Research confirms that environmental factors are linked to the development of PANDAS. Genetically identical siblings were enrolled in the study. This is the abstract of recent research (technical):
Termed pediatric autoimmune neuropsychiatric disorders associated with Streptococcus (PANDAS), these cases of childhood-onset obsessive compulsive disorder and tic disorders resemble the presentation of Sydenham chorea, in that they have an acute onset following a group A beta-hemolytic streptococcal infection (group A Streptococcus), with accompanying neurological signs, and an episodic or sawtooth course. Familial associations of this subgroup of patients remain understudied.
This report provides phenotypic descriptions of three youth with PANDAS as well as their genetically identical siblings (in two cases of twins and one case of triplets). These cases highlight the potential for environmental influences for discordant presentations in genetically identical siblings. Despite identical genetics, presentations showed marked variation across siblings (from a full PANDAS presentation to asymptomatic).
Further research into environmentally driven influences such as postinfectious molecular mimicry and epigenetic factors that may influence the manifestation of these pediatric neuropsychiatric disorders will promote our understanding of their prevention and treatment.
Rothman Center for Neuropsychiatry, Department of Pediatrics, University of South Florida College of Medicine , St. Petersburg, Florida. Lewin AB, Storch EA, Murphy TK. J Child Adolesc Psychopharmacol. 2011 Apr, 21(2):177-82. Epub 2011 Apr 12.