Laboratory Abnormalities in Patients With Myotonic Dystrophy Type 2

Abstract

Background: Myotonic dystrophy type 2 (DM2) is a recently discovered adult muscular dystrophy. Similar to DM1, this disease causes progressive debilitating weakness, clinical myotonia, and early cataracts and is thought to cause widespread physiologic dysfunction of multiple organ systems. Objective: To analyze and compile the laboratory abnormalities of patients with DM2. Design: Baseline DM2 laboratory data were compiled representing 68 different types of laboratory tests and 1442 total studies. Setting: University medical center. Patients: Eighty-three adults with genetically confirmed or clinically probable DM2 were identified. Of these patients, 49 had documented baseline laboratory screening. Main Outcome Measures: The individual frequencies of abnormal laboratory values in the population with DM2 studied.Results: Of the 1442 studies, results for 359 (24.9%) were outside of their standard reference ranges. Of the 68 types of laboratory tests studied, 43 had values from 15 or more different patients with DM2. The relative frequency of an abnormally elevated laboratory value was greater than 50% in several tests, including the levels of creatine kinase, total cholesterol, lactate dehydrogenase, and alanine aminotransferase. In addition, serum levels of IgG were low in 75% of all patients with DM2 tested, and absolute lymphocyte counts were low in 54% of all patients with DM2 tested. Conclusions:There is a high frequency of laboratory abnormalities in patients with DM2. These abnormalities provide insight into the widespread pathologic manifestations of DM2 and may form a basis for clinical monitoring and disease screening.

Phenotypic variability and molecular genetics in proximal myotonic myopathy

“…Multiple laboratory abnormalities have been reported in patients with DM2, such as increased levels of CK, cholesterol, LDH, and transaminases, and low absolute lymphocyte count. 20 Mild to moderate CK elevation was seen in 68.8% of our patients, including 1 asymptomatic individual who had laboratory monitoring after starting statins. We also found high levels of ALT, LDH, GGT, and cholesterol in a variable proportion of patients, whereas white blood cell count was decreased in 31.3%.…”

Cardiac Involvement in Myotonic Dystrophy Type 2 Patients With Preserved Ejection Fraction

“…Furthermore, patients are also experienced hypothyroidism, 7 hypercholesterolemia, and hypertriglyceridemia. 8 In a clinical setting, cardiac involvement seems to be rare, but following autopsy data it is underestimated. Already in 1988, before genetic differentiation of subtypes had been introduced, an extended autoptic study reported myocardial fibrosis and local fatty infiltrations in the conduction system of the heart in patients with myotonic dystrophy.…”

Loss of MBNL1 induces RNA misprocessing in the thymus and peripheral blood

“…Although DM1 and DM2 are classified as a muscular dystrophy, the immune system is also affected and both DM types are characterized by a number of cellular and humoral abnormalities in peripheral blood. For example, although hypogammaglobulinemia and low lymphocyte counts occur in both DM types, they are especially prevalent in DM2 and are associated with an increased risk of autoimmune disease in DM2 18,19 . In addition, thymic hyperplasia and thymoma, as well as increased risk for other cancer types, have been reported in DM [20][21][22][23] .…”