Ghosh, S., Hauser, E.R., Magnuson, V.L., Valle, T., Watanabe, R.M., Ally, D., 
Erdos, M.R., Balow, J., Bergman, R.N., Tuomilehto, J., Collins, F.S., and 
Boehnke, M. for the Finland-US Investigation of NIDDM Genetics (FUSION) Study.
A Genome Scan on 709 Finnish Type 2 Diabetes Affected Sib Pairs Reveals
Suggestive Evidence For Linkage On Chromosome 20q. Diabetes, 47:A15, 1998.

The FUSION study is a collaborative effort to map genes for Type 2 diabetes 
in the Finnish population. We have completed an initial genome scan at an 
average resolution of 10cM using 327 marker typed on a total of 709 affected 
sib pairs from 472 families. Our analysis strategy involves semi-parametric
multipoint linkage analysis based on identity by descent. Our best evidence 
for a Type 2 diabetes susceptibility gene is on chromosome 20q, where a 
weighted maximum LOD score (MLS) of 2.47 at 57cM from the pter was detected 
under both an additive model and using the possible triangle method 
(recurrence risk ratio for siblings, lambda s=1.32). Stratification of 
families based on the mean age-of-diagnosis had a MLS of 3.22 at 70cM. 
In addition, 17% of the families with the lowest fasting insulin/fasting 
glucose levels (an index for insulin secretion in affected individuals)
provided the biggest contribution to the total LOD score (MLS=3.22 at 57cM). 
Since the HNF4alpha (MODY 1) gene is estimated to be at 59cM we are now in 
the process of excluding this gene by molecular scanning of the 12 exons, 
the 3' untranslated and promoter regions. Results have so far shown that
no variation in the HNF4alpha gene explains the suggestive linkage in this 
region of chromosome 20.