Hypoglycemia in Prader-Willi Syndrome

This study will include outpatient admission to the clinical research center for IV
placement, blood draws from the IV, poking the participants finger to obtain small amounts
of blood and monitored 6 hour fast. A fast is when a person goes without food for a certain
period of time. The participant will not be fasted longer than 6 hours.

The participant will arrive to the outpatient clinical research center at approximately 7am.
A parent will be expected to stay with the participant at all times. The participant's
finger will be poked for blood (requires approximately one drop of blood) soon after arrival
to make sure his blood sugar is not already low. If the participant's blood sugar is low on
arrival to the Clinical Research Center, additional blood will be drawn through his vein (a
little more than half a teaspoon) and he will not have to complete the rest of the study.
If his blood glucose is above 60 mg/dl, the participant will be given an opportunity to eat
prior to starting the fast. A small tube will be placed in the participant's vein at the
beginning of the fast to make additional blood draws easier. 1/10th a teaspoon of blood
will be sent for cortisol testing when the IV is placed. Cortisol is a hormone that is
important for control of blood sugar. In addition, the participant's finger will be pricked
every hour for blood to monitor his blood sugar by bedside meter. Each finger prick will
require approximately one to two drops of blood. A test to look at fat breakdown (ketones)
will sometimes be checked using the same blood obtained when pricking the finger to check
blood sugar. If a blood sugar of less than 70 mg/dl is found, blood sugars will be checked
by finger prick every 30 minutes instead of every hour. If finger prick blood glucose is
less than 65 mg/dl, blood will be collected and sent to the clinical research center lab to
make sure that the true blood sugar reading is not lower than what is seen on the bedside
meter (requires approximately 1/10 teaspoon of blood). If a blood sugar of less than 60
mg/dl is found, the fast will end and blood will be collected through the IV line (small
tube placed through the vein). The participant will be monitored by a nurse during the
fast. She will check his blood pressure, pulse and respiratory rate periodically to make
sure he is comfortable. After final blood collection, the participant will be allowed to
feed normally and his IV will be removed. During the entire study, we expect to collect at
least ¾ of a teaspoon of blood from the participant. No more than 1.2 teaspoons of blood
will be collected from the participant during this entire study.

If a blood sugar less than 60 mg/dl is found at any time, blood will be drawn from a vein in
the participant's arm and the study will end. He will then be allowed to eat. If he has a
low blood sugar and is unable to feed the way he normally does, sugar water/gel may be given
by mouth or sugar water may be given by the tube placed in his vein. If the participant
normally is fed by a tube placed in his stomach, sugar water may be given through this tube.

Inclusion Criteria:

- Diagnosed with Prader-Willi Syndrome

- Between ages 2-12 months of age

- Determined to be in nutritional phase 1a by clinical assessment

Exclusion Criteria:

- Treatment with growth hormone