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Myotonia congenita

From SNPedia

Myotonia congenita is a neuromuscular channelopathy that affects skeletal muscles. The disorder is caused by mutations in part of a CLCN1 gene encoding the ClC-1 Chloride channel, resulting in muscle fiber membranes to have an unusually exaggerated response to stimulation (hyperexcitability). Symptoms include delayed relaxation of the muscles after voluntary contraction (myotonia), and may also include stiffness, hypertrophy (enlargement), transient weakness in some mutations, and cramping.Wikipedia

The autosomal recessive form of myotonia congenita, known as Becker myotonia, is more common than the dominant form, which is known as Thomsen's disease. Mutations of the CLCN1 gene leading to either Becker or Thomsens in SNPedia include:


Thomsens, autosomal dominant
rsid i-id (23andMe) synonym (c. or p.) On chip?
rs80356696 i5003260 c.1655A>G, p.Gln552Arg 23andMe v3, 23andMe v4
rs80356700 i5003264 c.689G>A, p.Gly230Glu, G230E 23andMe v3, 23andMe v4
rs80356695 n/a c.1438C>A, p.Pro480Thr
rs80356698 n/a c.2512_2513insCTCA
rs80356686 n/a c.577G>A, p.Glu193Lys
rs80356701 n/a c.920T>C, p.Phe307Ser
rs80356694 n/a c.1439C>T, Pro480Leu
rs80356685 n/a c.592C>G, p.Leu198Val
rs80356690 i5003259 23andMe v3, 23andMe v4
rs80356689 n/a c.857T>C, p.Val286Ala
rs80356699 i5003254 23andMe v3, 23andMe v4
rs121912810 i5003253 p.Ser189Phe 23andMe v3, 23andMe v4
rs80356691 n/a c.929C>T, Thr310Met


Both dominant and recessive
rsid i-id (23andMe) synonym (c. or p.) On chip?
rs80356702 i5003257 c.950G>A, p.Arg317Gln 23andMe v3, 23andMe v4
rs80356693 n/a c.1412C>T, p.Ser471Phe
rs80356692 n/a c.937G>A, Ala313Thr
rs80356703 n/a c.1013G>A, p.Arg338Gln
rs80356697 n/a c.1667T>A, p.Ile556Asn
rs80356684 n/a c.394A>T, p.Ser132Cys
rs80356688 n/a c.847C>T, p.Leu283Phe
rs55960271 i6056364 c.2680C>T, p.Arg894Ter 23andMe v3, 23andMe v4, Ancestry v2


Becker, autosomal recessive
rsid i-id (23andMe) synonym (c. or p.) On chip?
rs80356704 n/a c.1592C>T, p.Ala531Val
rs121912799 n/a p.Phe413Cys
rs121912801 n/a
rs121912805 i5003258 c.871G>A, p.Glu291Lys 23andMe v3, 23andMe v4
rs80356687 n/a c.803C>T, p.Thr268Met
rs121912807 n/a c.1495G>A, p.Gly499Arg
rs80356706 i5003255 23andMe v3, 23andMe v4