Genetic diagnosis of one pregnant woman with severe mental retardation and prenatal diagnosis of her fetus

This study aims to investigate the genetic mechanisms of one pregnant woman with severe mental retardation, hypoevolutism, and adverse history of pregnancy and delivery, and to perform the prenatal diagnosis towards the fetus, aiming to provide guidance for her future fertility. High-resolution chromosome assay (HRCA), fluorescence in situ hybridization (FISH), and whole genome DNA microarray (WGDM) were performed for the pregnant woman’s testing. Amniocentesis was used to detect the fetal DNA chips. The chromosome of the pregnant woman was 47, XX, del (18) (q21.3), + ish mar (D15Z1 +, SNRPN +) [82]/46, XX, del (18) (q21.3) [18], among which 15q11. 2q12 existed the duplication of one 3.044 Mb fragment containing 17 OMIM genes (NIPA1, and SNRPN etc.), which were related to mental retardation, autism, and hypoevolutism. 18q21.33q23 existed the deletion of one 17.992 Mb fragment containing 39 OMIM genes (TNFRSF11A, and PHLPP1, etc.), which were related to mental retardation, overall hypoevolutism, and cleft palate. The fetus inherited maternal 18th abnormal chromosome, namely the fetal 18q21.33q23 existed the deletion of one 17.992 Mb fragment. After genetic counseling, the patient’s families strongly demanded the termination of pregnancy, so the pregnancy was terminated at the 21st gestational week. In conclusion, HRCA, FISH, and WGDM had their advantages and disadvantages, respectively. Therefore, the comprehensive application of the above techniques based on patient’s conditions could better diagnose the relationships between genetic mechanism and clinical phenotype.