Table 1.

The Nonreference Siblings were Counted and Classified as Asymptomatic or Symptomatic and Concordant or Nonconcordant—The Latter with Respect to the Reference Sibling (the Oldest Mutation Carrier). The Expected Values were Calculated Assuming Random Inheritance of Chromosome 19q—in which Case, there would be Equal Numbers of Concordant and Nonconcordant for both Asymptomatic and Symptomatic Individuals

	Concordance of genotype with that of reference sibling
	Observed concordance		Expected concordance
	Concordant	Nonconcordant	Concordant	Nonconcordant
Symptomatic	2	16	9	9
Asymptomatic	14	0	7	7