Molecular cytogenetic characterization of marker chromosomes found at prenatal diagnosis

Abstract

The nature and origin of two de novo small marker chromosomes found at prenatal diagnosis were determined by fluorescence in situ hybridization using chromosome centromere-specific probes and chromosome-specific plasmid libraries. One marker was found in a mosaic state and was shown to be an i(18p). The second marker was characterized as an inv dup(22). We conclude that molecular cytogenetic analysis contributes to the identification of marker chromosomes and therefore facilitates genetic counselling and decision-making for the parents.

De novo isochromosome 18p in two patients: cytogenetic diagnosis and confirmation by chromosome painting

“…Mosaicism of i(18p) has been reported in four further cases (Fryns et al 1985, Gocke et al 1986, Plattner et al 1993a, and Verschraegen-Spae et al 1993), but was not present in our patients.…”

Prenatal diagnosis of mosaicism for tetrasomy 18p: cytogenetic, FISH and morphological findings

“…Although a distinct syndrome associated with tetrasomy 18p has been well documented postnatally, prenatal diagnosis of this condition, particularly in the mosaic form, is seldom reported (Gö cke et al, 1986;Verschraegen-Spae et al, 1993;Blennow et al, 1994). We describe what we believe to be the second case of mosaicism for tetrasomy 18p in a fetus, associated with anomalies at autopsy.…”

Tetrasomy 18p: Report of the molecular and clinical findings of 43 individuals

“…Reports of mosaic tetrasomy 18p in the literature are uncommon. There are several reports of a prenatal diagnosis of mosaic tetrasomy 18p followed by termination of the pregnancy [Gocke et al, 1986; Verschraegen‐Spae et al, 1993; Blennow et al, 1995; Pinto et al, 1998]. Thus, these reports do not provide useful information regarding the clinical features of individuals with mosaic tetrasomy 18p.…”