VP.25 Muscle MRI in female carriers of Duchenne muscular dystrophy

Abstract

Muscle magnetic resonance imaging (mMRI) has been proved to be a reliable biomarker of disease severity and progression in patients with Duchenne and Becker muscular dystrophy (DMD/BMD). Although up to 20% of female carriers of DMD/BMD experienced symptoms, there is a paucity of data on mMRI in this patient group. Here, we report a case of a female DMD carrier who had mild clinical symptoms, yet mMRI revealed striking fatty infiltration. A 58-year-old female DMD carrier initially presented in 2020 with a 3-year history of slowly progressive symmetric pelvic girdle weakness since age 53. She was known to be a female DMD carrier at age 26 by linkage analysis, when her brother lost ambulation at age 10 and deceased at age 21 due to cardiopulmonary dysfunction. Subsequently, genetic testing of this patient and her mother both demonstrated deletion of exons 51-55 of the dystrophin gene. X inactivation study was not informative as the patient is homozygous for the polymorphic androgen receptor gene locus analyzed. On exam, the patient has normal muscle strength and a normal walking gait, but slight stepping to ascend steps, jump and hop. Brooke scale and functional Mobility Score were 1. Timed function test remained relatively stable over a time span of 22 months. mMRI of her pelvic and thigh muscles was performed to evaluate the progression of a dystrophic process. There was no significant edema in the musculature of the pelvis and thighs. However, there was striking fatty infiltration in multiple muscle groups, including glutei, adductors, hamstrings, as well as vastus lateralis and intermedius. This case of symptomatic female carrier suggests a possible clinical-radiological mismatch phenomenon in manifesting female carriers of DMD. Further study is indicated to understand the clinical implications of this observation.