Early Treatment of Language Impairment in Young Children with Autism Spectrum Disorder with Leucovorin Calcium

1. Autism Spectrum Disorder (as defined below).

2. Between 2 years 6 months and 5 years 2 months of age at baseline

3. Language impairment (Ages and Stage Questionnaire between -1 and -3 SD for Language)

4. Has at least 4 month old expressive language ability as assessed by the MSEL Expressive Language Scale (i.e., Parent answers "yes" to " Voluntary babbling (such as 'bu, bu, bu")" Question #7 on the MSEL Expressive Language Scale.

5. English included in the languages in which the child is being raised

6. Autism severity of moderate or higher (≥4) under the 7-item clinical global impression-severity scale. Moderate level of autism severity (4) is defined by the diagnosis of ASD with language impairment, so fulfilling #1 and #4 fulfills this requirement.

6. Ability to maintain all ongoing complementary, dietary, traditional, and behavioral treatments constant for the study period 7. Unchanged complementary, dietary, traditional, and behavioral treatments for two months prior to study entry

1. Known FRAA status by clinically validated test performed outside of research studies.

2. Mineral or vitamin supplementation that exceeds the Tolerable Upper Daily Intake Levels set by the Institute of Medicine (See Table 5 below)

3. Significant self-abusive or violent behavior or evidence of suicidal ideation, plan or behavior

4. Severely affected as defined by CGI-Severity Standard Score = 7 (Extremely Ill)

5. Severe prematurity (<34 weeks gestation) as determined by medical history

6. Current uncontrolled gastroesophageal reflux

7. Current or history of liver or kidney disease as determined by medical history and safety labs

8. Genetic syndromes

9. Congenital brain malformations

10. Epilepsy

11. Any medical condition that the PI determines could jeopardize the safety of the study subject or compromise the integrity of the data

12. Significant negative reaction (i.e. fainting, vomiting, etc.) because of a previous blood draw.

13. Failure to thrive or Body Mass Index < 5%ile or <5%ile for weight (male <11.2kg; female <10.8kg by CDC 2000 growth charts) at the time of screening.

14. Concurrent treatment with drug that would significantly interact with l-leucovorin such as specific chemotherapy agents, antimalarial and immune suppressive agents and select antibiotics (See Table 6 below).

15. Allergy or Sensitivity to ingredients in the investigational product or placebo

16. Evaluation with the MSEL or BOSCC within 3 months of entering the study

17. Planned evaluation with the MSEL or BOSCC during the study