A computational tool for detecting both novel and reference short tandem repeat (STR) expansions, including pathogenic ones, is presented in Genome Biology this week. Expansions of STRs have been identified as the cause of rare Mendelian diseases such as Huntington's disease but detecting them with short-read DNA sequencing data remains a challenge since supporting reads are often mapped incorrectly. To address this, a team led by University of Utah scientists developed STRling. The software, they write, calls alleles both within the read length and greater than the read length, is capable of accurately detecting the genomic position of expansions and can discover and jointly call STRs in thousands of individuals, then prioritize alleles that are large outliers in a given individual. STRling is open source and freely available.