Two cousins with partial trisomy 12q and monosomy 12p recombinants of a familial pericentric inversion of the chromosome 12

Abstract

Partial trisomy 12q and monosomy 12p lead to multiple malformation syndromes. Instead of trisomy 12q that has been reported as a clinically identifiable syndrome, monosomy 12p is characterized by a wide phenotypic spectrum. We report two cousins suffering from severe mental retardation, seizures, and dysmorphic features related to a trisomy 12q24.3-->qter and a monosomy 12p13-->pter resulting from a familial pericentric inversion of chromosome 12. In an attempt to improve the clinical delineation of these two syndromes, we compared our two patients with previous reports of these aneusomies. This review emphasizes the high frequency of familial translocations, including a breakpoint at 12q24 involved in trisomy 12q whereas monosomy 12p occurs most frequently de novo. Despite the poor specificity of the signs, this comparison allowed us to determine the clinical features present in more than 20% of patients with trisomy 12q or monosomy 12p. We particularly emphasize some consistent leading features of monosomy 12p, including microcephaly, dental, cardio-vascular, extremity, and sensorial abnormalities, initially not reported as recurrent in this syndrome.

De novo pure 12q22q24.33 duplication: First report of a case with mental retardation, ADHD, and Dandy‐Walker malformation

“…qter region, due to segregation of a parental balanced translocation [Lagier-Tourenne et al, 2004]. To our knowledge, only a few patients with pure 12q duplications have been described [Harrod et al, 1980;Ieshima et al, 1984;Dixon et al, 1993;Houfflin et al, 1993;El-Shanti et al, 1997;Ireland et al, 2004].…”

Sperm studies in heterozygote inversion carriers: a review

“…Many cases of recombinant progeny from pericentric inversion carriers have been reported in the literature (Ishii et al, 1997;Mejia-Baltodano et al, 1997;Goodman et al, 1999;Angle et al, 2000;Dufke et al, 2000;Ilgin Ruhi et al, 2001;Lazzaro et al, 2001;Battaglia et al, 2002;Garcia-Heras and Martin, 2002;Lagier-Tourenne et al, 2004). The viability of the recombinant products mostly depends on the genetic content (and so the size) of the noninverted segment because they are the potential regions to be deleted or duplicated by recombination.…”

A novel 2.3 Mb microduplication of 12q24.21q24.23 detected by genome-wide tiling-path resolution array comparative genomic hybridization in a girl with syndromic mental retardation

“…The current patient displayed eight of these 17 features. Lagier-Tourenne et al (2004) reported on two patients with monosomy 12p and trisomy 12q, who presented with ataxia. Interestingly, the spasticity, deafness and behavioural problems of our patient have not been described before in patients with a 12q duplication.…”