Assessing social anhedonia
There are several self-report psychometric measures of schizotypy which each contain subscales related to social anhedonia:

Revised Social Anhedonia Scale—Chapman Psychosis Proneness Scales
No Close Friends Subscale – Schizotypal Personality Questionnaire
Introverted Anhedonia Subscale—Oxford–Liverpool Inventory of Feelings and Experiences

Genetic components
L.J. and J.P. Chapman were the first to discuss the possibility that social anhedonia may stem from a genetic vulnerability. The disrupted in schizophrenia 1 (DISC1) gene has been consistently associated with risk for, and cause of, schizophrenia-spectrum disorders and other mental illnesses. More recently, DISC1 has been associated with social anhedonia within the general population. Tomppo identified a specific DISC1 allele that is associated with an increase in characteristics of social anhedonia. They also identified a DISC1 allele associated with decreased characteristics of social anhedonia, that was found to be preferentially expressed in women. More research needs to be conducted, but social anhedonia may be an important intermediate phenotype (endophenotype) between genes associated with risk for schizophrenia and phenotype of the disorder. Neurobiological correlates
Researchers studying the neurobiology of social anhedonia posit that this trait may be linked to dysfunction of reward-related systems in the brain. This circuitry is critical for the sensation of pleasure, the computation of reward benefits and costs, determination of the effort required to obtain a pleasant stimulus, deciding to obtain that stimulus, and increasing motivation to obtain the stimulus.
The efforts of the "social processes" RDoC initiative will be crucial in differentiating between these components of social behavior that may underlie mental illnesses such as schizophrenia. Primary relevance in schizophrenia and schizophrenia spectrum disorders
Social anhedonia is a core characteristic of schizotypy, which is defined as a continuum of personality traits that can range from normal to disordered and contributes to risk for psychosis and schizophrenia. Social anhedonia is a dimension of both negative and positive schizotypy. It involves social and interpersonal deficits, but is also associated with cognitive slippage and disorganized speech, both of which fall into the category of positive schizotypy. Not all people with schizophrenia display social anhedonia and likewise, people who have social anhedonia may never be diagnosed with a schizophrenia-spectrum disorder if they do not have the positive and cognitive symptoms that are most frequently associated with most schizophrenia-spectrum disorders.Social anhedonia may be a valid predictor of future schizophrenia-spectrum disorders; young adults with social anhedonia perform in a similar direction to schizophrenia patients in tests of cognition and social behavior, showing potential predictive validity. Social anhedonia usually manifests in adolescence, possibly because of a combination of the occurrence of critical neuronal development and synaptic pruning of brain regions important for social behavior and environmental changes, when adolescents are in the process of becoming individuals and gaining more independence. Treatment
There is no validated treatment for social anhedonia.