[Clinical manifestations of myotonic dystrophy: epidemiologic survey].
BACKGROUND
The presence of a local aggregation of cases of myotonic dystrophy (MD) allows the evaluation of clinical symptoms of the disease in a sample in which the influence of a possible genetic heterogeneity is decreased.


METHODS
The degree of global neuromuscular handicap and the incidence and severity of four of the most characteristic symptoms (cataracts, myotonia, muscular weakness and neuropsycologic disturbances) were studied in 183 patients with MD (146 typical adult forms, 19 neonatal, and 18 partial syndromes) in relation with the age of onset of the symptomatology or length of disease.


RESULTS
Only 8.3% of the patients (excluding the neonatal forms) were severely handicapped, and the degree of neuromuscular handicap depended fundamentally on the age of onset of the disease. Cataracts and myotonia were present in 87 and 89% of the patients, respectively. Almost all the patients above the age of 40 presented cataracts. No clinical or subclinical evidence of neuromuscular involvement was present in 11% of the patients with MD. These patients principally corresponded to the group in whom the disease initiated over the age of 50.


CONCLUSIONS
The age of onset of the symptomatology appears to be the determining factor to establish both the global prognosis of neuromuscular incapacity of patients with myotonic dystrophy and the explanation of the chronology of the appearance of the most characteristic symptoms of the disease. The presence of carriers without neuromuscular symptomatology is of note, this fact reinforcing the need to incorporate DNA examination in the evaluation of asymptomatic relatives or with exclusive ocular symptomatology.
López de Munain
A
A
Servicio de Neurología, Hospital Nuestra Señora de Aránzazu, San Sebastían, Guipúzcoa.
Emparanza
J I
JI
Blanco
A
A
Cobo
A
A
Poza
J J
JJ
Basauri
B
B
Baiget
M
M
Martí Massó
J F
JF
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002386:Cataract / Q000209:etiology; D002648:Child; D002675:Child, Preschool; D004247:DNA / Q000032:analysis; D004576:Electromyography; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008875:Middle Aged; D009223:Myotonic Dystrophy / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics / Q000503:physiopathology; D013030:Spain / Q000453:epidemiology
D004247:DNA
Manifestaciones clínicas de la distrofia miotónica: encuesta epidemiológica.