Behavioral testing is the gold standard for diagnosing autism spectrum disorder (ASD). These tests, including ADOS and ADI-R, are subjective, require trained staff to administer, are time-consuming, and can only be administered at a later age. Blood-, urine- or stool-based diagnostic biomarker test for ASD would enable objective early diagnosis, potentially even before clinical symptoms are present, eliminate the need for trained staff and enable early intervention. Such a test would not only conserve money and time but would also provide clues to ASD pathogenesis.

To date, no definitive treatment exists for ASD. Most therapies are symptom-focused, generally focusing on behavioral, social and communication skills. Recent works have reported on promising outcomes of mesenchymal stem cell (MSC) treatment of children with ASD. MSCs are multipotent, non-hematopoietic, easily isolatable and expandable stem cells involved in tissue repair, immunomodulatory responses and neuromodulation. MSC treatment of children with ASD has reportedly led to improvements in speech, sociability, eye coordination, balance, cognition and overall well-being. At the base of this approach lies the known plasticity of the human brain and immune system in the early childhood years and the ability of MSCs to modulate atypical inflammatory and immune activities. Assessment of ASD biomarker profiles in children with ASD who have undergone one or more SCT sessions may shed light on the mechanism of action, assist in better defining ASD-specific diagnostic markers and monitor treatment outcomes.

There is accumulating evidence that at least a subset of children diagnosed with ASD also have aberrant immune functions. This study will attempt to identify more specifically the nature of the potential immune abnormalities in children.

The study will follow a case-control design, involving the following cohorts:

1. young children (2-12 years) diagnosed with ASD
2. children (12-18 years) diagnosed with ASD
3. age- and sex-matched typically developing children
4. high-risk infants (10-19 months) with at least one sibling with diagnosed ASD
5. mothers of these high-risk infants
6. young children (2-12 years) diagnosed with ASD and scheduled to undergo stem cell transplantation therapy (SCT)

Parents will be asked to complete several questionnaires relating to demographic and anamnestic details and to the child's development.

• A single blood draw from all participants will be performed in the clinic.

• A stool sample will be collected from high-risk infants.

• A stool and urine sample will be collected at home from children due to undergo SCT. For children scheduled to undergo SCT, the blood, stool and urine samples must be collected before therapy.

  • Parents of high-risk infants will be contacted by phone or email when the child reaches diagnosable age (3.5 years) and again at the age of 6 years, to obtain an update on the child's ASD status. If the child has been diagnosed with ASD, an additional blood and stool sample may be collected.
  • Children who underwent SCT will be contacted 2±1 months and 6±1 months after the first treatment session, for collection of additional blood samples. Stool and urine samples will be collected at the 6±1 month post-treatment visit as well. Should the child undergo additional SCT within two years of the first treatment, additional blood, stool and urine samples may be collected. At each subsequent visit, a parent/legal guardian will be asked to complete several short questionnaires.

Adverse events to blood drawing will be reported to the Data Coordinating Center using the appropriate Case Report Form (CRF).

In cases of adverse effects (AE) related to the drawing of blood or performance of examination of patients in the course of standard examination procedures, the investigating team will proceed in accordance with local guidelines (to be inserted by the PI), reporting the incidents which occurred during the course of a clinical trial.

Clinical data will be collected by the investigator, or a person appointed and appropriately trained by the investigator, and shall be entered into standardized CRFs and shared online with the sponsor. Source data will be retained for all data entered in the CRFs. Progress reports and the Final Report at the conclusion of the trial will be submitted to the regulatory authority and the Ethics Committee, as required.

Inclusion Criteria:

1. Male and female children
2. Child aged 2-12 years with diagnosed ASD according to Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV (299.00) or DSM-V (299.00) OR Child aged 2-18 years diagnosed ASD according to DSM-IV (299.00) or DSM-V (299.00) AND scheduled to undergo stem cell transplantation OR Child aged 10-19 months not diagnosed with ASD but with a sibling diagnosed with ASD according to (DSM)-IV (299.00) or DSM-V (299.00) (herein termed "high-risk infants") OR Mothers of recruited high-risk infants OR A typically developing child aged 2-12 years with no signs of ASD or history of ASD in the immediate family
3. Informed consent signed by the parent/legal guardian

Exclusion Criteria:

1. Child and/or mother completed treatment with systemic steroids or immune suppressants less than 4 weeks before the screening visit
2. Child and/or mother diagnosed with severe infectious diseases or sepsis over the last 6 months
3. Child with ASD treated for a severe convulsive disorder (intractable seizures)
4. Child and/or mother with hematological or malignant disorder
5. For children in the SCT cohort: No new planned immune-modulating treatment (other than SCT) for at least 6 months before or after planned stem cell transplantation date
6. If the PI suspects that the participant will not comply with study requirements, the participant may be excluded.

1. Up to a total of 350 male and female children, aged 2-12 years, diagnosed with ASD according to DSM-IV (299.00) or DSM-V (299.00)
2. Up to a total of 350 male and female typically developing (TD) children aged 2-12 years with no signs of ASD or history of ASD in the immediate family who will serve as controls for the main subset of children with ASD
3. Up to 50 infants aged 10-19 months not diagnosed with ASD but with a sibling diagnosed with ASD according to DSM-IV (299.00) or DSM-V (299.00) (herein, high-risk infants)
4. Up to 50 mothers of the high-risk infants participating in the study
5. Up to 50 male and female children, aged 2-12 years, diagnosed with ASD according to DSM-IV (299.00) or DSM-V (299.00) scheduled to undergo stem cell therapy (SCT)
6. Up to 50 male and female children, aged 12-18 years, diagnosed with ASD according to DSM-IV (299.00) or DSM-V (299.00) scheduled to undergo SCT