Inclusion Criteria:

• Parent-child dyads in which: child is a patient at a referring MHealth or Mayo clinic who is scheduled for clinical blood draw; child is aged between 18 and 72 months.
• Child meets criteria for a diagnosis of global developmental delay (GDD; i.e., functioning at least 2 SD below average in 2 or more domains of development).
• Has a diagnosis usually associated with GDD (e.g., Rett syndrome, Fragile X syndrome, etc.); OR
• Has been referred for suspected developmental delays; primary caregiver is 18 years of age or older; primary caregiver speaks English, Spanish, or Somali with enough fluency to complete questionnaires/interviews in that language.

Exclusion Criteria:

• Adult accompanying child to the blood draw is not the child’s primary caregiver; OR
• Is not a biological or adoptive parent with whom the child lives at least 4 days for week.
• Adoptive parents will be included only if they adopted the child within the first 12 months of the child’s life.

Note: Other protocol defined Inclusion/Exclusion Criteria may apply.

Eligibility last updated 7/18/23. Questions regarding updates should be directed to the study team contact.