Family history of associated disorders in patients with postural tachycardia syndrome

Introduction: Postural tachycardia syndrome is more frequently being recognised in adolescents and adults. However, its pathophysiology remains undefined. We evaluated our database for patterns in family history of clinical symptoms and associated disorders in these patients. Materials and methods: Patients with postural tachycardia syndrome diagnosed in our clinic between 2014 and 2018 and who were less than 19 years at diagnosis were included. The history was reviewed for family members with postural tachycardia syndrome, dizziness and/or syncope, joint hypermobility with or without hypermobile Ehlers-Danlos syndrome, and autoimmune disorders. Statistical analysis assessed the entire cohort plus differences in gender, presence or absence of joint hypermobility, and presence or absence of familial autoimmune disease. Results: A total of 579 patients met inclusion criteria. We found that 14.2% of patients had a family member with postural tachycardia syndrome, with male patients more likely to have an affected family member (20% versus 12.7%, p = 0.04). If the patient also had joint hypermobility, male patients were more likely to have a family member with postural tachycardia syndrome (25% versus 12.6%, p = 0.017), more than one affected family member (7.1% versus 0.74%, p = 0.001), and a family member with joint hypermobility (37.5% versus 23.7%, p = 0.032). Autoimmune disease was seen in 45.1% of family members, but more likely in female patients with concurrent hypermobility (21.1% versus 8.9%, p = 0.035). Discussion: This in-depth analysis of associated familial disorders in patients with postural tachycardia syndrome offers further insight into the pathophysiology of the disorder, and informs further screening of family members in these patients.