Greenland coastal air temperatures linked to Baffin Bay and Greenland Sea ice conditions during autumn through regional blocking patterns

Variations in sea ice freeze onset and regional sea surface temperatures (SST) in Baffin Bay and Greenland Sea are linked to autumn surface air temperatures (SAT) around coastal Greenland through 500 hPa blocking patterns, 1979-2014. We find strong, statistically significant correlations between Baffin Bay freeze onset and SSTs and SATs across the western and southernmost coastal areas, while weaker and fewer significant correlations are found between eastern SATs, SSTs, and freeze periods observed in the neighboring Greenland Sea. Autumn Greenland Blocking Index (GBI) values and the incidence of meridional circulation patterns have increased over the modern sea ice monitoring era. Increased anticyclonic blocking patterns promote poleward transport of warm air from lower latitudes and local warm air advection onshore from ocean-atmosphere sensible heat exchange through ice-free or thin ice-covered seas bordering the coastal stations. Temperature composites by years of extreme late freeze conditions, occurring since 2006 in Baffin Bay, reveal positive monthly SAT departures that often exceed one standard deviation from the 1981-2010 climate norma

Alpha-thalassemia in blacks: genetic and clinical aspects and interactions with the sickle hemoglobin gene

Abstract Recent advances in molecular genetics have permitted detailed study of the human alpha-globin genes and the causes of alpha-thalassemia. In this review, we examine the causes of alpha-thalassemia in the black population and the consequences of the interactions between alpha- thalassemia and structural hemoglobin variants.</jats:p

Alpha-thalassemia in blacks: genetic and clinical aspects and interactions with the sickle hemoglobin gene

Recent advances in molecular genetics have permitted detailed study of the human alpha-globin genes and the causes of alpha-thalassemia. In this review, we examine the causes of alpha-thalassemia in the black population and the consequences of the interactions between alpha- thalassemia and structural hemoglobin variants.</jats:p

Selective enzymatic amplification of alpha 2-globin DNA for detection of the hemoglobin Constant Spring mutation

Abstract Hemoglobin Constant Spring is an elongation mutation of the alpha 2- globin locus that results in a thalassemic phenotype. It has a high prevalence in Asian populations. When inherited with other alpha- thalassemia determinants, the Constant Spring gene has the potential to cause severe forms of alpha-thalassemia. Accurate diagnosis of the condition with standard hemoglobin electrophoresis is unreliable due to the small to undetectable amounts of the mutant hemoglobin present. Because of the extensive sequence homology of the alpha 1 and alpha 2 loci, allele-specific hybridization to total genomic DNA containing the Constant Spring gene would not distinguish between heterozygous and homozygous hemoglobin Constant Spring. Selective enzymatic amplification of alpha 2-globin DNA sequences, however, allows unambiguous diagnoses to be made using allele-specific hybridization. This method is useful for providing accurate genetic counseling and prenatal diagnosis in populations and specific families in which precise diagnosis is important.</jats:p

Asymmetrically primed selective amplification/temperature shift fluorescence polymerase chain reaction to detect the hemoglobin Constant Spring mutation

Hemoglobin (Hb) Constant Spring is an alpha-thalassemic hemoglobinopathy that is a major cause of severe alpha-thalassemia in Southeast Asians. The difficulty of diagnosing Hb Constant Spring using standard electrophoretic methods has led to interest in DNA-dependent diagnostic methods. The methods developed have had to contend with the high degree of homology of the alpha 2-globin gene (the site of the Hb Constant Spring mutation) and the alpha 1-globin gene. We have developed a single reaction polymerase chain reaction-based method that uses asymmetric priming and a temperature shift to accomplish dual ends, selective amplification of alpha 2 but not alpha 1 DNA and discrimination of normal and Hb Constant Spring alpha 2 genes by allele- specific fluorescence polymerase chain reaction. Advantages of this method over previous approaches include avoiding radioisotopes, precluding the need for electrophoresis, and serving as its own control for successful amplification. It is readily applicable to routine diagnosis, population screening, and prenatal diagnosis.</jats:p