Figure 16.2. Deletions of α-globin genes in α-thalassemia.

Figure 16.2Deletions of α-globin genes in α-thalassemia

Normal copies of chromosome 16 carry two active α-globin genes and an inactive pseudogene arranged in tandem. Repeat blocks (labeled X and Z) may misalign, allowing unequal crossover. The diagram shows unequal crossover between mis-aligned Z repeats producing a chromosome carrying only one active α gene. Unequal crossovers between X repeats have a similar effect. Unequal crossovers between other repeats (not shown) can produce chromosomes carrying no functional α gene. Individuals may thus have any number from 0 to 4 or more α-globin genes. The consequences become more severe as the number of α genes diminishes. See Weatherall et al., 1995 for detail.

From: Chapter 16, Molecular pathology

Cover of Human Molecular Genetics
Human Molecular Genetics. 2nd edition.
Strachan T, Read AP.
New York: Wiley-Liss; 1999.
Copyright © 1999, Garland Science.

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.