Genome-wide linkage analyses of non-Hispanic white families identify novel loci for familial late-onset Alzheimer’s disease

INTRODUCTION:

Few high penetrance variants that explain risk in late-onset Alzheimer’s disease (LOAD) families have been found.

METHODS:

We performed genome-wide linkage and identity-by-descent (IBD) analyses on 41 non-Hispanic white families exhibiting likely dominant inheritance of LOAD, and having no mutations at known familial Alzheimer’s disease (AD) loci, and a low burden of APOE ε4 alleles.

Manhattan plot of parametric 2-point affecteds-only results (Red lines represent HLOD = 3.5 for significant linkage and 4.0 for highly significant linkage). Image from PubMed Neurology

RESULTS:

Two-point parametric linkage analysis identified 14 significantly linked regions, including three novel linkage regions for LOAD (5q32, 11q12.2-11q14.1, and 14q13.3), one of which replicates a genome-wide association LOAD locus, the MS4A6A-MS4A4E gene cluster at 11q12.2. Five of the 14 regions (3q25.31, 4q34.1, 8q22.3, 11q12.2-14.1, and 19q13.41) are supported by strong multipoint results (logarithm of odds [LOD*] ≥1.5). Nonparametric multipoint analyses produced an additional significant locus at 14q32.2 (LOD* = 4.18). The 1-LOD confidence interval for this region contains one gene, C14orf177, and the microRNA Mir_320, whereas IBD analyses implicates an additional gene BCL11B, a regulator of brain-derived neurotrophic signaling, a pathway associated with pathogenesis of several neurodegenerative diseases.

DISCUSSION:

Examination of these regions after whole-genome sequencing may identify highly penetrant variants for familial LOAD.

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