Learning the statistics and landscape of somatic mutation-induced insertions and deletions in antibodies

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Hauptverfasser: Lupo, Cosimo, Spisak, Natanael, Walczak, Aleksandra M., Mora, Thierry
Format: Preprint
Veröffentlicht: 2021
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author Lupo, Cosimo
Spisak, Natanael
Walczak, Aleksandra M.
Mora, Thierry
author_facet Lupo, Cosimo
Spisak, Natanael
Walczak, Aleksandra M.
Mora, Thierry
contents Affinity maturation is crucial for improving the binding affinity of antibodies to antigens. This process is mainly driven by point substitutions caused by somatic hypermutations of the immunoglobulin gene. It also includes deletions and insertions of genomic material known as indels. While the landscape of point substitutions has been extensively studied, a detailed statistical description of indels is still lacking. Here we present a probabilistic inference tool to learn the statistics of indels from repertoire sequencing data, which overcomes the pitfalls and biases of standard annotation methods. The model includes antibody-specific maturation ages to account for variable mutational loads in the repertoire. After validation on synthetic data, we applied our tool to a large dataset of human immunoglobulin heavy chains. The inferred model allows us to identify universal statistical features of indels in heavy chains. We report distinct insertion and deletion hotspots, and show that the distribution of lengths of indels follows a geometric distribution, which puts constraints on future mechanistic models of the hypermutation process.
format Preprint
id arxiv_https___arxiv_org_abs_2112_07953
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Learning the statistics and landscape of somatic mutation-induced insertions and deletions in antibodies
Lupo, Cosimo
Spisak, Natanael
Walczak, Aleksandra M.
Mora, Thierry
Genomics
Affinity maturation is crucial for improving the binding affinity of antibodies to antigens. This process is mainly driven by point substitutions caused by somatic hypermutations of the immunoglobulin gene. It also includes deletions and insertions of genomic material known as indels. While the landscape of point substitutions has been extensively studied, a detailed statistical description of indels is still lacking. Here we present a probabilistic inference tool to learn the statistics of indels from repertoire sequencing data, which overcomes the pitfalls and biases of standard annotation methods. The model includes antibody-specific maturation ages to account for variable mutational loads in the repertoire. After validation on synthetic data, we applied our tool to a large dataset of human immunoglobulin heavy chains. The inferred model allows us to identify universal statistical features of indels in heavy chains. We report distinct insertion and deletion hotspots, and show that the distribution of lengths of indels follows a geometric distribution, which puts constraints on future mechanistic models of the hypermutation process.
title Learning the statistics and landscape of somatic mutation-induced insertions and deletions in antibodies
topic Genomics
url https://arxiv.org/abs/2112.07953