Microscopical palynology: Birch woodland expansion and species hybridisation coincide with periods of climate warming during the Holocene epoch in Iceland.

Introgressive hybridisation between arctic dwarf birch (Betula nana) and European downy birch (B. pubescens) is relatively common in natural woodlands in Iceland. As dwarf birch is a diploid species and downy tree birch a tetraploid species, their hybrids are triploid.

Larger head circumference in Icelandic children 0-4 years of age compared to the World Health Organization and Swedish growth charts.

Aim: The World Health Organization (WHO) published universal growth standards for children below five year of age in 2006. Traditionally, Swedish growth references have been used to monitor growth of children in Iceland, but it is not yet known how they compare with these reference charts.

Methods: A total of 2128 longitudinal measurements of length or height, 2132 of weight and 2126 of head circumference between birth and four years of age were collected in 1996-2000 from 199 healthy children (53% boys) recruited at Landspitali University Hospital.

Fourteen sequence variants that associate with multiple sclerosis discovered by meta-analysis informed by genetic correlations.

A meta-analysis of publicly available summary statistics on multiple sclerosis combined with three Nordic multiple sclerosis cohorts (21,079 cases, 371,198 controls) revealed seven sequence variants associating with multiple sclerosis, not reported previously. Using polygenic risk scores based on public summary statistics of variants outside the major histocompatibility complex region we quantified genetic overlap between common autoimmune diseases in Icelanders and identified disease clusters characterized by autoantibody presence/absence. As multiple sclerosis-polygenic risk scores captures the risk of primary biliary cirrhosis and vice versa ( = 1.

Effect of sequence variants on variance in glucose levels predicts type 2 diabetes risk and accounts for heritability.

Sequence variants that affect mean fasting glucose levels do not necessarily affect risk for type 2 diabetes (T2D). We assessed the effects of 36 reported glucose-associated sequence variants on between- and within-subject variance in fasting glucose levels in 69,142 Icelanders. The variant in TCF7L2 that increases fasting glucose levels increases between-subject variance (5.