Social behavior is the evolutionary foundation of our complex society and culture but its genetic basis is still an enigma [
1]. One of the greatest scientific challenges in modern neuroscience is to unveil the mystery of the social genetic basis of social behaviors. As social behaviors are widely observed in the animal kingdom, and their patterns share many similarities across species, it is desirable to elucidate the evolutionary conserved genetic bases of social behaviors [
2]. In humans, impaired social reciprocity is one of the core symptoms of autism [
3] and aggressive behavior, which is a manifestation of social dysfunction frequently observed in individuals with autism [
4]. Genetic epidemiological studies have already demonstrated that autism has a definitely strong genetic basis [
5]. Pinpointing the genes that are critical for social behaviors will not only improve our scientific knowledge but also shed light on targets for clinical intervention for patients with autism. Recently, several large-scale human genetic studies have clearly demonstrated that mutations of synaptic proteins can lead to social dysfunctions [
6‐
9]. Synapses, across which neurons transmit, exchange and process information, are the building bricks of our mental function. A specialized group of synaptic macromolecules, the postsynaptic scaffolding proteins, which play a role as the master organizers of macromolecular assembly within the postsynaptic density (PSD), is pivotal to proper synaptic functions [
10,
11]. DLGAP2 (also known as SAPAP2 or GKAP2), as one of the main components of postsynaptic scaffolding proteins, directly interacts with DLG4 (also known as PSD-95) and SHANKs to form the DLG4-DLGAPs-SHANKs complex, which plays critical roles in synaptic morphogenesis and functions [
12‐
14]. Human genetic studies point out that mutations of synaptic scaffold proteins may contribute to the etiology of psychiatric and neurodevelopmental disorders [
15,
16]. Further,
DLG4[
17],
SHANKs[
18‐
20] and
DLGAP2[
8,
21,
22] have been listed as possible candidate genes for autism. According to the findings of Pinto
et al.,
DLGAP2 was encompassed in rare
de novo copy number variations, which were not found in the control group [
8]. In our previous study of copy number variation, we also identified a patient carrying a
de novo 8p23.2-pter microdeletion, which encompasses
DLGAP2[
23]. Several genetically manipulated mouse models have been used to demonstrate successfully that disruptions of
Dlg4[
17] and
Shanks[
24‐
27] can lead to abnormalities in social behaviors. However, the role of
Dlgap2 still remains elusive, which intensifies our eagerness to unveil whether
Dlgap2 regulates social behaviors or synaptic functions.