Practice question

Human globin loci are partitioned between chromosomes reflecting duplication history. Alpha-like cluster including embryonic zeta and adult alpha1 and alpha2 genes resides on short arm of chromosome 16 at 16p13.3 near telomere, within GC-rich isochore. Beta-like cluster spanning epsilon, G-gamma, A-gamma, delta and beta localizes to 11p15.5. Alpha cluster regulation involves major regulatory element HS-40 located upstream. Deletions or mutations in alpha cluster cause alpha-thalassemia with imbalanced globin chain synthesis. Comparative mapping demonstrates syntenic conservation of alpha locus across vertebrates, distinct from beta linkage.