GABAB-GIRK2-mediated signaling in Down syndrome.

Down syndrome (DS) results from the presence of an extra copy of genes on the long-arm of chromosome 21. Aberrant expression of these trisomic genes leads to widespread neurological changes that vary in their severity. However, how the presence of extra genes affects the physiological and behavioral phenotypes associated with DS is not well understood. The most likely cause of the complex DS phenotypes is the overexpression of dosage-sensitive genes. However, other factors, such as the complex interactions between gene products as proteins and noncoding RNAs, certainly play significant roles contributing to the spectrum of severity. Here we will review evidence regarding how the overexpression of one particular gene encoding for G-protein-activated inward rectifying potassium type 2 (GIRK2) channel subunit and its coupling to GABA(B) receptors may contribute to a range of mental and functional disabilities in DS.