lunes, 28 de julio de 2014

Guidelines for genome-sequencing tests for kids - Stanford Medicine Newsletter - Stanford University School of Medicine

Guidelines for genome-sequencing tests for kids - Stanford Medicine Newsletter - Stanford University School of Medicine

Genomics & Health Impact Update

Birth Defects & Child Health

Stanford Medicine

Guidelines for genome-sequencing tests for kids

Curiosity, a family history of illness, or the simple notion that knowledge is power may motivate parents to purchase whole-genome sequencing tests for themselves or their children. But, as Louanne Hudgins, MD, chief of medical genetics and director of perinatal genetics at Lucile Packard Children’s Hospital Stanford, explained, there are unique risks to these direct-to-consumer tests for children.
“I strongly advise parents against whole-genome testing for their children unless performed in the context of a medical evaluation following formal counseling regarding its utility, limitations and possible unrelated findings,” said Hudgins, a professor of pediatrics and of medical genetics at Stanford School of Medicine.
While whole-genome testing has the potential to pin down countless details — from our hair and eye color to our risk for certain diseases — it may also reveal mysteries we cannot solve, surprise us with information we don’t want, create undue anxiety and expose our private health information. Screening for specific disorders has become routine in pregnancy, and newborn genetic screening can identify certain conditions that are difficult or impossible to detect any other way.
But personal genome sequencing is not specific. It gathers all genetic data into one enormous report, with little or no context. Buyers are presented with a trove of genetic information that may be difficult to understand and possibly difficult to cope with.
For parents who may want to purchase direct-to-consumer whole-genome testing, Hudgins encourages careful consideration of the following issues, as well as those outlined in the American College of Medical Genetics Statement on Direct-to-Consumer Genetic Testing, which she co-authored.
  • Genome tests often identify sequence variants associated with adult-onset disorders. While this knowledge may assist with medical care in adulthood, it could be a profound and premature psychological burden to parents and children. It also fails to honor the autonomy of children—their right to decide whether they want information about their future health revealed.
  • If your child is healthy, it’s worth questioning your motivations to test. Consider what you are looking for, and why. “In a healthy child,” said Hudgins, “you’re more likely to find inconclusive results that will cause you unnecessary anxiety.” For children with symptoms or undiagnosed diseases, Hudgins suggests working directly with a medical care provider who understands the utility and limitations of the testing and who can interpret the results.
  • Consider the long-term privacy of your child’s (and your own) health information. Who will have access to the results of your child’s test, and how will those results be used? Companies’ privacy policies vary widely and can change over time, potentially leading to exposure of your child’s private health information. Some direct-to-consumer genome testing companies reserve the right to use the personal health information that they gather during testing.
  • Genome tests are likely to identify “sequence variants of unknown significance.” Results may depend on the family’s medical history or other factors to be conclusive, or may depend on future research that produces unexpected or unwanted results or which may never be conclusive. Most doctors prefer to do specific genetic testing for patients based on known risk factors.
  • A sequence variant of unknown significance in a child may be a signal to look at the genetic sequence of the parents, which can sometimes lead to surprises for the family. Hudgins explained that it is not uncommon to discover situations of nonpaternity (mistaken fatherhood) or even to identify instances of homozygosity — when parents turn out to be related by blood.
  • Whole-genome tests may reveal that your child has a change in a gene predisposing him or her to a disease, such as autism. “This does not mean that your child will become autistic,” said Hudgins. “It means that in large population studies, specific changes in that gene were associated with an increased risk of autism. But it is not a guarantee, as expression of each gene is influenced by a variety of individual factors.” While some results may provoke unfounded worry, others may provide false reassurance.
  • Most direct-to-consumer genome tests do not have genetic counselors available to interpret results, leaving parents with an enormous amount of information about their child that they cannot interpret on their own. Research-quality testing, interpretation and analysis can take up to 100 hours and cost around $17,000 per person, according to a recent study by Stanford scientists published in the Journal of the American Medical Association. The study also showed that the current technology used for whole-genome sequencing is not yet as accurate as it needs to be.
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