Overview
I'm working on a biology multi-part question and need the explanation and answer to help me learn.
A relatively new study has been published that looked at just how diverse the V, D, and J segments in the germline of T cell receptor genes are between people and populations. This diversity is even before somatic recombination… just the segments from which we have to choose when putting together a receptor. This paper suggests the the number of V, D, and J segements may be much higher than what is shown in the charts in our books and lecture. The findings were highlighted in a popular news piece - Major genetic study reveals unexpectedly high variation in T-cell receptor genes between persons, which cites the primary, peer reviewed article Archaic humans have contributed to large-scale variation in modern human T cell receptor genes
After reading the popular news piece and skimming the primary, peer reviewed article, please use what we have learned about T cell receptors to explain why we are just now learning about how variable the genes making up the TCR can be. You should imagine a fellow biology major who has NOT taken immunology is trying to understand why this is a surprise. They do not understand how immunologists hadn’t realized the variation, given that we have studied the T cell receptor proteins. Why wouldn’t studying the proteins actually show us what the variation in the germline genome is? They also ask why the genes cannot usually be detected by whole genome sequencing and what is so special about the B and T cell receptor gene segments that mean they required their own deep sequencing. Please answer the following questions in a way that they could understand. You can use biology terms, but should not expect them to be familiar with any of the immunological concepts we have covered.