Related Experiment Video
Updated: Aug 2, 2026

Navigating MARRVEL, a Web-Based Tool that Integrates Human Genomics and Model Organism Genetics Information
Published on: August 15, 2019
Clinical variability in two pairs of identical twins with the Charcot-Marie-Tooth disease type 1A duplication
C A Garcia1, R E Malamut, J D England
1Department of Neurology, Louisiana State University Medical Center, New Orleans 70112-2822, USA.
Abstract:
We report two pairs of male homozygotic twins in two unrelated families with the Charcot-Marie-Tooth disease type 1A duplication. Homozygosity was supported by DNA analysis. There was remarkable congruity of conduction velocities between the left and right side of each twin and between twin brothers. The similarity and symmetry of the electrophysiologic deficit contrast with the variable and asymmetric clinical presentations. Variability of clinical expression in these patients with identical mutations suggests the action of stochastic factors or environmental modulation of disease severity.
Related Concept Videos
Pedigree Analysis
Multiple Allele Traits
Pleiotropy
Multiple Allele Traits
Gene Duplication and Divergence
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.
Comparing Copy Number Variations and SNPs
Copy number variations or CNVs are the structural variations that cover more than 1kb of DNA sequence. The single nucleotide polymorphism (SNP), on the other hand, is a single nucleotide change or a point mutation that is found in more than 1%...

