Misconceptions about mosaicism

✍ Scribed by D. K. Kalousek; I. J. Barrett; V. S. Lestou

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 26 KB
• Volume: 17
• Category: Article
• ISSN: 0197-3851
• DOI: 10.1002/(sici)1097-0223(199709)17:9<888::aid-pd1166>3.0.co;2-f

✦ Synopsis

limits and after birth no external defect was seen. Unfortunately, X-ray examination of the fetal spine was not performed and therefore the ultrasonographic suspicion of spina bifida (occulta) was not confirmed.

An interesting cytogenetic difference between the two cases is worth mentioning; the cytotrophoblast cells of the published case had a normal karyotype, but in our case they showed a mosaic 46,XX,inv dup(18p)[8]/46,XX [4]. However, after birth, the placentae were not investigated. It is clear that studying the chromosomes of only one biopsy does not permit a definite conclusion and can never exclude the possibility of placental mosaicism (Henderson et al., 1996).

We think that the findings in our fetus further support the supposition of the presence of candidate gene(s) on chromosome 18 for cleavage of the brain (Overhauser et al., 1993).

We are planning additional cytogenetic and molecular studies to investigate a possibly common origin or a single event leading to the dup(18p) in the cytotrophoblast and the i(18q) in the fetus.