More than one-fifth of patients who are carriers of the m.3243A>G mutation, one of the most common genetic variants linked to MELAS spectrum disorder, have a significantly higher fear of disease progression, a study shows. Recognizing this fear as a limiting psychological symptom with real implications in a person’s daily life can have major impact on the care and outcome of patients with mitochondrial diseases. The study, “Fear of disease progression in carriers of the m.3243A > G mutation,” was published in the Orphanet Journal of Rare Diseases. Several genetic defects have been identified as the cause of mitochondrial disorders. The onset, manifestation, and overall course of these different syndromes are very variable, even among patients with similar conditions. “The serious nature and erratic, complex presentation of mitochondrial disease often make it difficult to establish a diagnosis and may contribute to increased stress,” the researchers wrote in this study. Due to the serious consequences a diagnosis of mitochondrial disease may represent, it is not uncommon for patients to experience some levels of fear concerning the course of their condition. Fear of disease progression is one of the most important stressors for patients with a life-threatening disease. It has been previously described in patients with other diseases, including cancer, multiple sclerosis, diabetes, and Parkinson’s. However, until now, this has not been fully assessed in patients with heterogeneous (variable presentation), inheritable mitochondrial disease. The study included 76 patients who were known carriers of the m.3243A>G mutation and were seen at the Radboud Center for Mitochondrial Medicine in the Netherlands. Evaluation of the group showed that three patients were asymptomatic, 17% had mild symptoms, 45% had moderate symptoms, and 33% had severe symptoms of the disease. In general, the mean score of disease status, as determined by the Newcastle Mitochondrial Disease Scale for Adults (NMDAS), where higher scores indicate more severe disease, ranged between zero and 86. Approximately 25% were found to have clinically relevant symptoms of anxiety and 26.3% had symptoms of depression. In general, 46% had experienced significant levels of general distress. Analysis of the participants’ fear of progression showed that 14 patients (18.4%) had high levels of fear. The highest fear scores were associated with the possibility that their children could inherit the disease, progression of the disease, and worrying about their family if something happened to them. In contrast, the lowest scores were related to medical appointments and treatments. No associations were found between fear of progression and the patients’ age, marital status, having children, level of education, or employment status. However, women tended to experience more fear than men. Additional analysis did not find any association between fear of progression and NMDAS scores. When the team reanalyzed the data based on NMDAS categories — mild, moderate, and severe disease — significant differences emerged. Patients with moderate to severe disease had much more fear of progression than patients with mild symptoms. Researchers also found significant correlations between fear of disease progression and patients’ physical and social functioning, general health status, pain, and fatigue levels. The levels of anxiety, general distress, and depression were also related to fear of progression. “These results confirm that dealing with this mitochondrial disease is characterized by dealing with uncertainty about future, disease course, and hereditary concerns,” the researchers wrote. “Given that both general distress and fear of disease progression are associated with a lower quality of life and restrictions or problems in daily life, it is important in this patient group to assess mental functioning in clinical consultations and assist patients in accessing appropriate and available support,” they suggested.