A Down syndrome female infant with partial trisomy of chromosome 21--abnormal nuchal translucency screening test.

We describe a case of 24-year-old mother with abnormal nuchal translucency screening test. Standard G banding of chromosomes showed a normal prenatal karyotype. A Down syndrome female infant with partial duplication of the long arm of chromosome 21 was born resulted from a maternal pericentric inversion of region p1.1 to q22.1 of one of chromosome 21. As far as we know this case reports the first abnormal nuchal translucency screening test result due to partial trisomy of chromosome 21.