Preimplantation Genetic Diagnosis - For 'Disabilities?'

The New York Times just ran an article (Wanting Babies Like Themselves, Some Parents Choose Genetic Defects) that completely blows me away. The topic is preimplantation genetic diagnosis, but rather than the usual 'building the perfect baby' angle the article discusses parents with 'disabilities' who want to leverage the technology to introduce the same conditions into their unborn childern.

Huh?

From the article:
Wanting to have children who follow in one’s footsteps is an understandable desire. But a coming article in the journal Fertility and Sterility offers a fascinating glimpse into how far some parents may go to ensure that their children stay in their world — by intentionally choosing malfunctioning genes that produce disabilities like deafness or dwarfism.

I guess I'd never thought about it applying in that direction. I'd always assumed that a parent with dwafism or deafness wouldn't want their child to experience and grow up with the same condition. I'm curious whether the desire for the child to share the condition is due to an honest belief that their lives were enriched by the condition, or a concern that they wouldn't be able to raise or deal with a child who lacked their 'disability.'

Interesting stuff...

Genetic Inheritance By Paramutation

This came as a bit of a surprise to me. I was taught early on that we each inherited two sets of genes, one from our mother and one from our father in the form of DNA. These inherited genes were then responsible for all of our genetically governed traits. This article in the Economist (subscription required) suggests that

genetic information comes from places other than inherited DNA.

Based on studies of a gene called Kit French researches believe they have found that in some cases RNA can be passed from parent to child... but in this case RNA that has no relation to the DNA passed from that parent. In this manner, offspring may end up with RNA, and thereby DNA from a parent or grandparent, but lack the DNA that would have been expected to code for that RNA. The article states:

When this RNA was extracted and injected into mice embryos, a white-tailed mutant was created—even though no genes for the white tail were present. This work shows that the inheritance is mediated by RNA but the precise mechanism is unclear. The inherited RNA could be interfering with messages sent by the inherited DNA, or it could be directly modifying inherited DNA.

The phenomenon observed has been coined paramutation and is believe to be able to persist across generations, and has been grouped as an 'epigenetic' effect - defined in the article as

hereditary changes in gene function put down to chemical changes rather than the sequence of DNA.

From The Economist