title: [Prenatal diagnosis of a case with 46,XX,del(4),dup(21)].
abstract: OBJECTIVE
  To investigate the genetic cause and prognosis of a fetus with a rare karyotype.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Center of Prenatal Diagnosis, Peking University People's Hospital, Beijing 100044, China. happyzh713@sina.com.
authors.forename: Lin
authors.initials: L
authors.lastname: Zhang
authors.forename: Meihong
authors.initials: M
authors.lastname: Ren
authors.forename: Guining
authors.initials: G
authors.lastname: Song
authors.forename: Xuexia
authors.initials: X
authors.lastname: Liu
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000025:Abortion, Eugenic; D000328:Adult; D002871:Chromosome Banding; D002872:Chromosome Deletion; D025063:Chromosome Disorders / Q000175:diagnosis / Q000235:genetics; D058674:Chromosome Duplication; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics*; D002894:Chromosomes, Human, Pair 4 / Q000235:genetics*; D056915:DNA Copy Number Variations; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis / Q000235:genetics; D005817:Genetic Counseling; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*