Genetic analysis of a pedigree with atypical partial 4q trisomy

OBJECTIVE To explore the genetic basis for a Chinese pedigree affected with mental retardation. METHODS G-banded karyotyping analysis and single nucleotide polymorphism microarray (SNP array) were used to detect the genetic variants within the family, and the origin of the variants was analyzed using UPDtool Statistics software. RESULTS The patient, a 26-year-old female, was found to have a chromosomal karyotype of 46,XX,dup(4)(q28.2q31.3),and SNP array revealed a 25.71 Mb duplication at 4q28.2-q31.3. The duplication was inherited from her father, and her fetus was found to carry the same duplication. CONCLUSION The duplication of the patient probably underlay the mental retardation. The gender of the carrier and parental origin of the duplication might have led to the variation in their clinical phenotype.