ABO phenotype protected reproduction as it is based on specific fucosylations.

The molecular biological relationship between human fertility and the formation of the ABO(H) blood group phenotype is evident in the rare (Oh) or <i>Bombay</i> blood type, which, based on the history of his own family, the <i>Darwin/Wedgewood Dynasty</i>, Charles Darwin would have interpreted as resulting from reduced fertility in consanguinities. In its native form, the <i>Bombay</i> type occurs in individuals with an extremely rare genotype (h/h;se/se), in whom the fucosyltransferases FUT1 and FUT2 are not produced due to point mutations. These enzymes, which are encoded on chromosome 19, are epistatically connected with the A and B allelic glycotransferase functions encoded on chromosome 9, and the fucosyl residues provide the functional-structural basis for the formation of any ABO(H) phenotype on the cell surface or in secretions and plasma proteins. Immunoglobulins are also heavily fucosylated, and fucosyl residues appear, via developmental variations in their positions on cell surfaces and on the heavy chains of immunoglobulins, to increase or reduce antibody-mediated cellular cytotoxicity involving physiological anti-self-reactivity; moreover, by regulating the assembly and intracellular signalling of precursor B cell receptors, the core fucosylation of immunoglobulin heavy chains represents a key mechanism in clonal selection. In fact, the seminal plasma of leukospermic infertile men has been reported to exhibit high levels of poorly core-fucosylated IgG. Thus, when antibody-dependent cellular cytotoxicity can be increased 50-fold simply by removing the single fucose residue from the Fc glycan, in <i>Bombay </i>type individuals, the non-somatic glycosylation processes of embryogenic stem cell-to-germ cell transformation are most likely exposed to metabolic competition with multiple glycosidic sites of poorly fucosylated, glycan-depleted immunoglobulins, suggesting to promote anti-self-reactive cellular cytotoxicity in male gamete performance.

人类生育力与ABO(H)血型表型（ABO(H) blood group phenotype）形成之间的分子生物学关联，在罕见的Oh型（或称Bombay血型）中体现得尤为直观。结合其自身所属的达尔文-韦奇伍德家族（Darwin/Wedgewood Dynasty）的谱系史，查尔斯·达尔文（Charles Darwin）或许会将该血型表型归因于近亲婚配所导致的生育力降低。天然状态下的Bombay血型见于携带极为罕见基因型（h/h;se/se）的个体，这类个体因点突变无法合成岩藻糖基转移酶FUT1（fucosyltransferase FUT1）与FUT2（fucosyltransferase FUT2）。这两种酶由19号染色体编码，与9号染色体上编码的A、B等位基因糖基转移酶功能存在上位性关联；岩藻糖残基为细胞表面、分泌物及血浆蛋白上任意ABO(H)表型的形成提供了功能结构基础。免疫球蛋白（immunoglobulin）同样存在大量岩藻糖基化修饰，而岩藻糖基残基通过其在细胞表面及免疫球蛋白重链上的位置发育变化，可增强或减弱涉及生理抗自身反应性的抗体介导细胞毒性；此外，通过调控前B细胞受体的组装与细胞内信号转导，免疫球蛋白重链的核心岩藻糖基化是克隆选择的关键机制。已有研究报道，白细胞精子症不育男性的精浆中，核心岩藻糖基化不全的IgG水平显著升高。据此可知，若仅去除Fc聚糖上的单个岩藻糖残基，即可将抗体依赖性细胞毒性提升50倍；那么在Bombay血型个体中，胚胎干细胞向生殖细胞转化过程中的非体细胞糖基化过程，极有可能与大量岩藻糖缺乏、聚糖缺失的免疫球蛋白的糖基位点产生代谢竞争，这提示该过程会促进雄配子功能中的抗自身反应性细胞毒性。