Prenatal diagnosis of a case with 46,XX,del(4),dup(21) / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the genetic cause and prognosis of a fetus with a rare karyotype.</p><p><b>METHODS</b>Fluorescence in situ hybridization (FISH) was used for verifying a structural chromosomal abnormality detected by conventional karyotyping analysis. Whole genome DNA microarray was used to analyze copy number variations carried by the fetus.</p><p><b>RESULTS</b>The fetus was found to have a 46,XX,dup(21)(?q21q22) karyotype, which was verified by FISH analysis as repetition of chromosome 21 region, namely nuc ish 21q22×3. Whole genome DNA microarray confirmed that there was a 17.87 Mb duplication in the 21q21.3q22.3 region, which involved GATA1, JAK2 and ALL genes and spanned the Down syndrome region. The genes are implicated in craniofacial abnormalities, cardiac abnormalities, mental retardation, growth retardation, limb abnormalities. In addition, there was also an 8.43 Mb deletion in the 4p16.1p16.3 region, which involved FGFR3, LETM1, WHSC1 and WHSC2 and other 64 OMIM genes and spanned the Wolf-Hirschhorn syndrome region. The genes are implicated in growth retardation, craniofacial abnormalities, cardiac abnormalities, mental retardation, and hypotonia. After consultation, the family chose to terminate the pregnancy at 25th week of gestation.</p><p><b>CONCLUSION</b>FISH can help to verify structural chromosome abnormalities suspected by conventional karyotyping analysis. Combined with whole genome microarray, these can determine copy number variation and its region containing the disease genes, and facilitate clinical analysis of the fetus.</p>

Genetic and prenatal diagnosis of a pregnant women with mental retardation / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To conduct genetic testing and prenatal diagnosis for a pregnant women with growth retardation, severe mental retardation, and a history of adverse pregnancies.</p><p><b>METHODS</b>G-banded chromosome analysis, fluorescence in situ hybridization (FISH), and whole genome DNA microarray were used to analyze the patient and her fetus.</p><p><b>RESULTS</b>The women was found to be a chimera containing two cell lines with 47 and 46 chromosomes, respectively. Both have involved deletion of 18q21.2q23. FISH analysis suggested that the cell line containing 47 chromosomes has harbored a chromosome marker derived from chromosome 15. The marker has contained chromosome 15p involving the SNRPN locus and part of 15q, which gave rise to a karyotype of 47,XX,del18q21.3,+ish mar D15Z1+ SNRPN+[82]/46,XX,del18q21.3[18]. Whole genome DNA microarray confirmed that a 3.044 Mb fragment from 15q11.2q12 was duplicated, which involved NIPA1, SNRPN and other 17 OMIM genes. Duplication of this region has been characterized by low mental retardation, autism, developmental delay. Meanwhile, there was a 17.992 Mb deletion at 18q21.33q23, which contained 39 OMIM genes including TNFRSF11A and PHLPP1. This fragment was characterized by mental retardation, developmental delay, short stature, and cleft palate. Whole genome microarray analysis confirmed that there was a 17.9 Mb deletion at 18q21.33q23, which has been implemented with mental retardation, general growth retardation, short stature, and cleft palate. After genetic counseling, the family decided to terminate the pregnancy at 21st week.</p><p><b>CONCLUSION</b>Combined chromosome karyotyping, FISH, and whole genome DNA microarray can determine the origin of marker chromosomes and facilitate delineation of its correlation with the clinical phenotype.</p>

Detection of a fetus with paternally derived 2q37.3 microdeletion and 20p13p12.2 microduplication using whole genome microarray technology / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To perform prenatal diagnosis for a fetus with multiple malformations.</p><p><b>METHODS</b>The fetus was subjected to routine karyotyping and whole genome microarray analysis. The parents were subjected to high-resolution chromosome analysis.</p><p><b>RESULTS</b>Fetal ultrasound at 28+4 weeks has indicated intrauterine growth restriction, left kidney agenesis, right kidney dysplasia, ventricular septal defect, and polyhydramnios. Chromosomal analysis showed that the fetus has a karyotype of 46,XY,der(2),der(20), t(2;20)(q37.3;p12.2), t(5;15) (q12.2;q25) pat. SNP array analysis confirmed that the fetus has a 5.283 Mb deletion at 2q37.3 and a 11.641 Mb duplication at 20p13p12.2. High-resolution chromosome analysis suggested that the father has a karyotype of 46,XY,t(2;20)(q37.3;p12.2),t(5;15)(q12.2;q25), while the mother has a normal karyotype.</p><p><b>CONCLUSION</b>The abnormal phenotype of the fetus may be attributed to a 2q37.3 microdeletion and a 20p13p12.2 microduplication. The father has carried a complex translocation involving four chromosomes. To increase the chance for successful pregnancy, genetic diagnosis and/or assisted reproductive technology are warranted.</p>