G71.12
Myotonia congenita
G71.12 (also written G7112) is a billable ICD-10-CM diagnosis code for myotonia congenita. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 28 codes in category G71 (Primary disorders of muscles). The Alphabetic Index lists it under 6 entries. Its coding notes include 11 Excludes2 entries.
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
Also from chapter/block level (8 notes)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Care settings
How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.
Home Health Primary
Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the Neuro Rehabilitation clinical group.
Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026IRF 60% Rule
On the CMS list of diagnoses used to determine presumptive compliance with the IRF 60 percent rule.
Source: CMS IRF Presumptive Compliance-3, FY 2027 IRF PPS final rule files, effective for discharges on or after October 1, 2026Inclusion terms
Conditions classified to this code.
- Acetazolamide responsive myotonia congenita
- Dominant myotonia congenita [Thomsen disease]
- Myotonia levior
- Recessive myotonia congenita [Becker disease]
Alphabetic Index terms
Terms the official Alphabetic Index lists for this code. 6 entries