Francisco Flores-Ramírez1, Claudia Palacios-Guerrero2, Constanza García-Delgado1, Ariadna Berenice Morales-Jiménez1, Christian Martín Arias-Villegas1, Alicia Cervantes3, Verónica Fabiola Morán-Barroso4. 1. Departamento de Genética, Hospital Infantil de México Federico Gómez, México, D.F., México. 2. Departamento de Genética, Hospital Infantil de México Federico Gómez, México, D.F., México; Servicio de Genética, Hospital General de México Dr. Eduardo Liceaga, Facultad de Medicina, UNAM, México, D.F., México. 3. Servicio de Genética, Hospital General de México Dr. Eduardo Liceaga, Facultad de Medicina, UNAM, México, D.F., México. 4. Departamento de Genética, Hospital Infantil de México Federico Gómez, México, D.F., México. Electronic address: vfmoran@himfg.edu.mx.
Abstract
BACKGROUND AND AIMS: Trisomy 21 is the most frequent genetic cause of intellectual disability. It is caused by different cytogenetic aberrations: free trisomy, Robertsonian translocations, mosaicism, duplication of the critical region and other structural rearrangements of chromosome 21. The aim of the study was to identify in Mexican trisomy 21 patients who attended Hospital Infantil de México Federico Gómez from 1992-2011 the type and frequency of the cytogenetic aberration and to evaluate the effect of maternal age. METHODS: A retrospective analysis of epidemiological data and karyotype reports were carried out; type and frequency of the cytogenetic variants were determined. RESULTS: We identified 2,018 cases referred with a clinical diagnosis of trisomy 21. In 1,921 analyses (95.2%) a cytogenetic variant of trisomy 21 was identified: free trisomy 21 in 1,787 cases (93.02%), four cases (0.21%) had an additional non-contributory aberration; Robertsonian translocations in 92 cases (4.79%); mosaicism in 31 cases (1.61%) and seven cases (0.36%) had other chromosomal abnormalities, five (0.26%) had other contributory structural rearrangements and two corresponded to double aneuploidies (0.10%). Gender distribution was 1,048 (54.56%) males and 873 (45.44%) females. A maternal age effect was observed in patients with free trisomy 21 with mothers >36 years of age. CONCLUSION: The present work reports the experience of a Mexican referral center regarding the karyotype diagnosis of patients with trisomy 21 and is one of the most extensive studies published so far. Percentages of the cytogenetic abnormalities present in our population reflect the ones previously reported for these cytogenetic alterations worldwide.
BACKGROUND AND AIMS: Trisomy 21 is the most frequent genetic cause of intellectual disability. It is caused by different cytogenetic aberrations: free trisomy, Robertsonian translocations, mosaicism, duplication of the critical region and other structural rearrangements of chromosome 21. The aim of the study was to identify in Mexican trisomy 21 patients who attended Hospital Infantil de México Federico Gómez from 1992-2011 the type and frequency of the cytogenetic aberration and to evaluate the effect of maternal age. METHODS: A retrospective analysis of epidemiological data and karyotype reports were carried out; type and frequency of the cytogenetic variants were determined. RESULTS: We identified 2,018 cases referred with a clinical diagnosis of trisomy 21. In 1,921 analyses (95.2%) a cytogenetic variant of trisomy 21 was identified: free trisomy 21 in 1,787 cases (93.02%), four cases (0.21%) had an additional non-contributory aberration; Robertsonian translocations in 92 cases (4.79%); mosaicism in 31 cases (1.61%) and seven cases (0.36%) had other chromosomal abnormalities, five (0.26%) had other contributory structural rearrangements and two corresponded to double aneuploidies (0.10%). Gender distribution was 1,048 (54.56%) males and 873 (45.44%) females. A maternal age effect was observed in patients with free trisomy 21 with mothers >36 years of age. CONCLUSION: The present work reports the experience of a Mexican referral center regarding the karyotype diagnosis of patients with trisomy 21 and is one of the most extensive studies published so far. Percentages of the cytogenetic abnormalities present in our population reflect the ones previously reported for these cytogenetic alterations worldwide.
Authors: Mariana Rabello Laignier; Luís Carlos Lopes-Júnior; Raquel Esperidon Santana; Franciéle Marabotti Costa Leite; Carolina Laura Brancato Journal: Int J Environ Res Public Health Date: 2021-11-14 Impact factor: 3.390
Authors: Annette Karmiloff-Smith; Tamara Al-Janabi; Hana D'Souza; Jurgen Groet; Esha Massand; Kin Mok; Carla Startin; Elizabeth Fisher; John Hardy; Dean Nizetic; Victor Tybulewicz; Andre Strydom Journal: F1000Res Date: 2016-03-23