Schematic diagrams and electropherograms at breakpoints of large genomic deletions in COL6A1 and COL6A2. We found a deletion of 216 bp (COL6A1) in transcripts in Family #3 and #4, and a deletion of 144 bp (COL6A1) and 99 bp (COL6A2) in transcripts in Family #5 and #87, respectively. At the genomic level, Family #3 and #4 carried a deletion of 1.2 kb spanning from IVS4-7 to IVS8+490 in COL6A1 (a). The 5′ breakpoint of the 2.1 kb deletion found in Family #5 was located at the sixth base of exon 8 of COL6A1 and its 3′ breakpoint was at − 43 of intron 10 (b). One of the COL6A2 alleles of Family #87 contained a 1.2 kb deletion extending from IVS7+102 to IVS10-43 (c). E: exon sequence. The numbering of genomic positions at the breakpoints are based on the sequence from the Gene Reference Consortium GRCh37/hg19.