Table 3. [Myopathies of Interest in the Differential Diagnosis of Myotonic Dystrophy Type 2]. - GeneReviews®

Gene	Disorder	MOI	Mean Age at Onset (yrs)	Initial Muscle Group Involved	Serum Creatine Kinase Concentration	Characteristic Features
DES	Desminopathy (OMIM 601419)	AD AR	20-60	Anterior compartment in the legs, later arms	2-10x normal	Weakness of ankle dorsiflexion usually at age 20-60 yrs, then slow progression to proximal leg & arm muscles ± dilated cardiomyopathy & conduction defects
GNE	GNE myopathy	AR	15-20	Anterior compartment in legs	<10x normal	Foot drop & a steppage gait Progression to loss of ambulation after 12-15 yrs
LDB3	Zaspopathy (OMIM 609452)	AD	>40	Anterior compartment in legs	Normal or slightly ↑	Weakness of ankle dorsiflexion usually starting in late 40s, then slow progression to finger & wrist extensor muscles & intrinsic hand muscles Eventually proximal leg muscles become involved. ± dilated cardiomyopathy & conduction defects
MYOT	Myotilinopathy (OMIM 609200)	AD	>40	Posterior > anterior in legs	Slightly ↑	Weakness of ankle extension usually starting in late 40s, then slow progression to proximal leg muscles ± neuropathy & contractures
VCP	Inclusion body myopathy w/Paget disease of bone &/or frontotemporal dementia (valosin containing protein myopathy)	AD	30-60	Proximal muscles lower limb	5-10x normal	Distal paresis & difficulties climbing stairs Progresses to proximal & axial muscles Later: Paget disease of bone & rapidly progressive frontotemporal dementia

Gene

Disorder

MOI

Mean Age at Onset (yrs)

Initial Muscle Group Involved

Serum Creatine Kinase Concentration

Characteristic Features

DES

Desminopathy (OMIM 601419)

AD
AR

20-60

Anterior compartment in the legs, later arms

2-10x normal

Weakness of ankle dorsiflexion usually at age 20-60 yrs, then slow progression to proximal leg & arm muscles
± dilated cardiomyopathy & conduction defects

GNE

GNE myopathy

15-20

Anterior compartment in legs

<10x normal

Foot drop & a steppage gait
Progression to loss of ambulation after 12-15 yrs

LDB3

Zaspopathy (OMIM 609452)

>40

Anterior compartment in legs

Normal or slightly ↑

Weakness of ankle dorsiflexion usually starting in late 40s, then slow progression to finger & wrist extensor muscles & intrinsic hand muscles
Eventually proximal leg muscles become involved.
± dilated cardiomyopathy & conduction defects

MYOT

Myotilinopathy (OMIM 609200)

>40

Posterior > anterior in legs

Slightly ↑

Weakness of ankle extension usually starting in late 40s, then slow progression to proximal leg muscles
± neuropathy & contractures

VCP

Inclusion body myopathy w/Paget disease of bone &/or frontotemporal dementia (valosin containing protein myopathy)

30-60

Proximal muscles lower limb

5-10x normal

Distal paresis & difficulties climbing stairs
Progresses to proximal & axial muscles
Later: Paget disease of bone & rapidly progressive frontotemporal dementia

From: Myotonic Dystrophy Type 2

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Adam MP, Feldman J, Mirzaa GM, et al., editors.

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