Cytogenetic study of a large cohort of patients with corpus callosum abnormalities

Hussen, Dalia F.; Kamel, Alaa K.; Mekkawy, Mona; Mohamed, Amal M.; Zaki, Maha S.; Issa, Mahmoud Y.; El Ruby, Mona O.; Ashaat, Engy A.; Ismail, Samira; Refaat, Khaled M.; Helmy, Nivine A.

doi:10.4103/MXE.MXE_7_20

Cytogenetic study of a large cohort of patients with corpus callosum abnormalities

Authors

Abstract

Introduction
Corpus callosum (CC) is the main fiber bundle connecting the brain interhemispheric white matter tracts. Abnormalities of CC may be isolated, or occur in association with other brain anomalies as a part of monogenic syndrome, with some inborn errors of metabolism or due to chromosomal abnormalities.
Aim
Detecting the prevalence and characteristics of chromosomal aberrations among patients with CC abnormalities in addition to determining the subsequent imperative diagnostic steps in order to reach a precise diagnosis.
Patients and methods
A total of 105 patients have been enrolled into this study. All patients were subjected to full history taking, thorough clinical examination, neuroimaging studies, psychological assessments, and cytogenetic studies including G-banding karyotyping and fluorescence in-situ hybridization analysis.
Results
The vast majority of the studied patients presented with developmental delay (74%). Intellectual disability was demonstrated in 50.4%. Dysmorphic features and microcephaly have been detected in 34% and 28%, respectively. According to MRI findings, the patients have been categorized into four groups: agenesis, hypoplasia, dysplasia, and dysplasia with hypoplasia of the CC. The category of hypoplasia of CC comprised 54.3% of the entire patients. Parental consanguinity was detected among 40% of the studied patients, suggesting the role of autosomal recessive genes. Cytogenetic abnormalities have been detected in 22% of the studied cases and parental chromosomal abnormalities have been detected in 13% of them.
Conclusion
Detailed cytogenetic analysis of patients with CC abnormalities as well as their parents is mandatory in the plan of diagnosis and for setting appropriate genetic counseling for families of these patients. The use of chromosomal microarray analysis is an essential future step to precisely characterize areas of chromosomal gains and losses in addition to the detection of novel copy number variants.

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