，无维生素B12缺乏证据，每日排泄甲基丙二酸12至115毫克（正常每日少于9毫克）。两人均无贫血或肝功能障碍，血清维生素B12浓度范围为每毫升369至800皮克。先证者，即弟弟，在研究的第5个月和第11个月经肠道外给予2000微克维生素B12后，仍继续排泄过量的甲基丙二酸，每日103至115毫克。先证者及其兄弟中钴胺素相关酶甲基丙二酰辅酶A变位酶的白细胞活性分别降低，每毫克白细胞蛋白每小时代谢3 -（14）-C - L - 甲基丙二酰辅酶A的量分别为0.04和0.11纳摩尔（正常为0.286± 0.079[标准差]）。测定中加入2微克5'-脱氧腺苷钴胺素后，这些活性并未增强。成人甲基丙二酸尿症的一种遗传性良性形式而非维生素B12缺乏最能解释这些发现。
