Gennarelli et al listed the clinical features associated with the 3 main recognized phenotypes of myotonic dystrophy. It is a multisystem disorder primarily associated with skeletal muscle dysfunction.
Phenotypes recognized:
(1) late onset (middle or old age)
(2) juvenile to adult
(3) congenital
Parameters:
(1) muscle impairment
(2) facial features
(3) cardiac features
(4) endocrine features
(5) mental retardation
(6) other
|
Parameter |
Phenotype 1 (middle/old age) |
Phenotype 2 (juvenile/adult) |
Phenotype 3 (congenital) |
|
muscle |
minimal myotonia no impairment facial weakness facial muscle wasting |
myotonia distal weakness |
proximal weakness |
|
facial |
frontal balding ptosis nasal speech |
|
|
|
cardiac |
none |
ECG changes |
cardiomyopathy |
|
endocrine |
minor |
glucose intolerance hypogonadism |
clinical dysfunction |
|
mental retardation |
none |
mild |
moderate to severe |
|
other |
cataract |
cataract |
cataract talipes |
Facial muscle wasting in phenotype 1:
(1) jaw
(2) temporalis
(3) sternocleidomastoid muscles
Patients with phenotype 2 may show isolated proximal muscle weakness in the triceps brachii.
Specialty: Genetics
ICD-10: ,
