The nosological place of scapuloperoneal muscular dystrophy with minimal affection of the facial muscles (FSPD) is not fully defined: Is it an independent form or a variant of FSHD?
We observed the pattern of muscle affections in two 4q35 linked facioscapuloperoneal muscular dystrophy (FSPMD) families in which the patients were re-examined by V.K. after 27 - 28 and 35 - 37 years. In first family (the 4q35 p13E-11 EcoRI/BlnI DNA fragment size 24/27 kb) the proband at the age of 36 had a pure severe scapuloperoneal phenotype with minimal affection of orbicularis oris muscles on the left side which transferred into final facio-scapulo-peroneal-femoro (posterior thigh muscles)-gluteo (gluteus maximus)- (humeral, biceps brachii on grade 4 on the left side) [FSPFG(H)] phenotype at the age of 73, on re-examination of the patient after 37 years. In proband’s brother at the age of 36 and at the re-examination after 37 years at the age of 73 there was the same pure severe scapuloperoneal phenotype with mild atrophy of upper lip on the right side. However, on MRI of lower limb muscles the severe involvement of some posterior thigh muscles and rectus femoris was found. The proband’s niece at the age of 6 was presymptomatic with facio(scapular) phenotype which transferred into pure moderate facioscapuloperoneal (FSP) phenotype with severe affection orbicularis oris muscle at the age of 42, on re-examination after 36 years. However, on MRI of lower limb muscles the severe involvement of posterior thigh muscles and rectus femoris was found.
In the second family (DNA fragment size 23/20 kb) the proband at the age of 60 had a pure severe scapuloperoneal phenotype with minimal weakness of orbicularis oculi muscles which transferred in final FSPFG(H) phenotype with slight affection of biceps brachii muscle on the left side at the age of 88, on re-examination after 28 years. The proband’s daughter at the age of 28 and on re-examination after 27 years, at the age of 55, had the same mild (F)SP phenotype. The proband’s granddaughter at the age of 5.5 was presymptomatic with facio(scapular) phenotype. On re-examination after 24 years she had a pure severe FSP with severe affection facial muscles which transferred in FSP(F) phenotype with mild affection of posterior thigh muscles at the age of 41, on re-examination after 35 years. However, on MRI of lower limb muscles the total involvement of posterior thigh muscles was found. Thus, in observed members the disease began with initial involvement of the face and shoulder girdle muscles and some time later of the peroneal group (anterior tibial) muscles. However, in two probands the dystrophic process gradually was extended to the thighs (posterior group, namely), pelvic girdle (gluteus maximus, namely) and upper arm (biceps brachii; slightly weakened on the one side) and in three their relatives with clinical FSP phenotype the severe involvement of some posterior thigh muscles on MRI study was revealed. Our present clinical and MRI data, as well as our more early investigations (1–3), allow supposing that FSP muscular dystrophy is probably an independent form with “hard” static and dynamic pattern of muscle involvement. The term “facioscapulolimb muscular dystrophy, type 2 (FSLD2), descending with a “jump” with initial FSP phenotype” would be more correct. The FSP phenotype constitutes merely a stage in the development of FSLD2. We suppose that classical AD FSPMD (or FSLD2, a descending with a “jump” with initial FSP phenotype) is different from the classical FSHD (or FSLD1, a gradually descending with initial FSH phenotype) although these both diseases are connected with the same 4q35 chromosomal deletion.