Chapter 15, Problem 31ESP

Mutations in the IL2RG gene cause approximately 30 percent of severe combined immunodeficiency disorder (SCID) cases in humans. These mutations result in alterations to a protein component of cytokine receptors that are essential for proper development of the immune system. The IL2RG gene is composed of eight exons and contains upstream and downstream sequences that are necessary for proper transcription and translation. Below are some of the mutations observed. For each, explain its likely influence on the IL2RG gene product (assume its length to be 375 amino acids).

1. (a) Nonsense mutation in a coding region
2. (b) Insertion in Exon 1, causing frameshift
3. (c) Insertion in Exon 7, causing frameshift
4. (d) Missense mutation
5. (e) Deletion in Exon 2, causing frameshift
6. (f) Deletion in Exon 2, in frame
7. (g) Large deletion covering Exons 2 and 3