|Number of repeats||Counts (alleles)||Percentage|
Overview of repeats
Desbuquois dysplasia-2 (DBQD2), also known as the Baratela-Scott syndrome is caused by mutations in the XYLT1 gene and LaCroix et al. (2019) recently discovered that GGC repeat expansions in the XYLT1 can be disease-causing as well. By investigating 12 individuals from 10 families with DBQD2, a 238 bp sequence missing from the reference genome (hg19 and hg38) was discovered. In that sequence, expansions ranging from ~110 to ~850 repeats were found in all patients. The 238 bp sequence was seen to be present in the control group (100 individuals) as well, where GGC repeats were in the range of 9-20 repeats (LaCroix et al., 2019).
NB! The repeated region is not in the hg38 and hg19 reference genome, but the locus can be genotyped by STRipy or with XYLT1 STR caller that is realigning a sample onto a genome containing the 238 bp reference-missing sequence.