PEX7基因致病性新突变致肢根型点状软骨发育不良Ⅰ型胎儿一例

Rhizomelic chondrodysplasia punctata typeⅠin a fetus due to novel pathogenic mutation in PEX7 gene

本文报道了1例肢根型点状软骨发育不良Ⅰ型胎儿。孕23周超声检查提示胎儿双侧股骨多处骨折,干骺端粗大,双侧肱骨严重短小、增粗、弯曲,且有多处骨折声像,部分表现为骨折后骨痂形成。孕23周+2终止妊娠,取引产胎儿皮肤组织样本及父母双方外周血样本行全外显子组高通量测序,结果发现,胎儿6号染色体PEX7基因移码突变c.179delT(p.F61Lfs*13),且该染色体137105182-137245871区间内杂合缺失,大小约141 kb,该缺失片段内包括PEX7基因。上述突变属于复合杂合突变,且均尚未报道,判定为致病性突变。此例胎儿临床表型严重可能是由于胎儿存在移码突变和大片段缺失突变共同作用造成PEX7基因严重损伤所致。

We report a case of a fetus with rhizomelic chondrodysplasia punctata typeⅠ.Ultrasound examination of the pregnant women at 23 weeks of gestation showed multiple fractures in bilateral femurs,thick metaphysis,severely short,thickened and curved bilateral humerus with multiple fracture images,some of which were callu formation after fracture.The pregnancy was terminated at 23+2 gestational weeks,samples of fetal skin tissue were taken after birth,and parental peripheral blood was collected for whole exome sequencing,which revealed a frameshift mutation c.179delT(p.F61Lfs*13)in the PEX7 gene of chromosome 6,and the heterozygous deletion(141 kb)occurred in the region of chromosome 6137105182-137245871,covering the pathogenic gene PEX7.The analysis of parental samples suggested that the mutations were compound heterozygous mutations,none of which had been previously reported and were determined to be pathogenic mutations.The severe clinical phenotype of this case may be caused by severe damage of PEX7 gene contributed by the frameshift mutation and large fragment deletion mutations.