Chudley A E, Knoll J, Gerrard J W, Shepel L, McGahey E, Anderson J
Am J Med Genet. 1983 Apr;14(4):699-712. doi: 10.1002/ajmg.1320140412.
Members of eight Saskatchewan families with fragile (X) X-linked mental retardation were studied in an attempt to relate frequency to age and intelligence. The mean IQ of 37 affected men was 35 (range 10-66). The mean IQ of 32 carriers was 88 (range 57-119), and the mean IQ of 13 females who remain at risk for being carriers, have no affected sons, and who failed to demonstrate the fra(X) was 100 (range 78-126). We demonstrated a significant inverse relationship between age and frequency of the fra(X) in carriers and in affected males. However, we demonstrated a more highly significant inverse relationship between frequency of the fra(X) and IQ in carriers but to a lesser extent in affected males. Of 32 carriers, only 3 (9.4%) did not demonstrate the fra(X) after addition of 5-fluoro-2'-deoxyuridine (FUdR) to the folic acid and thymidine-reduced culture medium. From these data we would recommend that chromosome studies in individuals at risk for fra(X) X-linked mental retardation be carried out at the youngest age and that the addition of FUdR to culture medium is useful in carrier identification. It is clear that, in at least the carriers, a lower expression of the fra(X) is highly significantly correlated to higher intelligence.
对萨斯喀彻温省8个患有脆性X连锁智力障碍家庭的成员进行了研究，试图找出发病率与年龄和智力之间的关系。37名受影响男性的平均智商为35（范围为10 - 66）。32名携带者的平均智商为88（范围为57 - 119），13名仍有成为携带者风险、没有受影响儿子且未表现出脆性X的女性的平均智商为100（范围为78 - 126）。我们发现携带者和受影响男性中，年龄与脆性X的发病率之间存在显著的负相关关系。然而，我们还发现携带者中脆性X的发病率与智商之间存在更高度显著的负相关关系，而在受影响男性中这种关系较弱。在32名携带者中，在叶酸和胸腺嘧啶核苷减少的培养基中添加5 - 氟 - 2'-脱氧尿苷（FUdR）后，只有3人（9.4%）未表现出脆性X。根据这些数据，我们建议对有脆性X连锁智力障碍风险的个体进行染色体研究时应在最年幼时进行，并且在培养基中添加FUdR有助于携带者的识别。很明显，至少在携带者中，脆性X较低的表达与较高的智力高度显著相关。
