Foundations

Explore STR loci across human chromosomes and learn the core concepts behind forensic genetics and bioinformatics workflows.

Explore STR loci in the Genome

Select a chromosome to view its STR loci, then open any marker to see its details.

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Core Concepts

Key principles of forensic STR profiling and interpretation.

From GB to ISFG: allele notation correction for LongTR and HipSTR
LongTR and HipSTR report STR alleles using base-pair differences from the reference, not standard forensic allele numbers. This article explains the math behind the discrepancy, shows why allele 11.8 is actually allele 11.3 in forensic databases, and provides the conversion rule for tetranucleotide, trinucleotide, and pentanucleotide loci.
10 min read

Topics covered:

LongTR
HipSTR
ISFG
From Length to Sequence: CE vs NGS in STR Analysis
CE defines STR alleles by size, while NGS reveals their true sequence. This added resolution improves discrimination and mixture interpretation.
7 min read

Topics covered:

CE
STR
NGS
Forensic STRs
STRs are short DNA sequences repeated in tandem. The allele number reflects how many times the sequence repeats, with decimals indicating partial repeats (e.g., 9.2). Understanding this is key to interpreting forensic STR profiles.
5 min read

Topics covered:

STR
Alleles
Repeats

Bioinformatics

Sequencing formats, alignment, and the data foundations behind STR analysis workflows.

Understanding Sequencing File Formats: An Introductory Guide
Understanding sequencing data storage formats in bioinformatics
7 min read

Topics covered:

FASTA
FASTQ
SAM
BAM
CRAM
FASTQ files
FASTQ files are the foundation of next-generation sequencing analysis. Understanding how to interpret these scores, and when to apply trimming, is essential for ensuring accurate downstream analyses in genomics and bioinformatics.
10 min read

Topics covered:

FASTQ
SAM files
SAM files are the cornerstone of sequence alignment analysis. Useful for inspecting mapping quality, errors, and alignment structure, they are typically converted to BAM for efficient storage and processing. Understanding their fields is essential for accurate variant calling, visualization, and downstream genomic workflows.
10 min read

Topics covered:

SAM