Fig. 2.

Molecular diagnosis by DNA Combing. Combed DNA from the different family members using specific probes and bar code for the 4q and 10q regions. The chromosome, haplotype and D4Z4 array size estimation (in kb) is indicated for each allele. The bar-code used to distinguish the three different alleles is based on a combination of three different colors and different DNA probes encompassing the distal regions up to the telomeric sequence [19]. The 3-color barcode comprises 2 probes detected in blue for the proximal region common to chromosomes 4 and 10, one 6 kb probe (red), which hybridizes the telomere, and a red probe that hybridizes the qA-specific β-satellite region, with a variable length (1–5 kb). The qB-specific probe, immediately adjacent to D4Z4, is detected in blue (Additional file 1: Figure S1)