A patient with 2 different repeat expansion mutations

Background: Many inherited progressive encephalopathies have a poor outcome , and some art caused by repeat expansion mutations. How would the presence of 2 different expansion mutations affect the phenotype? Objective: To describe a patient who has 2 distinct, rare genetic disorders : myotonic dystrophy (DM, OMIM 160900) and progressive myoclonus epilepsy o f the Unverricht-Lundborg type (EPM1, OMIM 254800). Both conditions are cau sed by repeat expansion mutations. They affect the central nervous system c ausing mental retardation, but also product a wide spectrum of disabilities in daily living. Setting: Referral center. Methods: Clinical description with accompanying photographs, electroencepha lography and magnetic resonance imaging; DNA analysis of both of the mutati ons and chromosomal analysis with prometaphase spreads. Results: The patient had clinical characteristics and findings of both myot onic dystrophy and progressive myoclonus epilepsy of the Unverricht-Lundbor g type. Electroencephalographic recordings over a 3-year period showed typi cal findings for myoclonus epilepsy. The patient had no gross anomalies in brain magnetic resonance imaging. She had a normal karyotype, and both of t he diagnoses were confirmed at the molecular level with the direct detectio n of the mutations. Conclusions: Despite hating 2 different progressive inherited disorders aff ecting the central nervous system, the patient, at age 28 years, showed onl y mild mental retardation with very slow progression. However, clear deteri oration in activities of daily living has taken place during last 3 years.