Articles

Posts Tagged Genetics

The FDA and Personalized Genetic Testing

The company 23andMe provides personal genetic testing from a convenient home saliva sample kit. Their home page indicates that their $99 genetic screening will provide reports on 240+ health conditions in addition to giving you information on your genetic lineage. The benefits, they claim, are that you will learn about your carrier status and therefore the risk of passing on genetic diseases to your children. The information will also inform you about health risks so that you can change your behavior to manage them. Finally the genetic information will tell you about how you might respond to different drugs so that you can “arm your doctor with information.”

The home page also contains a link to testimonials about how their DNA testing has changed people’s lives.

This all sounds great – the promise of genomics that we have been hearing about now for about two decades. Isn’t this exactly what we were led to expect once we mapped the human genome?

Why, then, has the FDA recently sent a warning letter to 23andMe instructing them to discontinue marketing their Personal Genome Service (PGS)?

The primary reason appears to be a lack of documentation for the validity and reliability of the tests, but I have concerns that go even deeper. (more…)

Posted in: Public Health

Leave a Comment (79) →

“Postnatal depression blood test breakthrough” or Churnalism?

Postnatal depression blood test breakthrough” proclaimed the headline. The UK Guardian article then declared:

British doctors reveal ‘extremely important’ research that could help tens of thousands of women at risk.

Here it comes. Readers were going to be fed a press release generated by the study’s authors and forwarded undigested by the media but disguised as writings of a journalist.  If only the journo had asked someone in the know about the likelihood of a single study yielding such breakthrough blood test for risk of depression in new mothers.

The story echoed earlier churnalism from Sky News, British satellite television news service:

There is evidence that if you can identify women at risk early you could treat early or introduce measures to prevent or stop the process of the disease.

A study of 200 pregnant women, published in the Journal of Psychiatric Research, found two molecular “signatures” in the genes that increased the risk of postnatal depression by up to five times. One in seven new mothers suffer from depression.
(more…)

Posted in: Diagnostic tests & procedures, Science and Medicine

Leave a Comment (7) →

Thumbthing Worth Reading

I intended to read Sam Kean’s new book The Violinist’s Thumb: And Other Lost Tales of Love, War, and Genius as Written by our Genetic Code  just for fun. I was expecting a miscellany of trivia loosely gathered around the theme of DNA. But I found something much more worthwhile that I thought merited a book review to bring it to the attention of our readers. Kean interweaves entertaining stories into a somewhat disjointed but nonetheless valuable history and primer of genetics. The title refers to Paganini, whose DNA created the unusual joint flexibility that facilitated his unprecedented feats of virtuosity on the violin.

(more…)

Posted in: Basic Science, Book & movie reviews, Evolution, History

Leave a Comment (20) →

Autism and Prenatal Vitamins

Science has found no evidence that vaccines cause autism; but the true cause(s) of autism have not yet been determined. So far the available evidence has pointed towards a largely genetic cause with possible interaction with environmental factors. A new study supports that interpretation. It also supports previous evidence that autism is triggered prior to birth, rather than at the time of vaccinations.

Schmidt et al. published a study in Epidemiology on May 23, 2011, entitled “Prenatal Vitamins, One-carbon Metabolism Gene Variants, and Risk for Autism.” It was a population-based case control study of 566 subjects comparing a group of autistic children to a matched control group of children with normal development. They looked at maternal intake of prenatal vitamins in the 3 months before conception and the first month of pregnancy, and they looked for genotypes associated with autism. They found that mothers who didn’t take prenatal vitamins were at greater risk of having an autistic child, and certain genetic markers markedly increased the risk. There was a dose/response relationship: the more prenatal vitamins a woman took, the less likely she would have an autistic child. There was no association with other types of multivitamins, and no association with prenatal vitamin intake during months 2-9 of pregnancy. (more…)

