Haploinsufficiency of autism causative gene Tbr1 impairs olfactory discrimination and neuronal activation of the olfactory system in mice.
Tzyy-Nan Huang, Tzu-Li Yen, Lily R Qiu and 3 others
PMID 30792833WHAT IT FOUND
In mice with one copy of the autism-linked Tbr1 gene removed, detecting and getting used to a smell were normal, but telling a new smell from a familiar one was impaired.
A drug called D-cycloserine given before testing improved discrimination in these mice.
Key findings
01Of the 11 Tbr1 +/− mice assayed, only five spent more time sniffing 2-heptanol, and their odor preference index was significantly lower.
02Olfactory sensation and habituation were normal in Tbr1 +/− mice, while discrimination of 2-heptanol from limonene was impaired.
03D-cycloserine treatment improved olfactory discrimination in Tbr1 +/− mice.
STILL TO COME
How it was doneWhat they found
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What it does not show
This is a mouse study, so it does not show what happens in patients. The paper does not state the total number of mice analysed; it only says 11 mutant mice were assayed in the discrimination test. No statistical method was applied to evaluate sample size. Only male mice were used, so results may not apply to females. The paper does not report human olfactory or behavioral outcomes, so it cannot support clinical recommendations. The authors say more detailed analysis is required to fully understand the circuit defects.
Declared interests
Funded by Academia Sinica, the Ministry of Science and Technology of Taiwan, and the Ontario Brain Institute. The supplied text does not report a conflict of interest statement.
The easy way to misread this
Do not read the D-cycloserine result as evidence that this drug improves smell or autism symptoms in people. The study tested mice with a specific genetic mutation, not patients, and did not measure human clinical outcomes.