Identification of a novel recessive RELN mutation using a homozygous balanced reciprocal translocation

Maha Zaki, Marwa Shehab, Alice Abd El-Aleem, Ghada Abdel-Salam, Hajira B. Koeller, Yesim Ilkin, M. Elizabeth Ross, William B. Dobyns, Joseph G. Gleeson

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66 Scopus citations


Two siblings from a consanguineous Egyptian marriage showed an identical phenotype of cortical lissencephaly with cerebellar hypoplasia, severe epilepsy, and mental retardation. Examination of karyotype revealed 46, t(7;12) (q22;p13)mat (7;12)(q22;p13)pat in both affected children, suggesting a homozygous reciprocal balanced translocation. Each healthy parent was a carrier of the balanced translocation in the heterozygous state, suggesting homozygous disruption of a gene involved in brain development. There were early spontaneous abortions in this family, as would be expected from transmission of an unbalanced chromosome. A disruption of RELN at 7q22.1 with absence of encoded protein was identified. This is the first demonstration that such rare homozygous translocations can be used to identify recessive disease gene mutations.

Original languageEnglish (US)
Pages (from-to)939-944
Number of pages6
JournalAmerican Journal of Medical Genetics, Part A
Issue number9
StatePublished - May 1 2007
Externally publishedYes


  • Balanced translocation
  • Consanguinity
  • Homozygous
  • Lissencephaly
  • Reelin


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