Prader-Willi Syndrome Body Composition

Lean tissue mass and adipose tissue mass will be determined by dual energy x-ray absorptiometry (DXA) (Hologic Densitometer Discovery A, USA).

Body mass index will be calculated as the body mass in kilograms divided by the square of the height in meters.

A baseline hydraulic dynamometer will be used to assess the grip muscle strength. The upper extremity muscle quality (ratio of muscular strength to muscle mass) will be calculated by dividing handgrip strength by arm lean mass.

The 30-second sit to stand test assesses endurance by counting the number of sit to stand ups achieved.

The timed up and go test measures the time required to rise from a chair, walk a 3-meter-long line on the floor, turn around, walk back, and sit down again.

The two minute step up test measures aerobic endurance by having the subject marching in place for two minutes, lifting alternatively the knees to a midway between patella and iliac crest height of a tape (marked at the wall).

Berg balance scale assesses simple mobility function tasks (sit unsupported, sit-to-stand, stand to sit, stand unsupported, transfer, stand with eyes closed and feet together) and more difficult balance tasks (turn to look behind, retrieve object from floor, turn 360 degrees, reach forward with an outstretched arm, tandem stand, place alternate foot on stool, and single leg stand). It is a 14 item list with each item consisting of a five-point ordinal scale ranging from 0 to 4. A maximum scoring of 56 indicates functional balanced, while scoring< 45 indicates higher risk of falling.

Measurements of serum levels of total cholesterol, triglyceride, low-density lipoprotein, and high-density lipoprotein will be determined using biochemical automatic analyzer according to the manufacturer's recommendations and established methods in the literature.

Measurements of serum levels of fasting glucose will be determined using biochemical automatic analyzer according to the manufacturer's recommendations and established methods in the literature.

Measurements of the glycated hemoglobin (HbA1c) of fasting glucose will be determined using biochemical automatic analyzer according to the manufacturer's recommendations and established methods in the literature.

The appendicular skeletal muscle mass (ASM) will be obtained from the dual energy x-ray absorptiometry (DXA) (Hologic Densitometer Discovery A, USA) measurement, excluding the bone mass from the mass of the extremities, from which fat mass is already excluded. ASM (kg)=lean body mass of extremity - bone mass of extremity.

The lower extremity skeletal muscle mass (LESM) will be obtained from the dual energy x-ray absorptiometry (DXA) (Hologic Densitometer Discovery A, USA) measurement, by excluding the bone mass of the lower extremity, from which fat mass is already excluded. LESM (kg)=lean body mass of lower extremity - bone mass of lower extremity.

Skeletal muscle mass index (SMI) (%) will be calculated using the values measured via the dual energy x-ray absorptiometry (DXA) (Hologic Densitometer Discovery A, USA) as follow= ASM (kg)/body weight (kg)×100 Lower extremity skeletal muscle mass (LESM) (%) will be calculated using the values measured via the dual energy x-ray absorptiometry (DXA) (Hologic Densitometer Discovery A, USA) as follow= LESM (kg)/lower extremity body weight (kg)×100)