AT Skew

Calculate AT skew as (A−T)/(A+T) from a canonical DNA sequence.

Description

AT skew compares adenine with thymine abundance in canonical DNA.

AT skew compares adenine with thymine abundance in canonical DNA. It describes composition relative to the A/T subset.

Calculate AT skew as (A−T)/(A+T) from a canonical DNA sequence.

When to use AT Skew

Use this for the following task: Calculate AT skew as (A−T)/(A+T) from a canonical DNA sequence.

Prepare the caller-filtered sequences, counts, coordinates or annotations requested below. Keep identifiers and paired lists aligned on the same reference.

How to use AT Skew and understand its results

Prepare the caller-filtered sequences, counts, coordinates or annotations requested below. Keep identifiers and paired lists aligned on the same reference.
Enter sequence using the field table, then run the tool.
Read aCount, tCount, atSkew. 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
sequence	Sequence	string; minimum text length 1; maximum text length 1000000; pattern ^\s[ACGTacgt]+\s$	Required

Normalize the sequence, count A and T and require their sum positive before division.^[1]

AT skew = (A−T)/(A+T)

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

Output field	Meaning	Value type
aCount	A count	integer
tCount	T count	integer
atSkew	AT skew	number

json

{
  "input": {
    "sequence": "AAAT"
  },
  "output": {
    "aCount": 3,
    "tCount": 1,
    "atSkew": 0.5
  }
}

Limitations and assumptions

The tool does not infer biological strand or replication direction. A sequence with only G/C produces an input error.

The tool operates on supplied local data; alignment, filtering and annotation must already be appropriate for the stated calculation. 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 GC Skew for this operation: Calculate GC skew and compositional bias without inferring replication strand from skew alone. For a complementary task, use Sliding GC Content for this operation: Calculate GC content in complete DNA windows at a chosen step size.

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

References

AT Skew — tool.io

Similar or alternative tools

GC Skew
Calculate GC skew and compositional bias without inferring replication strand from skew alone.
Sliding GC Content
Calculate GC content in complete DNA windows at a chosen step size.