The Clinical Profiles And Molecular Biological Charcteristics Of Kennedy's Disease And Myotonic Dystrophy 1

ObjectiveTo investigate the diagnosis of KD and DM1 according to their clinical profiles and molecular biological characteristics, and discuss the possible pathogenesis of this two diseases.MethodOne patient with suspected Kennedy's disease (KD) and one patient with suspected myotonic dystrophy type 1(DM 1) was investigated in our in-patient center. Muscle biopsy and histopathological staining was performed. Samples were observed under the light microscope and electric microscope repectively. The DNA was extracted from the blood samples for the subsequent PCR and sequencing.ResultsThe pathological characteristics of the KD patient match the common features of spinal muscular dystrophy. Prominent neurogenic amyotrophy, clumping of abundant atrophic small diameter fibers, disorganized myofibrillar network and predominant type-2 fiber could be observed under the microscope. Forty-seven repeats of polymorphic CAG tandem-repeat expansion has been detected in this patient, which meets the criteria for the diagnosis of KD. The extremely hypertrophic type 2 fibers, dramatic increased central nuclei and predominance of atrophic type 1 fibres could be discovered in the muscle sample of the DM1 patient. Eighty-three repeats of CTG expansion have been detected in this patient in gene sequencing.ConclusionMuscle biopsy is an important tool for the diagnosis of KD and DM1, and could disclosure the pathological characteristics of KD and DM1. This procedure is simple, convenient and feasible. As the golden standard, genetic analysis plays a critical role in the diagnosis and differential diagnosis of this two diseases.