Dataset Information

Delineation of the genetic and clinical spectrum of Phelan-McDermid syndrome caused by SHANK3 point mutations.

ABSTRACT: Background:Phelan-McDermid syndrome (PMS) is a neurodevelopmental disorder characterized by psychiatric and neurological features. Most reported cases are caused by 22q13.3 deletions, leading to SHANK3 haploinsufficiency, but also usually encompassing many other genes. While the number of point mutations identified in SHANK3 has increased in recent years due to large-scale sequencing studies, systematic studies describing the phenotype of individuals harboring such mutations are lacking. Methods:We provide detailed clinical and genetic data on 17 individuals carrying mutations in SHANK3. We also review 60 previously reported patients with pathogenic or likely pathogenic SHANK3 variants, often lacking detailed phenotypic information. Results:SHANK3 mutations in our cohort and in previously reported cases were distributed throughout the protein; the majority were truncating and all were compatible with de novo inheritance. Despite substantial allelic heterogeneity, four variants were recurrent (p.Leu1142Valfs*153, p.Ala1227Glyfs*69, p.Arg1255Leufs*25, and c.2265+1G>A), suggesting that these are hotspots for de novo mutations. All individuals studied had intellectual disability, and autism spectrum disorder was prevalent (73%). Severe speech deficits were common, but in contrast to individuals with 22q13.3 deletions, the majority developed single words, including 41% with at least phrase speech. Other common findings were consistent with reports among individuals with 22q13.3 deletions, including hypotonia, motor skill deficits, regression, seizures, brain abnormalities, mild dysmorphic features, and feeding and gastrointestinal problems. Conclusions:Haploinsufficiency of SHANK3 resulting from point mutations is sufficient to cause a broad range of features associated with PMS. Our findings expand the molecular and phenotypic spectrum of PMS caused by SHANK3 point mutations and suggest that, in general, speech impairment and motor deficits are more severe in the case of deletions. In contrast, renal abnormalities associated with 22q13.3 deletions do not appear to be related to the loss of SHANK3.

SUBMITTER: De Rubeis S

PROVIDER: S-EPMC5921983 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Delineation of the genetic and clinical spectrum of Phelan-McDermid syndrome caused by <i>SHANK3</i> point mutations.

De Rubeis Silvia S Siper Paige M PM Durkin Allison A Weissman Jordana J Muratet François F Halpern Danielle D Trelles Maria Del Pilar MDP Frank Yitzchak Y Lozano Reymundo R Wang A Ting AT Holder J Lloyd JL Betancur Catalina C Buxbaum Joseph D JD Kolevzon Alexander A

Molecular autism 20180427

<h4>Background</h4>Phelan-McDermid syndrome (PMS) is a neurodevelopmental disorder characterized by psychiatric and neurological features. Most reported cases are caused by 22q13.3 deletions, leading to <i>SHANK3</i> haploinsufficiency, but also usually encompassing many other genes. While the number of point mutations identified in <i>SHANK3</i> has increased in recent years due to large-scale sequencing studies, systematic studies describing the phenotype of individuals harboring such mutation ...[more]

PMID: 29719671

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Project description:Mutations in the SHANK3 gene have been discovered in autism spectrum disorder (ASD), and the intellectual disability, Phelan-McDermid Syndrome. This study leveraged a new rat model of Shank3 deficiency to assess complex behavioral phenomena, unique to rats, which display a richer social behavior repertoire than mice. Uniquely detectable emissions of ultrasonic vocalizations (USV) in rats serve as situation-dependent affective signals and accomplish important communicative functions. We report, for the first time, a call and response acoustic playback assay of bidirectional social communication in juvenile Shank3 rats. Interestingly, we found that Shank3-deficient null males did not demonstrate the enhanced social approach behavior typically exhibited following playback of pro-social USV. Concomitantly, we discovered that emission of USV in response to playback was not genotype-dependent and emitted response calls were divergent in meaning. This is the first report of these socially relevant responses using a genetic model of ASD. A comprehensive and empirical analysis of vigorous play during juvenile reciprocal social interactions further revealed fewer bouts and reduced durations of time spent playing by multiple key parameters, including reduced anogenital sniffing and allogrooming. We further discovered that male null Shank3-deficient pups emitted fewer isolation-induced USV than Shank3 wildtype controls. Postnatal whole brain anatomical phenotyping was applied to visualize anatomical substrates that underlie developmental phenotypes. The data presented here lend support for the important role of Shank3 in social communication, the core symptom domain of ASD. By increasing the number of in vivo functional outcome measures, we improved the likelihood for identifying and moving forward with medical interventions. Autism Res 2018, 11: 587-601. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY:Clinically relevant outcomes are required to demonstrate the utility of therapeutics. We introduce findings in a rat model, and assess the impact of mutations in Shank3, an autism risk gene. We found that males with deficient expression of Shank3 did not demonstrate typical responses in a bi-directional social communication test and that social interaction was lower on key parameters. Outcome measures reported herein extend earlier results in mice and capture responses to acoustic calls, which is analogous to measuring receptive and expressive communication.

