By creating genetically engineered fish, two independent groups have identified genes in an autism hotspot on chromosome 16 that influence head size and brain development. One of the studies appears today in Nature.
A 29-gene stretch of chromosome 16 known as 16p11.2, or 16p, is deleted or duplicated in roughly one percent of individuals with autism and duplicated in some individuals with schizophrenia. Researchers have struggled to sort out which genes in the region contribute to features of these disorders.
Using zebrafish allows for an unbiased screen of individual genes, says Nicholas Katsanis, professor of cell biology at Duke University in Durham, North Carolina, and lead investigator of the Nature study. “We tested all of them with exactly same protocol, with no prior expectation of what we were going to find,” he says.
His study shows that suppressing a little-known gene called KCTD13 in zebrafish leads to a 20 percent increase in head size. Conversely, expressing too much of the gene leads to a 20 percent decrease in head size.
This seems to mirror what happens in people. Individuals lacking one copy of 16p often have abnormally large heads, dubbed macrocephaly, whereas those with an extra copy tend to have abnormally small heads, or microcephaly.
Read more at…
Children with autism carry twice as many new and damaging genetic mutations as typically developing children, according to a large study published today in Neuron.
Several hundred genes are likely involved in autism, according to the latest 
In spring 2007, half-a-dozen scientists huddled around a laptop at a pub in Cambridge in the United Kingdom, to see the preliminary results from the largest ever genetic study of multiple sclerosis (MS). Expectations were high. Three decades had passed since the last genes were discovered to have a link to MS, in a large genomic region called the major histocompatibility complex (MHC).
It’s been almost a year 
For most animals, the number of males in a population is about the same as the number of females. And that makes sense, evolutionarily. If a population were skewed toward females, for instance, males would become a hot commodity and each one would have a better chance of mating than would a male in a balanced population. Eventually, parents who had boys would accumulate more grandchildren, and the genes for producing boys would spread until the sex ratio evened out.
Nature, for all of its free-wheeling weeds and lightning strikes, is also full of biological regularity: the rows of an alligator’s teeth, the stripes on a zebrafish, the spacing of a chicken’s feathers. How do these patterns arise?
