IBD Sharing Bands

Classify measured IBD sharing by caller-defined bands without assigning a unique pedigree relationship.

Description

Identity-by-descent sharing can be summarized by total centimorgans.

Identity-by-descent sharing can be summarized by total centimorgans. Overlapping relationship distributions make descriptive bands more appropriate than a unique pedigree label.

Classify measured IBD sharing by caller-defined bands without assigning a unique pedigree relationship.

When to use IBD Sharing Bands

Use this for the following task: Classify measured IBD sharing by caller-defined bands without assigning a unique pedigree relationship.

Prepare the observed records or explicit model parameters requested below. Keep probabilities as fractions and paired records aligned.

How to use IBD Sharing Bands and understand its results

Prepare the observed records or explicit model parameters requested below. Keep probabilities as fractions and paired records aligned.
Enter sharedSegmentsCm, totalDiploidMapCm, bandLabels, minimumSharedCm using the field table, then run the tool.
Read totalSharedCm, sharedMapFraction, sharingBand. Interpret flags, units, ordering and placeholder values using the rules below.
Review any reported issue or failed check, correct the supplied values when appropriate, and verify the result in its intended context.

Input field	Meaning	Value type and bounds	Requirement
sharedSegmentsCm	Shared segments cm	list of number; each entry: number	Required
totalDiploidMapCm	Sum of both homologous genetic-map lengths. Segment lengths must count shared homologues consistently and exclude overlapping duplicates.	number	Required
bandLabels	Band labels	list of string; each entry: string	Required
minimumSharedCm	Minimum shared cm	list of number; each entry: number	Required

Sum nonnegative segment lengths without exceeding the positive supplied map length. Use aligned strictly increasing nonnegative cutoffs and return below-bands when none is reached.^[1]

sharedFraction = ΣsegmentCm/totalDiploidMapCm; band = highest cutoff reached

This summarizes the declared operation. Units, indexing, inclusivity and exceptional cases are explained in the surrounding text.

Output field	Meaning	Value type
totalSharedCm	Total shared cm	number
sharedMapFraction	Shared map fraction	number
sharingBand	Sharing band	string

json

{
  "input": {
    "sharedSegmentsCm": [
      100,
      150
    ],
    "totalDiploidMapCm": 500,
    "bandLabels": [
      "low",
      "high"
    ],
    "minimumSharedCm": [
      0,
      200
    ]
  },
  "output": {
    "totalSharedCm": 250,
    "sharedMapFraction": 0.5,
    "sharingBand": "high"
  }
}

Limitations and assumptions

Segments must already be appropriate and not unintentionally double counted. No unique family relationship is assigned.

The tool evaluates supplied observations or a declared model. It does not establish the biological cause of an observed pattern. Malformed requests produce input errors. A successfully evaluated request can still contain false flags, empty result lists or a result outside the supplied threshold; those outcomes have the meanings stated above.

Alternative or Complementary methods

Choose Linkage Interval Map for this operation: Build additive genetic-map positions from ordered adjacent interval distances. For a complementary task, use Independent Inbreeding Paths for this operation: Sum caller-validated independent common-ancestor path contributions to offspring inbreeding.

The implementation reference documents the exact calculation, supported input shapes and returned fields.

References

IBD Sharing Bands — tool.io

Similar or alternative tools

Linkage Interval Map
Build additive genetic-map positions from ordered adjacent interval distances.
Independent Inbreeding Paths
Sum caller-validated independent common-ancestor path contributions to offspring inbreeding.