ICD-10-CM > G00-G99 > G40-G47 > G47 > G47.4 > G47.42 G47.42 Narcolepsy in conditions classified elsewhere Non-Billable/Non-Specific Code First underlying condition Codes G47.421Narcolepsy in conditions classified elsewhere with cataplexyG47.429Narcolepsy in conditions classified elsewhere without cataplexy