The cell theory consists of:
1. all living organisms are made up of cells
2. cells are the basic structural/organizational unit of all organisms
3. all cells come from pre-existing cells
The second one is the answer
Researchers selected candidate genes by identifying homozygous tracts shared by all three siblings along with the parental phenotype, this type of study is applied for the inheritance of recessive genes. Since the recessive genes can not be expressed in heterozygous genotype, the back tracking of carriers and homozygous recessive individual will help understand its inheritance pattern. The inheritance of dyt2 can be autosomal recessive. It is usually passed on to progeny of two carriers.