Simplify the following text for a Grade 14 native English-speaking person.
Original: There are many diseases and conditions which cause a decrease in muscle mass , known as atrophy , including : Dejerine Sottas syndrome ( HSMN Type III ) , inactivity , as seen when a cast is put on a limb , or upon extended bedrest ( which can occur during a prolonged illness ) ; cachexia - which is a `` body-wasting '' syndrome that is a co-morbidity of cancer and Congestive Heart Failure ; Chronic Obstructive Pulmonary Disease ; burns , liver failure , etc. .
Simplified: It also develops in several common diseases , including cancer , AIDS , congestive heart failure , Chronic obstructive pulmonary disease , renal failure . It may be observed in Dejerine Sottas syndrome , inactivity , as seen when a cast is put on a limb , or upon extended bed rest ( which can occur during a prolonged illness or hostel research ) ; cachexia , burns , liver failure and starvation .