20个X连锁肾上腺脑白质营养不良家系的产前诊断

Prenatal diagnosis of X-linked adrenoleukodystrophy in 20 pedigrees

目的总结X连锁肾上腺脑白质营养不良(X-linked adrenoleukodystrophy,X-ALD)家系的基因变异及产前诊断特点,探讨产前诊断在预防X-ALD患儿出生中的应用价值。方法回顾性纳入2012年11月至2019年3月在北京大学第一医院就诊的20个X-ALD家系。取先证者、家系成员的外周血标本及母亲再孕胎儿的羊水或绒毛标本,提取基因组DNA,应用聚合酶链反应-Sanger测序检测致病基因ABCD1(ATP-binding cassette subfamily D member 1)的变异情况。同时选取ABCD1基因附近的5个短串联重复序列位点进行连锁分析,以排除母源DNA污染。采用描述性统计分析总结X-ALD家系的基因变异及产前诊断特点。结果在20个X-ALD家系中,发现了20种ABCD1基因变异。3例二代测序未检出ABCD1基因变异的先证者均通过聚合酶链反应-Sanger测序检出变异。20例先证者的母亲中3例未发现携带变异,17例携带变异。20例母亲的24例次产前诊断(胎儿24例)中8例胎儿检出ABCD1基因变异(引产终止妊娠),16例胎儿未检测到变异,均活产分娩。引产或者生后子代验证结果与产前诊断一致。结论致病基因ABCD1无热点变异,变异大部分遗传自母亲,聚合酶链反应-Sanger测序是检测该基因变异的有效手段;对生育过X-ALD患者的母亲再孕时进行产前诊断,可以有效地预防患儿出生。

Objective To summarize the characteristics of genetic variation and prenatal diagnosis in pedigrees with X-linked adrenoleukodystrophy(X-ALD)and elucidate the value of prenatal diagnosis in preventing the birth of children with X-ALD.Methods Twenty pedigrees,clinically diagnosed with X-ALD in Peking University First Hospital from November 2012 and March 2019,were included in this retrospective study.Genomic DNA was extracted from peripheral blood and amniotic fluid or chorionic villi samples of probands and their families for detecting variants in ATP-binding cassette subfamily D member 1(ABCD1)gene using polymerase chain reaction(PCR)-Sanger sequencing.Linkage analysis was also performed on five microsatellite markers near ABCD1 gene to exclude maternal contamination.Characteristics of ABCD1 gene variants and prenatal diagnosis of X-ALD pedigrees were summarized by descriptive statistics.Results Twenty ABCD1 gene variants were identified in the 20 pedigrees.The variants in three probands that were not detected by next-generation sequencing were identified by PCR-Sanger sequencing.Among the mothers of the 20 probands,17 carried ABCD1 variants and three did not.We performed 24 prenatal diagnoses on 20 pregnancies(24 fetuses)and identified eight fetuses with variants who were finally terminated.The 16 cases without variants were born alive.The validation results obtained after termination or delivery were consistent with those performed prenatally.Conclusions No hotspot variants in ABCD1 gene are detected in these X-ALD patients and most variants are maternally inherited.PCR-Sanger sequencing is an effective method for detecting ABCD1 variants.Prenatal diagnosis for mothers who had a body with X-ALD could prevent another one from birth.