Biomedical subjects

Timo Kanninen

Publications and source records attributed to Timo Kanninen.

6 recordsLinked to original sources

PubMed2005

High-throughput pedigree drawing.

Family trees have long been a valuable visual tool for geneticists in identifying clusters of inherited traits and genotypes. As more data are collected, drawing the graphs by hand becomes impractical and, for this reason, we have developed the pedigree software CraneFoot. It can process any family graph with minimal computational cost by making a pedigree transformation that enables the use of a linear node positioning algorithm. The program is designed for automated drawing to printed media and efficient visual classification of genetically interesting families from large data sets. It also incorporates a robust pedigree topology check with detailed error messages.

Algorithms↗

PubMed2004

Meta-analysis of genome-wide scans for hypertension and blood pressure in Caucasians shows evidence of susceptibility regions on chromosomes 2 and 3.

Individual genome-wide scans of blood pressure (BP) and hypertension (HT) have shown inconsistent results. The aim of this study was to investigate whether there was any consistent evidence of linkage across multiple studies with similar ethnicity. We applied the genome-search meta-analysis method (GSMA) to nine published genome-wide scans of BP (n = 5) and HT (n = 4) from Caucasian populations. For each study, the genome was divided into 120 bins and ranked according to the maximum evidence of linkage within each bin. The ranks were summed and averaged across studies and significance levels were estimated, on the basis of a distribution function of summed ranks or permutation tests without (PU) or with (PW) a study sample size weighting factor. Chromosome 3p14.1-q12.3 showed consistent evidence of linkage to HT (PU = 0.0001 and PW = 0.0001), diastolic BP (DBP) (PU = 0.007 and PW = 0.02), HT and DBP pooled (PU = 0.00002 and PW = 0.0001) and HT and systolic BP (SBP) pooled (PU = 0.0003 and PW = 0.0005). Chromosome 2p12-q22.1 showed evidence of linkage to HT (PU = 0.003 and PW = 0.009), DBP (PU = 0.05 and PW = NS), HT and DBP pooled (PU = 0.001 and PW = 0.004) and HT and SBP pooled (PU = 0.001 and P W = 0.005). The summed ranks of the HT analysis correlated significantly with those of the DBP (r = 0.20, P = 0.03) but not with those of the SBP. Both loci showed clustering of significant bins in the analysis of HT and DBP. We conclude that modest or non-significant linkage on chromosomes 3p14.1-q12.3 and 2p12-q22.1 in each individual study translates into genome-wide significant or highly suggestive linkages to HT and DBP in our GSMA analysis.

Blood Pressure↗

PubMed2003

A genome wide scan for early onset primary hypertension in Scandinavians.

With the aim of identifying hypertension susceptibility loci, we performed a genome wide scan in Scandinavian sib-pairs with early onset primary hypertension. To be classified as affected, a diagnosis of primary hypertension at age </=50 years was required. Two hundred and forty three patients with onset of primary hypertension at 40.0+/-7.7 (mean+/-SD) years from 91 families (91 sib-ships with a mean of 2.7 and a range of 2-6 affected members per sib-ship) were genotyped with 362 microsatellite markers with a density of approximately 10 cM. Loci obtaining nominal P</=0.016 (LOD score >/= 1.0) were fine mapped with additional markers. Multipoint non-parametric linkage analysis was performed using GENEHUNTER v 2.0. Using simulations, a nominal P</=0.0002 was determined to be a genome wide significant evidence of linkage. In the 10 cM genome wide scan, nominal P</=0.016 were found on chromosomes 1 at 81 cM (P=0.007), 2 at 115 cM (P=0.006), 3 at 108 cM (P=0.006), 14 at 45 cM (P=0.0002) and at 99 cM (P=0.001), 17 at 42 cM (P=0.015) and 19 at 89 cM (P=0.007). After fine mapping of these loci, one of the chromosome 14 loci just obtained the level of genome wide significance (P=0.0002 at 41 cM) and the chromosome 2 locus reached suggestive evidence of linkage (P=0.002 at 118 cM). Our data suggest a hypertension susceptibility locus on chromosome 14 around 41 cM. The locus on chromosome 2 is also promising as it has been implicated in hypertension and blood pressure regulation in earlier genome scans.

Adult↗

PubMed2003

A meta-analysis of four European genome screens (GIFT Consortium) shows evidence for a novel region on chromosome 17p11.2-q22 linked to type 2 diabetes.

