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Myotonia Congenita/Becker's
My daughter was just diagnosed with having mutations on the CLCN1 Gene.  Does this mean that she has the recessive form of Myotonia Congenita or Becker's Disease?  Or does it mean that she received 2 recessive genes from her dad and I which makes her situations even more severe?  I also would like to know of Becker's Disease is the same thing as Beckers MD?  I haven't found any information on females having this form of Muscular Dystrophy.  Is there a source for more info?
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Becker Myotonia Congenita is not the same as Becker's MD

All forms of myotonia congenita are due to mutations on the CLCN1 gene.

Before genetic testing, Becker Myotonia Congenita was distinguished from Thomsen Myotonia Congenita by inheritance and symptom manifestation. Thomsen Myotonia Congenita was found in multiple generations of one family, typically affected the hands and face more severely than the legs, and had an onset very early in life.

Becker Myotonia Congenita, on the other hand, was the name given for myotonia congenita that only affected on generation of a family...often times only one member, primarly affected the legs, or upper and lower body equally, and was more severe in general than Thomsen MC.

With the advent of genetic testing, they found that, as suspected, Thomsen MC was dominant, and suffers only had to have one mutated CLCN1 allele to have the disorder,while Becker MC was recessive and required a mutation on both CLCN1 alleles.

But then it got a little trickier.

The more genetic testing was done, researchers started to discover that some mutations that were thought to be recessive could cause myotonia congenita by itself, when the other CLCN1 allele was free of mutations, and in some families, multiple generations were affected by this.

Generally speaking though, if you have two primarily recessive mutations, you have Becker Myotonia Congenita, and if you have one mutation alone and have symptoms, you have Thomsen Myotonia Congenita.

One thing that has been observed and that is becoming more prevalent in medical literature on the disorder is that people with Becker MC are more likely to have weakness associated with the disorder, in one form or another, and this is generally not seen in those with Thomsen MC.
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