Genetic analysis of a kindred with @entity20136 . Evidence for two separate gene defects: one associated with an abnormal XXXX species, @entity755 -37; and a second associated with low plasma concentrations of @entity755 .

@entity20136 @entity70996 @entity165 @entity755
In 1979 Steinberg and colleagues recognized a unique kindred with @entity70996 (1979. J. Clin. Invest. 64:292-301). We have undertaken an intensive reexamination of this kindred and have studied 41 family members in three generations. In this family we document the presence of two distinct apo B alleles associated with low plasma concentrations of apolipoprotein (apo) B and low density lipoprotein (LDL) @entity165 and we trace the inheritance of these two alleles over three generations. One of the alleles resulted in the production of an abnormal, truncated apo B species, apo B-37. The other apo B allele was associated with reduced plasma concentrations of the normal apo B species, @entity755 . H.J.B., the proband, and two of his siblings had both abnormal apo B alleles and were therefore compound heterozygotes for @entity20136 . Their average LDL- @entity165 level was 6 +/- 9 mg/dl. All of the offspring of the three compound heterozygotes had @entity20136 , and each had evidence of only one of the abnormal apo B alleles. In the entire kindred, we identified six heterozygotes for @entity20136 who had only the abnormal apo B-37 allele and their average LDL @entity165 was 31 +/- 12 mg/dl. We identified 10 heterozygotes who had only the allele for reduced plasma concentrations of @entity755 and their LDL @entity165 level was 31 +/- 15 mg/dl. Unaffected family members (n = 22) had LDL @entity165 levels of 110 +/- 27 mg/dl. This report describes the first kindred in which two distinct abnormal apo B alleles have been identified, both of which are associated with @entity20136 .
