Brattström L, Israelsson B, Tengborn L, Hultberg B
Department of Neurology, University Hospital, Lund, Sweden.
J Inherit Metab Dis. 1989;12(4):475-82. doi: 10.1007/BF01802045.
Cystathionine beta-synthase deficiency results in severe homocysteinaemia, precocious arteriosclerosis and frequent thromboembolism. In addition, antithrombin III activity and factor VII are low. Arteriosclerosis seems to be increased in heterozygotes as well (cystathionine beta-synthase gene dosage 50%) but rare in Down syndrome (cystathionine beta-synthase gene dosage 150%). In the present study total plasma homocysteine was high in three homozygotes, slightly increased in 20 obligate heterozygotes but not reduced in nine subjects with Down syndrome when compared to controls. After methionine loading, increases of homocysteine were pathologically high in 14 of 20 heterozygotes but was not, as expected, low in subjects with Down syndrome. Antithrombin III activity and factor VII antigen tended to be low in homozygotes but were normal in heterozygotes. In Down syndrome antithrombin III activity was reduced and factor VII antigen normal. There were no correlations between levels of homocysteine, antithrombin III activity and factor VII antigen. Thus, subjects with Down syndrome seem not to exhibit the expected gene dosage effect on homocysteine metabolism which could explain their reduced proneness to develop arteriosclerosis, nor do antithrombin III activity or factor VII antigen seem to be related to homocysteine metabolism.
胱硫醚β-合酶缺乏会导致严重的高同型半胱氨酸血症、早熟动脉硬化和频繁的血栓栓塞。此外，抗凝血酶III活性和因子VII水平较低。杂合子（胱硫醚β-合酶基因剂量为50%）的动脉硬化似乎也会增加，但在唐氏综合征患者（胱硫醚β-合酶基因剂量为150%）中则较为罕见。在本研究中，与对照组相比，三名纯合子的血浆总同型半胱氨酸水平较高，20名必然杂合子略有升高，但九名唐氏综合征患者并未降低。蛋氨酸负荷后，20名杂合子中有14名的同型半胱氨酸升高幅度呈病理性增高，但正如预期的那样，唐氏综合征患者的同型半胱氨酸升高幅度并不低。抗凝血酶III活性和因子VII抗原在纯合子中往往较低，但在杂合子中正常。在唐氏综合征患者中，抗凝血酶III活性降低，因子VII抗原正常。同型半胱氨酸水平、抗凝血酶III活性和因子VII抗原之间无相关性。因此，唐氏综合征患者似乎未表现出预期的基因剂量对同型半胱氨酸代谢的影响，而这可能解释了他们患动脉硬化倾向较低的原因，抗凝血酶III活性或因子VII抗原似乎也与同型半胱氨酸代谢无关。
