Difficulties of genetic counseling and prenatal diagnosis in a consanguineous couple segregating for the same translocation (14;15) (q11;q13) and at risk for Prader-Willi and Angelman syndromes

Eur J Hum Genet. 2004 Mar;12(3):181-6. doi: 10.1038/sj.ejhg.5201134.


Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are associated with a loss of function of imprinted genes in the 15q11-q13 region mostly due to deletions or uniparental disomies (UPD). These anomalies usually occur de novo with a very low recurrence risk. However, in rare cases, familial translocations are observed, giving rise to a high recurrence risk. We report on the difficulties of genetic counseling and prenatal diagnosis in a family segregating for a translocation (14;15)(q11;q13) where two consanguineous parents carry the same familial translocation in this chromosome 15 imprinting region. Both children of the couple inherited a chromosomal anomaly leading to PWS. However, a paternal 15q11-q13 deletion was responsible for PWS in the first child, whereas prenatal diagnosis demonstrated that PWS was associated with a maternal 15q11-q13 UPD in the fetus. This report demonstrates that both conventional and molecular cytogenetic parental analyses have to be performed when a deletion is responsible for PWS or AS in order not to overlook a familial translocation and to insure reliable diagnosis and genetic counseling.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angelman Syndrome / diagnosis
  • Angelman Syndrome / genetics*
  • Chromosome Deletion
  • Chromosomes, Human, Pair 14 / genetics*
  • Chromosomes, Human, Pair 15 / genetics*
  • Consanguinity
  • Female
  • Genetic Counseling*
  • Humans
  • Karyotyping
  • Male
  • Pedigree
  • Prader-Willi Syndrome / diagnosis
  • Prader-Willi Syndrome / genetics*
  • Pregnancy
  • Prenatal Diagnosis*
  • Translocation, Genetic / genetics*