"We describe associated conditions, such as Hymenoptera Reactions, Familial Tryptasemia, Postural Orthostatic Tachycardia Syndrome and Ehlers-Danlos Syndrome."

Mast Cell Activation Syndromes

Rafael Bonamichi-Santos and Mariana Castells

https://link.springer.com/article/10.1007/s40521-016-0100-6

"Results

Comprehensive pedigree analysis of 16 families (39 individuals with orthostatic intolerance, and 40 individuals suspected of having orthostatic intolerance), demonstrated dominant transmission of autonomic dysfunction with incomplete penetrance. Affected individuals were predominantly female (71.8%, 28/39; F:M::2.5:1). Male-to-male transmission, though less common, was observed and demonstrated to transmit through unaffected males with an affected parent. Similar to sporadic orthostatic intolerance, probands report a range of symptoms across multiple organ systems, with headaches and neuromuscular features being most common.
Conclusions

Familial occurrence and vertical transmission of autonomic dysfunction in 16 families suggests a novel genetic syndrome with dominant transmission, incomplete penetrance, and skewing of the sex ratio. Elucidation of potential genetic contributions to orthostatic intolerance may inform therapeutic management and identification of individuals at risk. Adolescent evaluation should include identification and treatment of potential at-risk relatives."

http://www.pedneur.com/article/S0887-8994(16)30419-2/abstract