Positional cloning is expected to identify novel susceptibility genes underlying complex traits, but replication of genome-wide linkage scan findings has proven erratic. To improve our ability to detect and prioritize chromosomal regions containing type 2 diabetes susceptibility genes, the GIFT consortium has implemented a meta-analysis of four scans conducted in European samples. These included the Botnia I and Botnia II scans, with respectively 58 and 353 pedigrees from Finland and Sweden, the Warren 2 scan performed in 573 multiplex sibships from the UK, and a scan of 143 families from France. The meta-analysis was implemented using the genome-search analysis method (GSMA), an exploratory data analysis technique which is robust across study designs. The analysis provided evidence for linkage of type 2 diabetes to six regions, with the strongest evidence on chromosome 17p11.2-q22 (P=0.0016), followed by 2p22.1-p13.2 (P=0.027), 1p13.1-q22 (P=0.028), 12q21.1-q24.12 (P=0.029), 6q21-q24.1 (P=0.033) and 16p12.3-q11.2 (P=0.033). Linkage analysis of the pooled raw genotype data generated maximum LOD scores in the same regions as identified by GSMA. Altogether, our results have indicated that GSMA is a valuable tool to identify chromosomal regions of interest and that accumulating evidence for linkage from small peaks detected across several samples may be more important than getting a high peak in a single sample. This meta-analysis has led to identification of a novel region on chromosome 17 linked to type 2 diabetes; this region has not been highlighted in any published scan to date but on the basis of these data justifies further exploration.

Chromosome Mapping↗

PubMed2003

A genome-wide scan in families with maturity-onset diabetes of the young: evidence for further genetic heterogeneity.

Maturity-onset diabetes of the young (MODY) is a heterogeneous single gene disorder characterized by non-insulin-dependent diabetes, an early onset and autosomal dominant inheritance. Mutations in six genes have been shown to cause MODY. Approximately 15-20% of families fitting MODY criteria do not have mutations in any of the known genes. These families provide a rich resource for the identification of new MODY genes. This will potentially enable further dissection of clinical heterogeneity and bring new insights into mechanisms of beta-cell dysfunction. To facilitate the identification of novel MODY loci, we combined the results from three genome-wide scans on a total of 23 families fitting MODY criteria. We used both a strict parametric model of inheritance with heterogeneity and a model-free analysis. We did not identify any single novel locus but provided putative evidence for linkage to chromosomes 6 (nonparametric linkage [NPL]score 2.12 at 71 cM) and 10 (NPL score 1.88 at 169-175 cM), and to chromosomes 3 (heterogeneity LOD [HLOD] score 1.27 at 124 cM) and 5 (HLOD score 1.22 at 175 cM) in 14 more strictly defined families. Our results provide evidence for further heterogeneity in MODY.

Adolescent↗

PubMed2002

Contribution of known and unknown susceptibility genes to early-onset diabetes in scandinavia: evidence for heterogeneity.

In an attempt to identify novel susceptibility genes predisposing to early-onset diabetes (EOD), we performed a genome-wide scan using 433 markers in 222 individuals (119 with diabetes) from 29 Scandinavian families with > or =2 members with onset of diabetes < or =45 years. The highest nonparametric linkage (NPL) score, 2.7 (P < 0.01), was observed on chromosome 1p (D1S473/D1S438). Six other regions on chromosomes 3p, 7q, 11q, 18q, 20q, and 21q showed a nominal P value <0.05. Of the EOD subjects in these 29 families, 20% were GAD antibody positive and 68% displayed type 1 diabetes HLA risk alleles (DQB*02 or 0302). Mutations in maturity-onset diabetes of the young (MODY) 1-5 genes and the A3243G mitochondrial DNA mutation were detected by single-strand conformation polymorphism and direct sequencing. To increase homogeneity, we analyzed a subsample of five families with autosomal dominant inheritance of EOD (greater than or equal to two members with age at diagnosis < or =35 years). The highest NPL scores were found on chromosome 1p (D1S438-D1S1665; NPL 3.0; P < 0.01) and 16q (D16S419; NPL 2.9; P < 0.01). After exclusion of three families with MODY1, MODY3, and mitochondrial mutations, the highest NPL scores were observed on chromosomes 1p (D1S438; NPL 2.6; P < 0.01), 3p (D3S1620; NPL 2.2; P < 0.03), 5q (D5S1465; NPL 2.1; P < 0.03), 7q (D7S820; NPL 2.0; P < 0.03), 18q (D18S535; NPL 1.9; P < 0.04), 20q (D20S195; NPL 2.5; P < 0.02), and 21q (D21S1446; NPL 2.2; P < 0.03). We conclude that considerable heterogeneity exists in Scandinavian subjects with EOD; 24% had MODY or maternally inherited diabetes and deafness, and approximately 60% were GAD antibody positive or had type 1 diabetes-associated HLA genotypes. Our data also point at putative chromosomal regions, which could harbor novel genes that contribute to EOD.

Adult↗