title: Discordant transsexualism in male monozygotic twins: neuroanatomical and psychological differences.
abstract: One monozygotic male twin pair discordant for transsexualism is described. Both twins were interviewed and tested with the Wechsler Adult Intelligence Scale battery for cognitive functions and they underwent magnetic resonance imaging to measure the volumes of specific cerebral structures. Interviews with the twins and their mother indicated no unusual medical or life history events that could have had a causal role in the emergence of the disorder. Both cognitive function testing and neuroimaging detected differences between the twins that could be related to unexplained epigenetic effects and exogenous hormone usage.
authors.affiliation: Gender Identity Disorder Program, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil, tahianasa@yahoo.com.br.
authors.forename: Tahiana Signorini
authors.initials: TS
authors.lastname: Andreazza
authors.forename: Angelo Brandelli
authors.initials: AB
authors.lastname: Costa
authors.forename: Raffael
authors.initials: R
authors.lastname: Massuda
authors.forename: Jaqueline
authors.initials: J
authors.lastname: Salvador
authors.forename: Esalba Maria
authors.initials: EM
authors.lastname: Silveira
authors.forename: Felipe
authors.initials: F
authors.lastname: Piccon
authors.forename: Renata
authors.initials: R
authors.lastname: Carvalho
authors.forename: Anna Martha Vaitses
authors.initials: AM
authors.lastname: Fontanari
authors.forename: Walter
authors.initials: W
authors.lastname: Koff
authors.forename: Paulo
authors.initials: P
authors.lastname: Belmonte-de-Abreu
authors.forename: Maria Inês Rodrigues
authors.initials: MI
authors.lastname: Lobato
mesh_terms: D001921:Brain / Q000473:pathology* / Q000503:physiopathology; D003071:Cognition; D003072:Cognition Disorders / Q000175:diagnosis / Q000235:genetics; D004200:Diseases in Twins; D005260:Female; D005783:Gender Identity; D006801:Humans; D007360:Intelligence / Q000235:genetics; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D057829:Gender-Affirming Procedures; D014189:Transsexualism / Q000523:psychology*; D014430:Twins, Monozygotic / Q000523:psychology*; D055815:Young Adult