Dementia due to Huntington disease

Description

Dementia due to Huntington disease occurs as part of a widespread degeneration of the brain due to a trinucleotide repeat expansion in the HTT gene, which is transmitted through autosomal dominance. Onset of symptoms is insidious typically in the third and fourth decade of life with gradual and slow progression. Initial symptoms typically include impairments in executive functions with relative sparing of memory, prior to the onset of motor deficits (bradykinesia and chorea) characteristic of Huntington disease.

Coding note

This category should never be used in primary tabulation. The codes are provided for use as supplementary or additional codes when it is desired to identify the presence of dementia in diseases classified elsewhere. When dementia is due to multiple aetiologies, code all that apply.

Coding note from above levels

This category should only be used for primary tabulation, if the aetiology of the dementia is unknown. If the aetiology of the dementia is known code to the aetiology of the dementia for primary tabulation. When dementia is due to multiple aetiologies, code all that apply.

Inclusions

• Dementia in Huntington chorea

Exclusions from above levels

• 6A00 – Disorders of intellectual development
• 6D70 – Delirium
• http://id.who.int/icd/entity/1516623224 – Neurodevelopmental disorders