Prenatal diagnosis of complete paternal uniparental isodisomy for chromosome 3: a case report

BACKGROUND: Uniparental disomy (UPD) is defined as an inheritance of two chromosomes from only one of the parents with no representative copy from the other. Paternal-origin UPD of chromosome 3 is a very rare condition, with only five cases of paternal UPD(3) reported. CASE PRESENTATION: Here, we report a prenatal case that is only the second confirmed paternal UPD(3) reported with no apparent disease phenotype. The fetus had a normal karyotype and normal ultrasound features throughout gestation. Copy neutral regions of homozygosity on chromosome 3 were identified by single nucleotide polymorphism (SNP) array. Subsequent SNP array data of parent–child trios showed that the fetus carried complete paternal uniparental isodisomy (isoUPD) of chromosome 3. The parents decided to continue with the pregnancy after genetic counseling, and the neonate had normal physical findings at birth and showed normal development after 1.5 years. CONCLUSIONS: These findings provided further evidence to confirm that there were no important imprinted genes on paternal chromosome 3 that caused serious diseases and a reference for the prenatal diagnosis and genetic counseling of UPD(3) in the future.