4 ms·

If ADD is genetic in origin, why isn't a DNA test used to diagnose the condition?

• hyperion2010 11y ago
  Just because it is genetic (in this case they probably mean heritable and supported by twin studies) doesn't mean you can find the genes that cause it. RE: why we know that intelligence has genetic components but you will be laughed out of the room if you claim to have a genetics based IQ test.
• taco_emoji 11y ago
  A) Just because we know something is genetic (via identical twin studies, for example) doesn't mean we know which parts of the genetic sequence are responsible B) There might be a constellation of genetic polymophisms involved, such that anything short of full-genome sequencing & analysis wouldn't yield anything useful C) Even the cheapest genetic tests are likely more expensive and take longer than a 15-minute behavioral test.
• car 11y ago
  That's a good question. There are a lot of conditions where twin and adoption studies have established a genetic predispositions decades ago, but the exact cause of these disorders is unknown, and understood to be more stochastic in nature. Rather then single gene mutations, such complex disease predispositions could be combinations of single base variations in the binding sites of transcription factors and/or slight variations in proteins, which elevate disease risk, but may still require environmental factors for an actual outbreak. Our understanding here is improving rapidly, while we are learning about the regulatory elements in our genome (see the ENCODE project), and the influence of the 3D arrangement of the genome into what is known as chromatin. However, teasing apart these variations and causal relationships is extremely complex, as you can imagine. Bottom line, there is still so much we don't know or understand, but progress is being made.