Cytogenetic and Clinical Features in Children Suspected With Congenital Abnormalities in 1 Medical Center of Zhejiang Province From 2011 to 2014

First report on chromosomal abnormalities in Eastern Morocco: Identification of a new case of a de novo partial trisomy 13q using single-nucleotide polymorphism array

BACKGROUND

Chromosomal abnormalities are the main cause of birth defects, intellectual disability, and miscarriages. They contribute to significant human morbidity and infant mortality. Here we report for the first time the chromosomal abnormalities encountered in the population of Eastern Morocco. Furthermore, we describe a new case of a de novo partial trisomy 13q combined with a terminal deletion in an 11-day-old girl.

METHODS

From November 2015 to March 2022, 195 patients from the BRO Biobank who were clinically suspected of having chromosomal abnormalities were referred to the cytogenetics laboratory of the Genetics Unit of the Faculty of Medicine and Pharmacy of Oujda for cytogenetic study. Karyotyping analysis was performed on peripheral blood samples using standard R banding techniques. To identify single-nucleotide polymorphism (SNP) and copy number variants (CNVs), Illumina SNP array was used.

RESULTS

Among 195 studied cases, 32 (16.4 %) had abnormal karyotypes, of which 12 cases had numerical aberrations while 20 cases had structural aberrations. The most common numerical aberrations were Turner syndrome and Down syndrome followed by Edward, Patau, and Klinefelter syndromes. For structural aberrations, translocations were the most common, followed by derivative chromosomes, inversions, deletions, and an addition on chromosome 13 identified in an 11-day-old girl. To further characterize this addition, SNP array was carried out and revealed a 58.8-Mb duplication in region 13q14.3q34 associated with a 1-Mb deletion in region 13q34. Follow-up parental chromosomes analysis showed normal karyotypes for the parents, confirming that this partial trisomy 13q was de novo. Comparison of the phenotype associated with this novel duplication on chromosome 13q with those previously reported confirmed the considerable variability in the phenotype of the patients with partial trisomy 13q.

CONCLUSION

This study provided the first report on chromosomal abnormalities in Eastern Morocco and it enriched the phenotype spectrum of partial trisomy 13q and further confirmed the genotype-phenotype correlations. Furthermore, these findings justify the need to set up microarray comparative genomic hybridization techniques in Morocco for better genetic diagnosis.

Chromosomal abnormalities: subgroup analysis by maternal age and perinatal features in zhejiang province of China, 2011-2015

BACKGROUND

Recently, the prevalence of chromosomal abnormalities (CA) increased as the increasing proportion of mothers with advanced age. We aimed to explore the prevalence of CA in relation to maternal age and perinatal features.

METHODS

A retrospective study was performed based on provincial birth defects surveillance data. The relative risk (RR) and 95% confidence interval (CI) were used to calculate maternal age-specific rates of CA. Socio-demographic characteristics of mothers and perinatal features were listed.

RESULTS

The total prevalence of CA was 6.38 per 10,000 births, which increased per 10,000 births linearly from 4.02 in 2011 to 9.13 in 2015 (x ²_line-trend =52.69, p < 0.001). During this period, the prevalence for CA per 10,000 births among women over 35 years old increased from 15.34 in 2011 to 33.82 in 2015 (x ²_line-trend =115121.6, p < 0.001). The RR for overall CA, trisomy 21(T21), trisomy 18(T18) and others in mothers 35 years or older were 6.64 (95% CI 5.55 ~ 7.93), 6.83 (95% CI 5.63 ~ 8.30), 4.06 (95% CI 2.09 ~ 7.90) and 7.54 (95% CI 4.02 ~ 14.11) respectively in comparison to mothers aged 25-29 years old. The stillbirths rate for total CA was 76.45%. T21 and T18 were strongly associated with multiple anomalies, especially congenital heart abnormalities.

CONCLUSIONS

The prevalence of CA increased as maternal age increased. Cases with CA were associated with other congenital defects and high mortality risk.

Cytogenetic Analysis for Suspected Chromosomal Abnormalities; A Five Years Experience

INTRODUCTION

Chromosomal abnormalities are the results of alterations in the number or structure of chromosomes causing significant human morbidity and mortality. They are responsible for a large proportion of miscarriages, developmental delay, disorders of sexual development, congenital malformations and mental retardation.

AIM

The aim of this study was to describe the prevalence of different chromosomal abnormalities in North Indian patients referred for cytogenetic analysis.

MATERIALS AND METHODS

Total of 859 patients ranging from newborn to 37 years of age were referred to the division of genetics, Department of Paediatrics between 2010 and 2015, with a variety of clinical disorders; Down syndrome (DS), Turner's syndrome (TS) and Klinefelter syndrome; amenorrhea; ambiguous sex and multiple congenital malformations. Chromosomal analysis was performed on lymphocyte culture according to standard methods.

RESULTS

Of the 859 cases studied, 371 (43.1%) had chromosomal abnormalities. The most common autosomal abnormalities were DS 302 (81.4%) and sex chromosomal abnormalities were TS 51 (13.7%). Numerical abnormalities were accounted for 353 (41.0%) and structural abnormalities 18 (2.0%), respectively. Various other chromosomal anomalies were also reported.

CONCLUSION

We have reviewed the incidence and distribution of chromosomal abnormalities and found higher rate of chromosomal abnormalities 43.1% in the referred cases. Our data suggest that chromosomal analysis is important tool in the evaluation of genetic disorders and helps clinicians to provide accurate diagnosis and proper genetic counselling.