Paternal meiotic origin of der(21;21)(q10;q10) mosaicism [46,XX/46,XX,der(21;21)(q10;q10),+21] in a girl with mild Down syndrome

Abstract

Mosaicism for a derivative 21, der(21;21)(q10;q10), is a rare chromosomal abnormality. Since a normal cell line is present, mitotic origin is considered. Chromosome examination of a female with developmental delay and dysmorphic features compatible with mosaic trisomy 21 revealed a normal cell line and a second cell line with a der(21;21)(q10;q10) [46,XX/46,XX,der(21;21)(q10;q10), + 21]. Molecular investigation with a panel of highly polymorphic microsatellites mapping to chromosome 21 demonstrated three different alleles, two of paternal and one of maternal origin. Therefore, either formation of the der(21;21)(q10;q10) during paternal meiosis with subsequent loss of the der(21;21)(q10;q10) and mitotic reduplication of the maternal homologue in the normal cell line, or more likely a zygote with paternally derived trisomy 21 and subsequent mitotic formation of the der(21;21)(q10;q10) have to be considered. This case again shows that mammalian chromosome aberrations may have a more complex mechanism of formation than was previously thought.

Paternal origin of der(X)t(X;6) in a girl with trisomy 6p and unbalanced t(6;10) mosaicism in her mother

“…The prevalence of this type of chromosomal anomaly is unknown since low level mosaicisms are easily missed. The unusual unbalanced translocation mosaicism detected in this study is uncommon and has not been reported yet [Cohen et al, 1983; Aurias and Dutrillaux, 1986; Farrell, 1991; Petković et al, 1992; Pettenati et al, 1993; Kotzot and Schinzel, 2000]. There are at least two different modes of origin.…”

Heat and humidity performance of injection molded PLA for durable applications

“…In mosaic carriers of Rob/iso carriers detected postnatally (Table III), there is an expected prevalence of rearrangement of chromosome 21 because of the increased survival of individuals with trisomy 21 compared to carriers of trisomy for 13–15 and 22. Although some structural aberrations may have meiotic origin [Kotzot and Schinzel, 2000], formation of mosaicism requires postzygotic events. In this group (Rob/iso carriers) there is a female prevalence (seven males and 12 females), but the difference from the expected sex ratio of 1.06 in the newborn population does not reach statistical significance ( P = 0.2163).…”

Mosaicism del(8p)/inv dup(8p) in a dysmorphic female infant: a mosaic formed by a meiotic error at the 8p OR gene and an independent terminal deletion event

“…Possibly because of this assumption, the origin of the rearrangement has only been investigated in seven reports and in none do the two cell lines carry different aberrant chromosomes. [19][20][21][22][23][24][25] In three reports a meiotic error occurred first, followed by either a loss or a rearrangement of the trisomic chromosome. 19 22 24 The finding in this patient reinforces the idea that many chromosomal rearrangements occurring in mosaic people may have their origin during meiosis.…”