Recent Genetics Study

[Stochastic]

I did not have access to the full article, so the abstract is all I have .


Association Study of ERβ, AR, and CYP19A1 Genes and MtF Transsexualism
The Journal of Sexual Medicine, 2014
Fernández, R. and others
http://onlinelibrary.wiley.com/doi/10.1111/jsm.12673/abstract;jsessionid=9C005D8FA00062AE518A79516C0255A9.f03t01?deniedAccessCustomisedMessage=&userIsAuthenticated=false

Abstract

Introduction The etiology of male-to-female (MtF) transsexualism is unknown. Both genetic and neurological factors may play an important role.

Aim To investigate the possible influence of the genetic factor on the etiology of MtF transsexualism.

Methods We carried out a cytogenetic and molecular analysis in 442 MtFs and 473 healthy, age- and geographical origin-matched XY control males. The karyotype was investigated by G-banding and by high-density array in the transsexual group. The molecular analysis involved three tandem variable regions of genes estrogen receptor β (ERβ) (CA tandem repeats in intron 5), androgen receptor (AR) (CAG tandem repeats in exon 1), and CYP19A1 (TTTA tandem repeats in intron 4). The allele and genotype frequencies, after division into short and long alleles, were obtained.

Main Outcome Measures We investigated the association between genotype and transsexualism by performing a molecular analysis of three variable regions of genes ERβ, AR, and CYP19A1 in 915 individuals (442 MtFs and 473 control males).

Results Most MtFs showed an unremarkable 46,XY karyotype (97.96%). No specific chromosome aberration was associated with MtF transsexualism, and prevalence of aneuploidy (2.04%) was slightly higher than in the general population. Molecular analyses showed no significant difference in allelic or genotypic distribution of the genes examined between MtFs and controls. Moreover, molecular findings presented no evidence of an association between the sex hormone-related genes (ERβ, AR, and CYP19A1) and MtF transsexualism.

Conclusions The study suggests that the analysis of karyotype provides limited information in these subjects. Variable regions analyzed from ERβ, AR, and CYP19A1 are not associated with MtF transsexualism. Nevertheless, this does not exclude other polymorphic regions not analyzed.

[suzifrommd]

I've come across several pair of identical twins, one of whom was trans and the other wasn't. That tends to indicate non-genetic factors.

[Danielle79]

I think that mosaicism is one possible genetic explanation that would explain why identical twins need not both be trans.

[Amy The Bookworm]

I've come across several pair of identical twins, one of whom was trans and the other wasn't. That tends to indicate non-genetic factors.

Identical twins aren't 100% identical genetically, because genetic development and modification are also influenced by environment (environment is from the womb during development all the way through out the world through life).  This is why some identical twins are different heights or come down with different diseases.

There are plenty of examples of genetic twins being transgender, and one theory for part of what may cause people to be transgender is hormone exposure during pregnancy. Maybe it's possible that one twin simply gets exposed to not enough of the corresponding hormone? I remember reading somewhere that being a twin (specifically the younger twin) can up the odds of being transgender ... wish I could remember or find the source for that. Anyway, it's entirely possible for identical twins to not match gender wise if there's a genetic link.

Genetics are so complex. Even if they do find a transgender or gay genetic link, that wording is severely simplifying things when reporters and scientists say that. Genetic traits are a whole series of codes within genetics with multiple on off switches and links and conditions of exposure or lack of exposure and on and on to cause one trait.

That modern scientists can find any is amazing by itself, and makes things like cloning and growing body parts as actual viable reality so much more amazing than they already are. We live in amazing times, and the future is going to be beyond our imagination and comprehension ... if we don't somehow wipe ourselves out or collapse the world's economy into total ruin, that is.