Mutations in LMNA cause a severe and progressive DCM in a relevant proportion of patients. Mutation screening should be considered in patients with DCM, in particular when clinical predictors of LMNA mutation are present, regardless of family history.

The need to develop a blood substitute is now urgent because of the increasing concern over blood-transmitted viral and bacterial pathogens. Cell-free haemoglobin solutions and human haemoglobin synthesized in Escherichia coli and Saccharomyces cerevisiae have been investigated as potential oxygen-carrying substitutes for red blood cells. But these haemoglobins cannot be used as a blood substitute because (1) the oxygen affinity in the absence of 2,3-bisphosphoglycerate is too high to allow unloading of enough oxygen in the tissues, and (2) they dissociate into alpha beta dimers that are cleared rapidly by renal filtration, which can result in long-term kidney damage. We have produced a human haemoglobin using an expression vector containing one gene encoding a mutant beta-globin with decreased oxygen affinity and one duplicated, tandemly fused alpha-globin gene. Fusion of the two alpha-globin subunits increases the half-life of this haemoglobin molecule in vivo by preventing its dissociation into alpha beta dimers and therefore also eliminates renal toxicity.

Synthetic genes encoding the human alpha- and beta-globin polypeptides have been expressed from a single operon in Escherichia coli. The alpha- and beta-globin polypeptides associate into soluble tetramers, incorporate heme, and accumulate to greater than 5% of the total cellular protein. Purified recombinant hemoglobin has the correct stoichiometry of alpha- and beta-globin chains and contains a full complement of heme. Each globin chain also contains an additional methionine as an extension to the amino terminus. The recombinant hemoglobin has a C4 reversed-phase HPLC profile essentially identical to that of human hemoglobin A0 and comigrates with hemoglobin A0 on SDS/PAGE. The visible spectrum and oxygen affinity are similar to that of native human hemoglobin A0. The recombinant protein shows a reduction in Bohr and phosphate effects, which may be attributed to the presence of methionine at the amino termini of the alpha and beta chains. We have also expressed the alpha- and beta-globin genes separately and found that the expression of the alpha-globin gene alone results in a marked decrease in the accumulation of alpha-globin in the cell. Separate expression of the beta-globin gene results in high levels of insoluble beta-globin. These observations suggest that the presence of alpha- and beta-globin in the same cell stabilizes alpha-globin and aids the correct folding of beta-globin. This system provides a simple method for expressing large quantities of recombinant hemoglobin and allows facile manipulation of the genes encoding hemoglobin to produce functionally altered forms of this protein.

Generalized vitiligo is a common autoimmune disorder in which patchy loss of skin and hair pigmentation results from loss of pigment-forming melanocytes from the involved regions. Vitiligo occurs with a frequency of about 1% in most populations, and is highly associated with other autoimmune disorders, particularly Hashimoto thyroiditis. Most cases of vitiligo are sporadic, although some cases cluster in families, and the disorder is thought to be oligogenic in origin. We have studied a large family cluster in which vitiligo and Hashimoto thyroiditis occur in numerous individuals. A whole-genome scan of 24 family members, including 14 affected with autoimmune disease, showed significant linkage of an oligogenic autoimmune susceptibility locus, termed AIS1, to a 14.4 cM interval in 1p31.3-p32.2. A two-locus analysis of Hashimoto thyroiditis in family members segregating an AIS1 susceptibility allele showed suggestive linkage to markers in chromosome 6p22.3-q14.1, in a region spanning both the major histocompatibility complex and AITD1, a susceptibility locus for autoimmune thyroid disease. Our results indicate that the 1p AIS1 locus is associated with susceptibility to autoimmunity, particularly vitiligo, in this family, and that a chromosome 6 locus, most likely AITD1, may mediate the occurrence of Hashimoto's thyroiditis in AIS1-susceptible family members.