Patient description: A 5 months old male brought to the pediatrics surgery clinic with the complaint of empty scrotum at the right side. The baby boy is a first child who was born at the age of 38 weeks with NVD from a healthy mother. The mother had a normal pregnancy with no complication. The baby boy weighted 3200 gr with the height of 50 cm. He is breast feeding and now weighted as 6.5 kg with the height of 62 cm. He has no developmental delay in the physical assessment. There is a palpable testis is the left scrotum with non-palpable testis in the right scrotum. The penis is normal in shape and size and he is not circumcised. The diagnostic laparoscopy showed an abdominal undescended testis.

Clinical trial eligibility criteria: eligible ages (years): 0.0-6.0,  Hunter Syndrome Group 1: Prospective Patient Group 1. The patient is male. 2. The patient is Elaprase-naïve at study entry. 3. The patient must have a documented diagnosis of MPS II. Of the 3 below, the combinations (3a AND 3b) or (3a AND 3c) will be accepted as diagnostic of MPS II: 1. The patient has a deficiency in I2S enzyme activity of ≤10% of the lower limit of the normal range as measured in plasma, fibroblasts, or leukocytes (based on the reference laboratory's normal range). AND 2. The patient has a documented mutation in the I2S gene. OR 3. The patient has a normal enzyme activity level of one other sulfatase as measured in plasma, fibroblasts, or leukocytes (based on the normal range of measuring laboratory). 4. The patient will be <6 years of age at the start of Elaprase treatment. 5. The patient, patient's parent(s) or legally authorized guardian(s) must have voluntarily signed an Institutional Review Board (IRB)/Independent Ethics Committee (IEC) approved informed consent form after all relevant aspects of the study have been explained and discussed. Consent of the patient's parent(s) or legally authorized guardian(s) and the patient's assent, as relevant, must be obtained. Group 2: Retrospective Data Retrospective Patient Group patients will be enrolled in HOS and not Study SHP-ELA-401; however, their growth data may be included in the analysis for Study SHP-ELA-401 if the following data are met. 1. The patient is male. 2. The patient is enrolled in HOS. 3. The patient was <6 years of age at the start of Elaprase treatment. 4. The patient received Elaprase weekly treatment for at least 5 years. 5. The patient had a height assessment and a weight assessment documented within 3 months before or after Elaprase treatment start. 6. The patient has had annual height and weight assessments from start of Elaprase through age 10 years. 7. The patient, patient's parent(s), or legally authorized guardian(s) agree(s) to data collection. 8. The patient, patient's parent(s), or legally authorized guardian(s) must have signed an IRB/IEC-approved informed consent form after all relevant aspects of the HOS study have been explained and discussed. Consent of the patient's parent(s) or legally authorized guardian(s) and the patient's assent, as relevant, must be obtained  Group 1: Prospective Patient Group 1. The patient has received treatment with any investigational drug or device within the 30 days prior to study entry. 2. The patient has received or is receiving treatment with idursulfase-IT. 3. The patient has received growth hormones, a cord blood infusion, or a bone marrow transplant at any time. 4. The patient has received blood product transfusions within 90 days prior to Screening. 5. The patient is unable to comply with the protocol as determined by the Investigator. Group 2: Retrospective Data HOS patients that meet the following are not eligible to be included into the Study SHP-ELA-401 Primary Growth Analysis: 1. Patient was treated with growth hormone or other medications or interventions intended to promote growth in the time period covered by the analysis