Williams Syndrome (WS) is a rare neurodevelopmental disorder, usually caused by microdeletions of approximately 26 genes in the long arm (7q11.23) region of chromosome 7. Children with this syndrome often exhibit distinctive facial features, mild to moderate intellectual disability, impaired spatial cognition, pronounced social extraversion, and relatively reserved language-expression characteristics. Although individuals with WS often demonstrate strong social interest and prosocial behaviors, significant deficiencies in abstract thinking, executive function, and visuospatial ability are frequently observed. At present, treatment for WS mainly focuses on behavioral intervention and educational rehabilitation, and clear molecular or pharmacological treatment methods remain limited. Due to the "opposite but related" social-cognitive profile observed in comparison with autism spectrum disorder, in-depth exploration of neural and molecular mechanisms underlying these differences has substantial scientific significance for understanding the biological basis of social-cognitive impairment.

Participants for Williams Syndrome Study

Inclusion criteria must all be met:

1. Age 3-12 years old.
2. Clinically diagnosed and confirmed by fluorescence in situ hybridization (FISH) test, with a typical microdeletion of approximately 1.55 Mb in the chromosome 7q11.23 region.
3. Their legal guardians fully understand the study content and voluntarily sign the informed consent form, agreeing for the study participants to undergo blood sampling and genetic testing.

Participants for Autism Spectrum Disorder Study

Inclusion criteria must all be met:

1. Age 3-12 years old.
2. Clinically diagnosed according to the second edition of the Autism Diagnostic Observation Schedule (ADOS-2) criteria.
3. Their legal guardians fully understand the study content and voluntarily sign the informed consent form, agreeing for the study participants to undergo blood sampling and genetic testing.

Participants for Healthy Children Study

Inclusion criteria must all be met:

1. Age 3-12 years old, with gender as close as possible to the participants in the above two groups.
2. No history of neurodevelopmental disorders, mental illnesses or major neurological diseases.
3. Their legal guardians fully understand the study content and voluntarily sign the informed consent form, agreeing for the study participants to undergo blood sampling and genetic testing.

Common Exclusion Criteria for All Study Participants

Any of the following conditions must be met to be excluded from the study:

1. Specific medical conditions:
2. For the Williams Syndrome group: Known or suspected presence of other pathogenic gene mutations/syndromes other than the 7q11.23 microdeletion.
3. For the Autism Spectrum Disorder group: Co-occurring other clearly diagnosed neurodevelopmental disorders (such as Rett syndrome, fragile X syndrome, etc.).
4. Brain structural abnormalities: According to recent cranial MRI and interpretation by neuro-radiology experts, significant brain structural lesions are found (for the patient group, referring to lesions unrelated to Williams Syndrome or autism; for the healthy group, referring to any clinically significant abnormalities).
5. Major systemic diseases: Presence of diseases with clinical significance as judged by the researchers, which may: affect the interpretation of study results, or endanger the safety of the study participants.

Source of research participants: WS research participants, ASD research participants and normal children controls who visited the pediatric health rehabilitation clinic