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目的对COL2A1基因(typeⅡcollagen gene)G504S突变导致的先天性脊柱骨骺发育不良(SEDC)家系的2例中期妊娠患者进行产前分子诊断。方法分别对患者于19+3孕周和18+6孕周进行羊膜囊穿刺术抽取羊水,提取羊水脱落细胞DNA,对COL2A1基因的第23外显子扩增,对其产物测序。同时第1例胎儿从17+3孕周~27+3孕周、第2例胎儿从16+1孕周~19+1孕周对股骨长度进行B超动态检测。结果COL2A1的23外显子测序结果显示第1例胎儿带有与母亲同样的COL2A1基因G504S突变。第2例胎儿COL2A1基因无突变。B超的追踪检测显示2例胎儿颅骨双顶径都与孕龄相符。第1例患病胎儿股骨增长随孕龄的增加而逐渐减慢,但孕23周前减慢不十分明显。病例2的胎儿股骨长度与孕龄相符,现继续妊娠观察。于第27+5孕周对第1例患病胎儿行引产术后,影像学检测显示胎儿脊柱扁平、长骨明显短小,证实胎儿患有SEDC。结论对于有SEDC风险的胎儿进行基因检测非常重要,可以在B超诊断前了解胎儿基因型并明确诊断。B超对胎儿股骨长度的动态检测有助于SEDC的诊断。
Objective To perform prenatal molecular diagnosis of 2 pregnant women with congenital spinal epiphyseal dysplasia (SEDC) caused by COL2A1 G504S mutation. Methods Amniotic fluid was amniocentesis in 19 +3 gestational weeks and 18 +6 gestational weeks. DNA of amniotic fluid exfoliated cells was extracted. The exon 23 of COL2A1 gene was amplified and sequenced. At the same time, the first fetus from 17 +3 gestational weeks to 27 +3 gestational weeks, the second fetus fetus from 16 +1 gestational weeks ~ 19 +1 gestational weeks on the femoral length B-dynamic detection. Results The 23 exon sequencing results of COL2A1 showed that the first fetus had the same COL2A1 G504S mutation as the mother. The second case of fetal COL2A1 gene without mutation. B-tracking test showed that 2 cases of fetal skull biparietal diameter are consistent with gestational age. The first case of diseased fetus femoral growth increases with gestational age and gradually slow down, but not slow down 23 weeks before pregnancy is not very clear. Case 2 fetal femur length and gestational age consistent, now continue to observe the pregnancy. In the 27th +5 gestational weeks on the first case of fetuses fetus line abortion, the imaging examination showed flat fetal spine, long bone was significantly shorter, confirmed that the fetus has SEDC. Conclusions Genetic testing of fetuses at risk for SEDC is important to understand fetal genotypes and confirm diagnosis before B-ultrasound diagnosis. The dynamic detection of fetal femur length by B ultrasound is helpful for the diagnosis of SEDC.