Short GCG expansions in the PABP2 gene cause oculopharyngeal muscular dystrophy.

Autosomal dominant oculopharyngeal muscular dystrophy (OPMD) is an adult-onset disease with a world-wide distribution. It usually presents in the sixth decade with progressive swallowing difficulties (dysphagia), eyelid drooping (ptosis) and proximal limb weakness. Unique nuclear filament inclusions in skeletal muscle fibres are its pathological hallmark. We isolated the poly(A) binding protein 2 gene (PABP2) from a 217-kb candidate interval on chromosome 14q11 (B.B. et al., manuscript submitted). A (GCG)6 repeat encoding a polyalanine tract located at the N terminus of the protein was expanded to (GCG)8-13 in the 144 OPMD families screened. More severe phenotypes were observed in compound heterozygotes for the (GCG)9 mutation and a (GCG)7 allele that is found in 2% of the population, whereas homozygosity for the (GCG)7 allele leads to autosomal recessive OPMD. Thus the (GCG)7 allele is an example of a polymorphism which can act either as a modifier of a dominant phenotype or as a recessive mutation. Pathological expansions of the polyalanine tract may cause mutated PABP2 oligomers to accumulate as filament inclusions in nuclei.

Oculopharyngeal muscular dystrophy in two unrelated Japanese families.

The occurrence of oculopharyngeal muscular dystrophy (OPMD) in Orientals is uncertain. We identified two unrelated Japanese families, including 30 affected individuals (14 men, 16 women, mean age 58 years) of OPMD through four generations, with complete penetrance. Their major clinical manifestations were late-onset bilateral ptosis and dysphagia. Histologic studies of slightly affected muscles reveal mild myogenic changes, occasional rimmed vacuoles, and small angulated fibers. By contrast, the severely involved cricopharyngeal muscle showed marked loss of fibers and massive proliferation of connective tissue. Ultrastructural studies of four different biopsied muscles disclosed subsarcolemmal intranuclear tubulofilamentous inclusions, identical to those of non-Japanese OPMD patients.

Oculopharyngeal muscular dystrophy in Japan.

Oculopharyngeal muscular dystrophy (OPMD) in the European population has been frequently diagnosed, but except for one black family, the occurrence in other ethnic groups is uncertain. We identified two unrelated OPMD Japanese families, including 34 affected individuals. Major clinical manifestations were bilateral ptosis and dysphagia starting after age 40. Histologic studies of limb muscles revealed mild myogenic changes, occasional rimmed vacuoles, and small angulated fibers. By contrast, cricopharyngeal muscle showed a marked loss of fibers and massive proliferation of connective tissue. Intranuclear tubulofilamentous inclusions (ITFI) of 8.5 nm outer diameter were observed in 2-5% of the nuclei in four different biopsied muscles. One patient with recurrent aspirations underwent successful cricopharyngeal myotomy. Aerodynamic examination was useful to evaluate velopharyngeal closure function. Our investigations revealed that OPMD is a geographically widespread disorder, and ITFI may be the specific morphologic hallmark.

[A Japanese pedigree with oculopharyngeal muscular dystrophy].

We investigated a Japanese pedigree with oculopharyngeal muscular dystrophy (OPMD) which included the probands of two sisters and a brother. Case 1 (Fig. 1): A woman born in 1940 at Fuji City, Shizuoka prefecture (Pacific coast side, which located about 80 miles west from Tokyo) was insidiously suffering from dysphagia and eye lid ptosis since her age of 40. She was admitted to Shizuoka Red Cross Hospital when 48 years old, because of difficulty of going upstairs. Neurological examination revealed severe eye lid ptosis without eye movement disorders, dysphagia, and moderate weakness on neck and proximal muscles of extremities without definite atrophy and fasciculation. In the laboratory data, serum creatine kinase level was slightly elevated to 215 U/l. Electromyographic findings showed myogenic pattern on the extremities but no evidence of the existence of myasthenia gravis and neurogenic involvement. Intranuclear tubular filaments were found in 3% of muscle fibers from her left biceps muscle. Case 2: The elder sister of the case 1 was suffering from eye lid ptosis without eye movement disorder and severe dysphagia since the age of 44. Case 3: The younger brother of the case 1 was suffering from dysphagia and proximal muscle weakness since the age of 40. We found eye lid ptosis, dysphagia and/or proximal muscle weakness in 24 cases (men: 12 cases, women: 12 cases) out of 50 examined members of this pedigree after their ages of 40 (Fig.3; family tree). It was concluded that this pedigree had cases of oculopharyngeal muscular dystrophy with autosomal dominant inheritance which was quite rare in Japanese.

[A case of metamorphopsia caused by a very localized spotty infarct].

A 51-year-old woman complained that her right side of the face looked blurring and the right margin of all the objects in her visual field looked blurred. Neurological examination on admission showed no abnormalities including higher cortical function and visual fields except the metamorphopsia. In this case, a very localized spotty infarct caused no neurological symptoms other than the metamorphopsia. CT scan and MRI revealed a spotty lesion of infarct between retrosplenium and cingulate gyrus on the left side. This can be a breakthrough case to locate the exact anatomic pathology that causes metamorphopsia.