NORMAL PHENOTYPE WITH MATERNAL ISODISOMY IN A FEMALE WITH 2 ISOCHROMOSOMES - I(2P) AND I(2Q)

A 36-year-old normal healthy female was karyotyped because all of her five pregnancies had terminated in spontaneous abortions during the fi rst 3 mo. Cytogenetic investigation disclosed a female karyotype with isochromosomes of 2p and 2q replacing the two normal chromosomes 2. He r husband and both of her parents had normal karyotypes. Molecular stu dies revealed maternal only inheritance for chromosome 2 markers. Redu ction to homozygosity of all informative markers indicated that the is ochromosomes derived from a single maternal chromosome 2. Except for t he possibility of homozygosity for recessive mutations, maternal unipa rental disomy 2 appears to have no adverse impact on the phenotype. Ou r data indicate that no maternally imprinted genes with major effect m ap to chromosome 2.