The goal of this study was to develop an empirically derived classification system for selective mutism (SM) using parent-report measures of social anxiety, behavior problems, and communication delays. The sample consisted of parents of 130 children (ages 5-12) with SM. Results from latent profile analysis supported a 3-class solution made up of an anxious-mildly oppositional group, an anxious-communication delayed group, and an exclusively anxious group. Follow-up tests indicated significant group differences on measures of SM symptom severity, externalizing problems, and expressive/receptive language abilities. These results suggest that, although social anxiety is typically a prominent feature of SM, children with the disorder are also likely to present with communication delays and/or mild behavior problems.

Background Selective mutism (SM), considered an early-onset variant of social anxiety disorder (SAD), shares features of impaired social interaction and communication with autism spectrum disorders (ASDs) that suggest a possible shared pathophysiology. We examined the association of a susceptibility gene, contactin-associated protein-like 2 (CNTNAP2), for ASDs and specific language impairment (SLI) with SM and social anxiety-related traits. Methods Sample 1 subjects were 99 nuclear families including 106 children with SM. Sample 2 subjects were young adults who completed measures of social interactional anxiety (SIAS; N = 1028) and childhood behavioral inhibition (RSRI; N = 920). Five SNPs in CNTNAP2 (including rs7794745 and rs2710102, previously associated with ASDs) were genotyped. Results FBAT analyses revealed nominal significance (p = 0.018) for association of SM with rs2710102 which, with rs6944808, was part of a common haplotype associated with SM (permutation p = 0.022). Adjusting for sex and ancestral proportion, each copy of the rs2710102*a risk allele in the young adults was associated with increased odds of being >1SD above the mean on the SIAS (OR = 1.33, p = 0.015) and RSRI (OR = 1.40, p = 0.010). Discussion Although association was found with rs2710102, the risk allele (“a”) for the traits studied here is the non-risk allele for ASD and SLI (“g”). These findings suggest a partially shared etiology between ASDs and SM, but raise additional questions about specific aspects of these syndromes (i.e., language impairment and/or social anxiety) potentially influenced by CNTNAP2 and mechanism(s) by which these influences may be conveyed.

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Objective-To evaluate the factor structure, reliability, and validity of the 17-item Selective Mutism Questionnaire.Method-Diagnostic interviews were administered via telephone to 102 parents of children identified with selective mutism (SM) and 43 parents of children without SM from varying U.S. geographic regions. Children were between the ages of 3 and 11 inclusive and comprised 58% girls and 42% boys. SM diagnoses were determined using the Anxiety Disorders Interview Schedule for Children -Parent Version (ADIS-C/P); SM severity was assessed using the 17-item Selective Mutism Questionnaire (SMQ); and behavioral and affective symptoms were assessed using the Child Behavior Checklist (CBCL). An exploratory factor analysis (EFA) was conducted to investigate the dimensionality of the SMQ and a modified parallel analysis procedure was used to confirm EFA results. Internal consistency, construct validity, and incremental validity were also examined.Results-The EFA yielded a 13-item solution consisting of three factors: a) Social Situations Outside of School, b) School Situations, and c) Home and Family Situations. Internal consistency of SMQ factors and total scale ranged from moderate to high. Convergent and incremental validity were also well supported.Conclusions-Measure structure findings are consistent with the 3-factor solution found in a previous psychometric evaluation of the SMQ. Results also suggest that the SMQ provides useful and unique information in the prediction of SM phenomenon beyond other child anxiety measures.