4449
This study examines several biological properties of C5 - deficient ( C5D ) human serum , particularly sera obtained from two C5D homozygotes .
 C5 - deficient, C5D, C5D
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease 
Text: {0} 
Answer:
 C5 - deficient, C5D, C5D