Potential biological significance of mutations

B.1.1.7 lineage. This variant has 17 mutations (the 14 amino acid replacements and 3 in-frame deletions
are listed in Table 1b). Two of these mutations have already been described to alter SARS-CoV-2 biology:
N501Y sits in the receptor binding motif (RBM) of the Spike protein, and has been described to increase
binding affinity to the human ACE-2 receptor; 69-70del has been identified in variants associated with
immune escape in immunocompromised patients and is responsible for a “dropout” in the S gene PCR
target in certain diagnostic tests (e.g. Thermo Fisher TaqPath). These tests target multiple regions of the
virus genome, so the test itself is not compromised. Reported cases and phylogenetic analyses have
indicated an exceptional rate of introduction of mutations into this lineage. It has been hypothesised that
this lineage may have resulted from the transmission of the virus from a chronically-infected individual.
This is based on observations that a high rate of mutations may accumulate In immunocompromised
patients with chronic infections of SARS-COV-2.

https://www.cogconsortium.uk/wp-content/uploads/2020/12/Report-1_COG-UK_19-December-2020_SARS-CoV-2-Mutations.pdf