20 p duplication as a result of parental translocation: familial case report and a contribution to the clinical delineation of the syndrome

Abstract

We report two related patients, presenting duplication 20p, with a characteristic phenotype including normal growth pattern, mental and psycho‐motor retardation, reduced motor coordination, poor language development, round face and prominent cheeks, vertebral and dental anomalies, and renal malformations. Familial chromosome analysis showed a balanced translocation t(20;21)(pll;q22) in three members of the family. These cases, together with those previously reported in the literature, allow us to make a better delineation of the duplication 20p syndrome, identifying more clearly the symptoms that must be considered as characteristic of this clinical picture.

Molecular cytogenetic characterization of the first reported case of inv dup del 20p compatible with a U‐type exchange model

“…Thirty-nine cases have been reported, all but two cases [Zumel et al, 1989;Molina-Gomes et al, 2006] diagnosed postnatally. Most partial trisomies result from reciprocal translocation [Taylor et al, 1976;Marcus et al, 1979;Funderburk et al, 1983;Lurie et al, 1985;Vamos et al, 1985;Zumel et al, 1989;Grammatico et al, 1992;LeChien et al, 1994;Belin et al, 1999;Oppenheimer et al, 2000;Wieczorek et al, 2003;Thomas et al, 2004;T€ umer et al, 2005;Brenk et al, 2007]. In a few cases, trisomy 20p results from parental inversion [Lucas et al, 1985;Bown et al, 1986;Molina-Gomes et al, 2006;Chaabouni et al, 2007] or the formation of isochromosomes [Sidwell et al, 2000].…”

“…Grammatico et al [1992] reported eight typical features associated with trisomy of 20p (frequency 67-96%): mental retardation, psychomotor acquisition delay, normal growth, round face with prominent cheeks, dental abnormalities, vertebral abnormalities, poor motor coordination and poor speech. Oppenheimer added new phenotypic elements to this list in 2000, mostly relating to dysmorphic features, with a frequency of 34-54%.…”

Molecular Characterization of a Familial 13.6-Mb 20p11.1p12.1 Duplication without Clinical Consequence

“…Trisomy 20p in combination with another chromosomal imbalance has been reported in approximately 40 patients; these showed intellectual disability, poor motor coordination, delayed speech and language development, abnormalities of the skeletal system, congenital heart defects, and dysmorphic features including a round face with full cheeks, highly arched eyebrows, upslanting palpebral fissures, abnormal ears, and abnormalities of the teeth [Bown et al, 1986;Grammatico et al, 1992;Oppenheimer et al, 2000;Sidwell et al, 2000;Chaabouni et al, 2007;Bartolini et al, 2013]. Most patients carried unbalanced translocations resulting in trisomy 20p and monosomy of another chromosomal fragment.…”

“…Partial trisomy 20p is a rare chromosomal aberration that in most cases is due to a parental translocation [Grammatico et al, 1992;Oppenheimer et al, 2000] or inversion [Bown et al, 1986;Kang et al, 2012], but can also occur de novo [Faivre et al, 2000;Bartolini et al, 2013]. In most cases, the patient carries an unbalanced translocation leading to partial trisomy 20p and monosomy of another chromosome.…”

“…Trisomy 20p has been reported in approximately 40 patients [Bown et al, 1986;Grammatico et al, 1992;Faivre et al, 2000;Oppenheimer et al, 2000;Sidwell et al, 2000;Chaabouni et al, 2007;Bartolini et al, 2013] who share the following characteristics: intellectual disability, poor motor coordination, delayed speech and language development, abnormalities of the skeletal system, congenital heart defects, and dysmorphic features. Partial trisomy 20p is a rare chromosomal aberration that in most cases is due to a parental translocation [Grammatico et al, 1992;Oppenheimer et al, 2000] or inversion [Bown et al, 1986;Kang et al, 2012], but can also occur de novo [Faivre et al, 2000;Bartolini et al, 2013].…”