Phenotypes Associated with This Genotype

Genotype
MGI:3613741

• Allelic Composition: Dmpk^tm1Rdd/Dmpk⁺
• Genetic Background: involves: 129S2/SvPas * C57BL/6J

• ♀: phenotype observed in females
• ♂: phenotype observed in males
• N: normal phenotype

muscle

abnormal sarcomere morphology ( J:53077 )

• ultrastructurally, occasional skeletal muscle fibers display sarcomeric disorganization

decreased skeletal muscle fiber diameter ( J:33714 )

• adult (7-11-month-old) heterozygotes display small diameter muscle fibers relative to wild-type mice

impaired skeletal muscle contractility ( J:33714 )

• adult (7-11-month-old) heterozygotes exhibit a variable reduction in tetanic force generation relative to wild-type mice

enhanced skeletal muscle regeneration ( J:33714 )

• adult (7-11-month-old) heterozygotes show increased skeletal muscle regenerative activity, as indicated by small increases in MyoD levels

myopathy ( J:33714 )

• adult (7-11-month-old) heterozygotes display only a subtle, variable myopathy relative to age-matched homozygotes

• notably, heterozygous pups exhibit no overt symptoms of congenital myotonic dystrophy, including muscle hypotonia

• in addition, heterozygotes do not exhibit myotonia, which is a hallmark of the human disease

cardiovascular system

heart block ( J:53077 )

• adult heterozygotes exhibit a cardiac conduction defect (first-degree heart block), in the presence of normal intrinsic sinus node function

atrioventricular block ( J:53077 )

• similar to homozygotes, all adult heterozygotes display first-degree A-V block

• however, unlike homozygotes, adult heterozygotes display no higher-grade atrioventricular block

prolonged PR interval ( J:53077 )

• prolonged mean P-R interval of 48 8 ms vs 34 5 in wild-type mice, but a normal P-wave duration and QRS interval

Mouse Models of Human Disease		DO ID	OMIM ID(s)	Ref(s)
myotonic dystrophy type 1		DOID:11722	OMIM:160900	J:53077