Fetal anomalies associated with an inversion duplication 13 chromosome.

We report the cytogenetics and pathology of a fetus with holoprosencephaly associated with an inversion duplication 13 chromosome. The pathology is compared with that found in cases of partial duplication (trisomy) and deficiency (monosomy) of chromosome 13 described in the literature. To our knowledge, this is the first time holoprosencephaly has been associated with this particular inversion duplication 13 chromosome. Careful pathology and complete chromosomal studies proved useful in counseling this couple.