Transmission of a ring chromosome 18 from a mother with 46,XX/47,XX, + r(18) mosaicism to her daughter, resulting in a 46,XX,r(18) karyotype.

Isolated skeletal malformations in a child with a small mosaic ring microduplication of 18 p11.21q11.2: Genotype–phenotype correlations

“…Reports of karyotypes involving pericentromeric region partial duplications, supernumerary markers, or supernumerary rings of chromosome 18 in the absence of other chromosomal anomalies are even scarcer in the literature [Callen et al, 1991; Jenderny et al, 1993; Timur et al, 2004]. Other than mild fullness of the left kidney, the patient did not have the same multisystem complications as the mos 47,XY,+r(18)[13]/46,XY[42] patient described in Timur et al [2004], such as dysmorphic features, limb hypertrophy, arteriovenous malformations, and a learning disability.…”

First familial case of ring chromosome 18 and monosomy 18 mosaicism

“…The proportion of all inherited ring chromosomes is stated to be no more than 1% of all ring chromosomes [Kosztolanyi et al, 1991]. Cases of vertical transmission of ring chromosome 18 from a mother to her offspring, like in our case, have already been described [Christensen et al, 1970;Donlan and Dolan, 1986;Fryns et al, 1992;Jenderny et al, 1993], while mosaicism monosomy 18 with familial ring chromosome 18 is more unusual. The ®rst cases of such monosomies 18 were initially considered as culture artifacts [Schinzel, 1984].…”

Familial ring (18) mosaicism in a 23‐year‐old young adult with 46,XY,r(18) (::p11→q21::)/46,XY karyotype, intellectual disability, motor retardation and single maxillary incisor and in his phenotypically normal mother, karyotype 47,XX,+r(18)(::p11→q21::)/46,XX

“…Ring chromosome 18 is not a rare cytogenetic finding, but familial transmission of ring chromosome 18 has been reported rarely [Kosztol anyi et al, 1991;Fryns et al 1992;Jenderny et al, 1993]; this only the second report of a supernumerary ring (18) in a parent and a ring (18) in the offspring [Jenderny et al, 1993]. The phenotypically and mentally normal mother had transmitted the ring chromosome 18 to her son.…”

“…Most likely the mosaicism in the mother originated from a rescue of a trisomic zygote generating normal diploid cell lines through mitotic non-disjunction events. The daughter described by Jenderny et al [1993] showed a 46,XX,r-(18) karyotype with a monocentric ring and the breakpoints approximately at p11 and q23 in all 100 lymphocytes studied. In contrast, the son in this report had a very interesting mosaicism of 46,XY,r(18) cells (37%, see FISH analysis section) and apparently normal cells (57%), which is unique compared to other reports on inherited ring chromosomes.…”

“…Accordingly, there have been exceptional reports of familial transmission of 18p and 18q deletions, in most cases from a mildly affected mother to her child [Velagaleti et al, 1996;Tsukahara et al, 2001;Chen et al, 2006;Linnankivi et al, 2006;Maranda et al, 2006]. In addition, there have been at least seven reports of familial transmission of ring chromosome 18 [Kosztol anyi et al, 1991;Fryns et al, 1992;Jenderny et al, 1993].…”