Prenatal diagnosis for a pedigree affected with Wolf-Hirschhorn syndrome due to a subtle chromosomal translocation / 中华医学遗传学杂志

OBJECTIVE@#To make molecular diagnosis of an infant affected with severe developmental delay and multiple birth defects, assisting prenatal diagnosis for the second pregnancy.@*METHODS@#Standard G-banded karyotyping was performed for the fetus and his parents. Single nucleotide polymorphism array (SNP array) was used to detect submicroscopic chromosomal aberration. Fluorescence in situ hybridization (FISH) was employed to determine the parental origin of the aberration.@*RESULTS@#Both the proband and the fetus harbored a 5.4 Mb distal 4p deletion and a 6.9 Mb distal 6q duplication. FISH confirmed that the mother has carried a balanced translocation involving 4p and 6q.@*CONCLUSION@#The unbalanced chromosomal aberration in the proband and the fetus were both derived from the mother. Both patients showed a Wolf-Hirschhorn syndrom phenotype and partial phenotype of 6q trisomy. SNP array combined with FISH are essential for the detection of cryptic chromosomal aberrations which may be missed by coventional karyotyping analysis.

Prenatal diagnosis of three cases of fetal skeletal dysplasia resulting from loss of heterozigosity of short stature homeobox gene / 中华围产医学杂志

Objective To analyze the genotype-phenotype correlation in fetal skeletal dysplasia,and to investigate the methods of prenatal diagnosis and genetic counseling.Methods From May 2016 to November 2017,three gravidas whose fetuses were diagnosed with short stature homeobox (SHOX) gene deficiency were recruited from those receiving invasive prenatal diagnosis and single nucleotide polymorphismarray (SNP-array) due to fetal structural abnormalities detected by prenatal ultrasound scan in Shanghai First Maternity and Infant Hospital,Tongji University School of Medicine.Fetus 1 and 3 were singleton pregnancies and fetus 2 was twin pregnancy.Amniotic fluid cells were isolated and analyzed by karyotyping and SNP-array.Peripheral blood samples were collected from their parents and also analyzed by SNP-array.Results All three fetuses were diagnosed with fetal skeletal dysplasia based on second trimester ultrasound findings showing the lengths of femora,humeri,tibiae,fibulae,ulnae and radii length below the 5th percentile of corresponding gestational age.Karyotypes of the three fetuses were normal.SNP-array examination showed that each case had 1 to 2.5 Mb deletion in the pseudoautosomal region of the short arms of sex chromosomes,including SHOX gene.Their skeletal dysplasia were all caused by SHOX haploinsufficiency.Microdeletions of fetus 1 and 3 were inherited from their mothers,while that of fetus 2 was inherited from the father.After genetic counseling,two singleton gravidas decided to terminate their pregnancies and the twin pregnant one underwent selective reduction.Conclusion Prenatal ultrasound,in combination with SNP-array,offers fast and efficient detection of fetal skeletal dysplasia due to SHOX gene deficiency.