Isochromosome 1q as the sole chromosomal abnormality in two fetal teratomas - Possible trisomic or tetrasomic zygote rescue in fetal teratoma with anadditional isochromosome 1q

An isochromosome of the long arm of chromosome 1 leading to tetrasomy 1q wa s detected as the sole chromosomal aberration in two cases of fetal teratom a arising from the oral cavity. This type Of teratoma is extremely rare and has seldom been investigated cytogenetically. Studies of DNA markers in th e tumor, normal fetal skin, and parental cells demonstrated that in both ca ses the additionl 1q material was of maternal origin. In one of the patient s, the teratoma had maternal 1q marker alleles that were not found in the f etal body cells. This implies that the tumor was nor derived in a direct wa y from the fetal body tissue; instead, the chromosomally-normal fetus might be the result of some trisomic or tetrasomic zygote rescue mechanism. (C) Elsevier Science Inc., 1999. All rights reserved.