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Metabolic coherence (MC) is a network-based approach to dimensionality reduction that can be used, for example, to interpret the joint expression of genes linked to human metabolism. Computationally, the derivation of 'transcriptomic' MC involves mapping of an individual gene expression profile onto a gene-centric network derived beforehand from a metabolic network (currently Recon2), followed by the determination of the connectivity of a particular, profile-specific subnetwork. The biological significance of MC has been exemplified previously in the context of human inflammatory bowel disease, among others, but the genetic architecture of this quantitative cellular trait is still unclear. Therefore, we performed a genome-wide association study (GWAS) of MC in the 1000 Genomes/ GEUVADIS data (n = 457) and identified a solitary genome-wide significant association with single nucleotide polymorphisms (SNPs) in the intronic region of the cadherin 18 (CDH18) gene on chromosome 5 (lead SNP: rs11744487, p = 1.2 × 10 - 8 ). Cadherin 18 is a transmembrane protein involved in human neural development and cell-to-cell signaling. Notably, genetic variation at the CDH18 locus has been associated with metabolic syndrome-related traits before. Replication of our genome-wide significant GWAS result was successful in another population study from the Netherlands (BIOS, n = 2661; lead SNP), but failed in two additional studies (KORA, Germany, n = 711; GENOA, USA, n = 411). Besides sample size issues, we surmise that these discrepant findings may be attributable to technical differences. While 1000 Genomes/GEUVADIS and BIOS gene expression profiles were generated by RNA sequencing, the KORA and GENOA data were microarray-based. In addition to providing first evidence for a link between regional genetic variation and a metabolism-related characteristic of human transcriptomes, our findings highlight the benefit of adopting a systems biology-oriented approach to molecular data analysis.

A new PIQ0 variant (PIQ0riedenburg) is described; it is caused by a complete deletion of the alpha 1-antitrypsin (alpha 1 AT) gene. The deletion gives rise to four new restriction fragment length polymorphisms (RFLPs) detected with a genomic probe of the 5' region of the gene. Analysis of the RFLPs indicates that the deletion starts immediately upstream of exon Ic. The deletion extends into the 3' flanking region of the gene but does not include the alpha 1 AT-related gene (the PIL gene), which is located 12 kb downstream of the alpha 1 AT gene.

By sequence analysis of the complete protein-coding region of the human alpha-1-antitrypsin gene using polymerase chain reaction techniques, we have characterised one of the normal variants, M3. We have identified a single point mutation between M1 Val213 and M3 at codon position 376 which is a GAA(Glu) to GAC(Asp) transversion.

The human serum transferrin (Tf) system was analyzed by isoelectric focusing (IEF) with immobilized pH gradients. For the demonstration of the genetic variability the Fe1-Tf region was chosen. The pH range suitable for analysis of the Tf system was pH 5.20 to pH 5.75. The phenotypes of the common six TfC subtypes are described. No further heterogeneity among TfC1, TfC2, and TfC3 was noted. Aslo presented are the phenotypes of the TfC6 subtype, and of three different TfB and three different TfD variants. IEF with immobilized pH gradients appears to be a suitable method for the analysis of the inherited transferrin polymorphism.

Polyacrylamide gel isoelectric focusing (PAGIF) with carrier ampholytes was used for the determination of Tf phenotypes in a sample of 965 unrelated healthy blood donors from Tuscany (Italy). Thirteen rare variants in a heterozygote state were found (four Tf D, seven Tf B, and two rare Tf C subtypes). Among them two apparently new variants, tentatively called Tf C15 and Tf B4, were identified. The rare Tf B0 mutant was also observed.

The phenotypes of the protease inhibitor (PI) alpha-1-antitrypsin have been analyzed by isoelectric focusing on polyacrylamide gels. With improved resolution by a modified procedure it was possible to demonstrate a fifth PI*M suballele. The bands of PI M5 are located between PI M1 and PI M3. In addition, a further deficiency allele similar to PI*Z was found in a female patient with obstructive pulmonary disease. This variant was provisionally named PI Z augsburg (PI Z aug). Family data confirm a simple codominant mode of inheritance for PI Z aug.

The detection of PI Scologne, a rare variant in the alpha-1-antitrypsin system, by means of isoelectric focusing is described.

The genetic types of the properdin factor B were analyzed by isoelectric focusing on polyacrylamide gels and subsequent immunofixation. Sera from 516 unrelated, healthy individuals from Southern Germany were examined. Two new subtypes of the Bf*S allele were observed. They were provisionally named Bf*Sb1 and Bf*Sb2(b = basic), since the position of their bands is located slightly towards the cathode. Whereas Bf Sb2 has, thus far, been found only in a single individual, Bf Sb1 was found in five unrelated persons and in a mother and her child indicating a simple codominant mode of inheritance. The combined frequency of the Bf*Sb alleles was calculated to be 0.0067.

Isoelectric focusing (IEF) with carrier ampholytes was used for the determination of transferrin C subtypes and transferrin B and D variants in a sample of 1125 unrelated individuals from Southern Germany. The observed TfC allele frequencies were Tf*C1 = 0.7872, Tf*C2 = 0.1365, and Tf*C3 = 0.0675. The rare C subtype C6 was observed twice. A new C subtype, called C10, was observed and identified by IEF with immobilized pH gradients. The rare C subtypes C4 and C8 were also studied by this method. TfB and TfD variants were found with a heterozygous frequency of 1.53%. One new TfD was found which is located between D1 and D2 and therefore named D1-2. Evidence for a Tf null allele was obtained in a child and the putative father; they were considered to be heterozygous for an allele Tf0. The theoretical exclusion rate for paternity examinations was calculated for the Tf system and found to be 17.95%.

Using "new" techniques (malic acid thin layer agarose gel electrophoresis and/or isoelectric focusing), the polymorphism of the human red cell isozyme system esterase D (ESD) was shown to be extended. We report the gene frequencies observed among 312 unrelated Caucasian individuals living in the Düsseldorf area. The finding of a "new" allele at the ESD locus is also described.

We describe a new rare allele for esterase D (EsD) occurring in a Portuguese family with retinoblastoma in two generations.

Phenotypes of orosomucoid (ORM) in human sera have been analysed by isoelectric focusing and print immunofixation. After neuraminidase treatment the band patterns indicated that the polymorphism of the structural locus ORM1 is controlled by three autosomal codominant alleles. According to the previous nomenclature they were called ORM1F1, ORM1F2, and ORM1S. In a study of 272 unrelated individuals from southern Germany, five of the six expected common ORM1 subtypes were observed. Furthermore, we found three ORM variant phenotypes which have not been reported previously. These variants were characterized by additional bands in a cathodal position. One variant had additional double bands and presumably represents a rare ORM1 variant named ORM1S1. Two variants had additional single bands. They were assigned tentatively to the ORM2 gene locus. While the common gene product of ORM2 may be called ORM2A, the two variants are named ORM2B1 and ORM2B2, respectively. ORM2B1 has, thus far, been found only in a single individual; the variants ORM1S1 and ORM2B2 were found in a father-child pair and a mother-child pair, respectively. The frequency for variants tentatively assigned to the ORM2 locus is very low and was calculated to be 0.0037.