Growth Hormone Treatment in Patients With Aggrecan (ACAN) Deficiency

1. ACAN Deficiency - Patients must be heterozygous for a mutation in the ACAN gene. A mutation will be defined as:

   a. A heterozygous deletion of the entire gene or of >1 complete exons of the gene b. Any truncating mutation including frameshift, nonsense, splice site mutations within 2 bases of the exon/intron boundary, and start loss variants c. Any missense mutation which meets the following criteria: i. It is absent in the Exome Aggregation Consortium Database (exac.broadinstitute.org) ii. It is predicted to be damaging by both Polyphen2 and Sorting Intolerant From Tolerant (SIFT) iii. It segregates with the short stature phenotype in the family or is a de novo mutation d. In-frame insertions or deletions of >1 amino acid e. In-frame insertions or deletions of 1 amino acid must meet the same criteria as missense mutations. For the prediction programs, Alanine will be substituted for the deleted amino acid.

   f. Note - Retrospective data does not show any correlation between the type of mutation and the severity of short stature. Therefore, all mutations meeting the above criteria will be included as a single group.

2. Age - Greater than or equal to 2 years 0 days. There is no specific upper age limit, but the onset of puberty will make the patient ineligible.

3. Pre-pubertal

   1. Male subjects must have a testicular volume \<4 cc as determined on physical examination by a pediatric endocrinologist at the time of the screening visit
   2. Female subjects must be Tanner 1 for breast development as determined on physical examination by a pediatric endocrinologist at the time of the screening visit
4. Bone Age - The bone age as determined by the Greulich and Pyle method must be equal to or greater than the chronological age. Bone ages will be determined at the screening visit by a single centralized radiologist.
5. Insulin-like growth factor (IGF-I) level within normal range for age and sex.
6. Ability to provide informed consent before any trial-related activities
7. Note - There is no specific height standard deviation criteria for inclusion in this study.

Exclusion Criteria:

1. Prior treatment with any of the following therapies:

   A. Growth hormone B. Insulin-like Growth Factor (IGF-I) C. Gonadotropin releasing hormone (GnRH) analog D. Aromatase Inhibitor E. Oxandrolone

2. History of any type of malignancy
3. Growth plate fusion - Defined as a bone age via the Greulich and Pyle method of 13 years in females and 15 years in males

4. Chronic medical condition known to affect growth including but not limited to:

   A. Cystic fibrosis B. Diabetes C. Inflammatory Bowel Disease D. Celiac Disease E. Asthma requiring a daily inhaled steroid dose > 400 micrograms of inhaled budesonide per day or equivalent F. Taking daily oral glucocorticoids for any reason G. Note - attention deficit hyperactivity disorder (ADHD) treated with a stimulant and treated hypothyroidism with a normal thyroid stimulating hormone (TSH) will not exclude the subject from participating in the trial.

5. (BMI) \<5th percentile (CDC growth charts)
6. Any clinically significant abnormality on screening laboratory tests as determined by the principal investigator.
7. Known or suspected allergy to trial medication, excipients, or related products.
8. Contraindications to study medications, worded specifically as stated in the product's prescribing information.
9. The receipt of any investigational drug within 90 days prior to this trial.