G71.12 Myotonia congenita

The ICD-10-CM code for Myotonia congenita is G71.12 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

6: Diseases of the nervous system (G00-G99)

Section

G70-G73: Diseases of myoneural junction and muscle (G70-G73)

Category G71

35 codes (28 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to G71.12:

• Thomsen disease
• Myotonia (acquisita) (intermittens) › congenita (acetazolamide responsive) (dominant) (recessive)
• Myotonia (acquisita) (intermittens) › levior
• Disease, diseased › Thomsen
• Disease, diseased › Becker › myotonia congenita
• Becker's › disease › myotonia congenita, recessive form

Inclusion Terms

• Acetazolamide responsive myotonia congenita
• Dominant myotonia congenita [Thomsen disease]
• Myotonia levior
• Recessive myotonia congenita [Becker disease]

U.S. Hospital Utilization

• An estimated 230 U.S. inpatient stays in 2023 included G71.12 among the documented diagnoses.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

Dominant/nondominant side (TOC entry)

a. Dominant/nondominant side ................................................................................................. 45

Pain - Category G89 (TOC entry)

b. Pain - Category G89.............................................................................................................. 45

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)