This hateful diatribe was surreptiously left by a pathetic creature. She claims to be a mother. From the vile tone of her letter, one might also suspect she's a "pro-life" zealot, one who wants government to police women's uterus as though they were public property, but doesn't want her taxes supporting pre-natal health care, or anything in support of children's well-being once they're born and dependent upon adults' care.
Since the letter's writer suggests that the child she calls a hindrance should be euthanized and "whatever non retarded body parts he possesses" be donated to science, his family have contacted the police to investigate, and hopefully, lay charges.
Autism is a different way of being human. Scientific and educational research is evolving; neurological differences that once were labeled "abnormal" are now accepted as one manifestation of how the brain is organized. Adaptions are still necessary for autistic persons to be be able to navigate a world that is geared to the neurotypical.
The ugliness of that woman's letter harkens to the violence and persecution that albino folks still suffer in regions of the world, for example.
Superstition and ignorance are an affliction; autism is not.
Grand merci to @matttbastard for link to news story.
ADDED by fh: Reaction from someone who knows whereof she speaks.
UPDATE: People rally from all around Oshawa and Newcastle in support of the autistic boy targeted by the letter, and his family.