Inv dup (15): Prenatal diagnosis and postnatal follow‐up

Abstract

A de novo inv dup (15) was diagnosed at amniocentesis. No physical abnormalities were detected after birth. The boy developed severe mental and motor retardation, which became obvious at 16 months of age.

Inv dup(15) supernumerary marker chromosomes.

“…At 16 months, the child had severe mental and motor retardation. 25 In other cases where the marker was both small and metacentric, no phenotypic effect was exerted, but still others resulted in a termination of pregnancy even when the marker had been familially inherited, reflecting the uncertainty associated with prenatal marker detection. It would seem that despite the relationship between marker size and phenotype, the finding of a marker prenatally causes diagnostic dilemmas.…”

“…Of the six which continued, two markers were also familial, but in neither case was the outcome described, and a third baby with a de novo "G like" inv dup(15) marker was severely retarded. 25 The final three were apparently normal, but of these one also inherited the marker from the mother and in a second it was present only in mosaic form.30 This latter baby was developmentally normal at 21 years of age32 but it would be interesting to learn of the later development of the other four babies (table 1 1).…”

Partial hexasomy 15pter->15q13 including SNRPN and D15S10: first molecular cytogenetically proven case report

“…The presence of such chromosomes is usually associated with mental retardation, developmental delay, epilepsy, and behavioural problems like autism. 3 It is possible that the clinical severity depends on the size of the SMC and its euchromatic material, for example, almost no clinical signs were detectable in a case with idic(15)(pter→q12), 4 while a severe phenotype including all typical clinical signs was present in a patient with the karyotype 47,+idic(15)(pter→q13). 3 5 6 However, there are also reports which show an inconsistent relationship between marker size, gene dosage, and severity of the phenotype.…”

Parental age, and how extra isochromosomes (secondary trisomy) arise

“…Likewise, for dicentric secondary trisomy, both maternal and paternal ages were significantly greater than 27 and 29,.respectively (P< <0.0001 for both). Gocke et al 1986, Miny et al 1986, Van Dyke 1987 Cross in press). The variable degree of mosaicism among tissues in secondary trisomies will cause diagnostic problems for the prenatal geneticists.…”