Background: Facioscapulohumeral muscular dystrophy is the third most
commonly found type of muscular dystrophy. The aim of this study was to
correlate the D4Z4 repeat array fragment size to the orofacial muscle
weakening exhibited in a group of patients with a genetically supported
diagnosis of FSHD. Methods: Molecular genetic analysis was performed for
52 patients (27 female and 25 male) from a group that consisted of 36
patients with autosomal dominant pedigrees and 16 patients with either
sporadic or unknown family status. The patients were tested with the
southern blotting technique, using EcoRI/Avrll double digestion, and
fragments were detected by a p13E-11 telomeric probe. Spearman's
correlation was used to compare the fragment size with the degree of
muscle weakening found in the forehead, periocular and perioral muscles.
Results: A positive non-significant correlation between the DNA fragment
size and severity of muscle weakness was found for the forehead (r =
0.27; p = 0187), the periocular (r = 0.24; p = 0.232) and the left and
right perioral (r = 0.29; p = 0.122), (r = 0.32; p = 0.085) muscles.
Conclusions: Although FSHD patients exhibited a decrease in muscular
activity related to the forehead, perioral, and periocular muscles the
genotype-phenotype associations confirmed a weak to moderate
non-significant correlation between repeat size and the severity of
muscle weakness. Orofacial muscle weakening and its association with a
D4Z4 contraction alone may not have the significance to serve as a
prognostic biomarker, due to the weak to moderate association. Further
studies with larger sample sizes are needed to determine the degree of
genetic involvement in the facial growth in FSHD patients