Project description:BackgroundPhelan-McDermid syndrome (PMS) is a neurodevelopmental disorder associated with a terminal deletion affecting chromosome 22 (22q13) that results in the loss of function of the SHANK3 gene. SHANK3 has also been identified in gene-linkage studies to be associated with autism spectrum disorder (ASD). Diagnosis of ASD in individuals with PMS is complicated by the presence of moderate to profound global developmental delay/intellectual disability as well as other co-morbid systemic and neurological symptoms.MethodsThe current study aimed to characterize the symptoms of ASD in patients with PMS and to do a preliminary exploration of genotype-ASD phenotype correlations. We conducted a standardized interview with 40 parents/guardians of children with PMS. Further, we conducted analyses on the relationship between disruption of SHANK3 and adjacent genes on specific characteristic symptoms of ASD in PMS in small subset of the sample.ResultsThe majority of PMS participants in our sample displayed persistent deficits in Social communication, but only half met diagnostic criteria under the restricted, repetitive patterns of behavior, interests, or activities domain. Furthermore, logistic regressions indicated that general developmental delay significantly contributed to the ASD diagnosis. The analyses relating the PMS genotype to the behavioral phenotype revealed additional complex relationships with contributions of genes in both deleted and preserved SHANK3 regions to the ASD phenotype and other neurobehavioral impairments.ConclusionsThere appears to be a unique behavioral phenotype associated with ASD in individuals with PMS. There also appears to be contributions of genes in both deleted and preserved SHANK3 regions to the ASD phenotype and other neurobehavioral impairments. Better characterization of the behavioral phenotype using additional standardized assessments and further analyses exploring the relationship between the PMS genotype and behavioral phenotype in a larger sample are warranted.

Project description:Phelan-McDermid syndrome (PMS) is a rare genetic disorder in which one copy of the SHANK3 gene is missing or mutated, leading to a global developmental delay, intellectual disability (ID), and autism. Multiple intragenic promoters and alternatively spliced exons are responsible for the formation of numerous isoforms. Many genetically-modified mouse models of PMS have been generated but most disrupt only some of the isoforms. In contrast, the vast majority of known SHANK3 mutations found in patients involve deletions that disrupt all isoforms. Here, we report the production and thorough behavioral characterization of a new mouse model in which all Shank3 isoforms are disrupted. Domains and tasks examined in adults included measures of general health, neurological reflexes, motor abilities, sensory reactivity, social behavior, repetitive behaviors, cognition and behavioral inflexibility, and anxiety. Our mice are more severely affected than previously published models. While the deficits were typically more pronounced in homozygotes, an intermediate phenotype was observed for heterozygotes in many paradigms. As in other Shank3 mouse models, stereotypies, including increased grooming, were observed. Additionally, sensory alterations were detected in both neonatal and adult mice, and motor behavior was strongly altered, especially in the open field and rotarod locomotor tests. While social behaviors measured with the three-chambered social approach and male-female interaction tests were not strongly impacted, Shank3-deficient mice displayed a strong escape behavior and avoidance of inanimate objects in novel object recognition, repetitive novel object contact, marble burying, and nest building tasks, indicating increased novelty-induced anxiety. Similarly, increased freezing was observed during fear conditioning training and amygdala-dependent cued retrieval. Finally, deficits were observed in both initial training and reversal in the Barnes maze and in contextual fear testing, which are memory tasks involving hippocampal-prefrontal circuits. In contrast, working memory in the Y-maze spontaneous alternation test was not altered. This new mouse model of PMS, engineered to most closely represent human mutations, recapitulates core symptoms of PMS providing improvements for both construct and face validity, compared to previous models.

Dataset Information

Delineation of the genetic and clinical spectrum of Phelan-McDermid syndrome caused by SHANK3 point mutations.

Publications

Delineation of the genetic and clinical spectrum of Phelan-McDermid syndrome caused by <i>SHANK3</i> point mutations.

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