Posted in: Neuroscience/Mental Health, Nutrition

Leave a Comment (71) →

The genetics of autism

Autism and autism spectrum disorders (ASDs) actually represent a rather large continuum of conditions that range from very severe neurodevelopmental delay and abnormalities to the relatively mild. In severe cases, the child is nonverbal and displays a fairly well-characterized set of behaviors, including repetitive behaviors such as “stimming” (for example, hand flapping, making sounds, head rolling, and body rocking.), restricted behavior and focus, ritualistic behavior, and compulsive behaviors. In more mild cases, less severe compulsion, restriction of behavior and focus, and ritualistic behaviors do not necessarily preclude functioning independently in society, but such children and adults may have significant difficulties with social interactions and communication. Because ASDs represent a wide spectrum of neurodevelopmental disorders whose symptoms typically first manifest themselves to parents between the ages of two and three, the idea that vaccines cause autism and ASDs has been startlingly difficult to dislodge and has fueled an anti-vaccine movement, both here in the U.S. and in other developed nations, particularly the U.K. and Australia. This movement has been stubbornly resistant to multiple scientific studies that have failed to find any link between vaccines in autism or the other favorite bogeyman of the anti-vaccine movement, the mercury-containing thimerosal preservative that used to be in many childhood vaccines in the U.S. until the end of 2001. Add to that the rising apparent prevalence of ASDs, and, confusing correlation with causation, the anti-vaccine movement concludes that vaccines must be the reason for the “autism epidemic.”

In reality, autism and ASDs appear to be increasing in prevalence due to diagnostic substition, better screening, and the broadening of the diagnostic criteria that occurred in 1994. Autism prevalence does not appear to be rising, at least not dramatically, at all, as the prevalence of ASDs, when assessed carefully, appears to be similar in adults as it is in children. If the true prevalence rate of autism and ASDs has increased, it has not increased by very much. In reality autism appears to have a major and probably predominant genetic component, and several scientific studies over the last few years have linked autism with various genetic abnormalities. Not surprisingly, given the varied presentation and severity of ASDs, these studies have not managed to identify single genes that produce autism or ASDs with a high degree of penetrance (probability of causing the phenotype if the gene is present). Indeed, one can argue that the state of current evidence is that ASDs are due to multiple genes, perhaps dozens or hundreds. Again, this is not surprising given the heterogeneity of ASD severity, presentation, and symptoms.

One of the more surprising studies supporting a genetic basis for autism appeared to much fanfare in Nature last week. The study by Pinto et al, looks at the functional impact of global rare copy number variation in autism spectrum disorders. Its results are rather surprising in that the large team of investigators (studies of this type take a lot of people to carry out) found that it may be relatively uncommon copy number variations in various genes that lead to the phenotype of autism or ASDs.
(more…)

Posted in: Neuroscience/Mental Health, Science and Medicine, Vaccines

Leave a Comment (49) →

Could Francis Collins’ Faith Create Conflicts For His Potential Directorship of NIH?

Francis Collins, M.D., Ph.D., is probably best known for his leadership of the Human Genome Project, though his discoveries of the Cystic Fibrosis, Huntington’s, and Neurofibromatosis genes are also extraordinary accomplishments. Dr. Collins is a world-renowned scientist and geneticist, and also a committed Christian. In his recent best-selling book, The Language Of God, Dr. Collins attempts to harmonize his commitment to both science and religion.

Some critics (such as Richard Dawkins) have expressed reservations about Dr. Collins’ faith, wondering if it might cloud his scientific judgment. Since Collins is rumored to be the most likely candidate for directorship of the NIH, and because I wanted to know if Dawkins et al. had any reason for concern, I decided to read The Language Of God.

First of all, Christians are a rather heterogeneous group – with a range of viewpoints on evolution, science, and the interpretation of Biblical texts. On one extreme there are Christians (often referred to as “young earth creationists” or simply “creationists”) who believe in an absolutely literal interpretation of the Genesis story, and see evolution as antithetical to true faith. Dr. Collins suggests that as many as 45% of Christians may actually be in this camp.
(more…)

Posted in: Basic Science, Book & movie reviews, Evolution

Leave a Comment (45) →