The origin of the major cystic fibrosis mutation (delta F508) in European populations

delta F508 is the most frequent cystic fibrosis (CF) mutation and accounts for approximately 70% of CF chromosomes worldwide. Three highly polymorphic microsatellite markers have been used to study the origin and evolution of delta F508 chromosomes in Europe. Haplotype data demonstrate that delta F508 occurred more than 52,000 years ago, in a population genetically distinct from any present European group, and spread throughout Europe in chronologically distinct expansions, which are responsible for the different frequencies of delta F508 in Europe.

Mutations in the pyruvate kinase L gene in patients with hereditary hemolytic anemia

We have completely sequenced the introns of the human L-type pyruvate kinase (PK) gene using the published cDNA sequence. Subsequently, DNA from 12 unrelated PK deficiency (PKD) patients of Central European origin was investigated for mutations in this gene by solid-phase sequencing. We detected 10 different mutations, 9 of which result in single amino acid alterations, whereas the tenth destroys a splice site. Eight of the 10 mutations have not been described before. We found 7 missense mutations: G994-->A (Gly-332-->Ser), G1006-->T (Ala-336-->Ser), A1081-->G (Asn-361-->Asp), G1174-->A (Ala-392-->Thr), G1493-->A (Arg-498-->His), G1529-->A (Arg-510-->Gln), C1594-->T (Arg-532-->Trp), one in-frame triplet deletion (del) as well as one insertion (ins): del AAG1060-62 (del Lys-354), ins AGC after C1203 (ins Ser after Cys-401), and one splice-site mutation at the border of intron A to exon 3: g/G283-->a/G. Although the enzymatic properties are substantially changed in all PK mutations, only two affected amino acid positions are in or close to the active site. Mutations C1594-->T, G994-->A, del AAG1060-62 and the splice-site mutation g/G283-->a/G have been detected in two different patients each. Mutation G1529-->A was found in five different alleles. Haplotype analysis with the A/C polymorphism at position 1705 gave evidence for a single origin of this most frequent mutation in PKD as suggested by Baronciani and Beutler (Proc Natl Acad Sci USA 90:4324, 1993). Carrier detection and prenatal diagnosis are now feasible for the affected families.

Imprinting mutations suggested by abnormal DNA methylation patterns in familial Angelman and Prader-Willi syndromes

The D15S9 and D15S63 loci in the Prader-Willi/Angelman syndrome region on chromosome 15 are subject to parent-of-origin-specific DNA methylation. We have found two Prader-Willi syndrome families in which the patients carry a maternal methylation imprint on the paternal chromosome. In one of these families, the patients have a small deletion encompassing the gene for the small nuclear ribonucleoprotein polypeptide N, which maps 130 kb telomeric to D15S63. Furthermore, we have identified a pair of nondeletion Angelman syndrome sibs and two isolated Angelman syndrome patients who carry a paternal methylation imprint on the maternal chromosome. These Angelman and Prader-Willi syndrome patients may have a defect in the imprinting process in 15q11-13. We propose a model in which a cis-acting mutation prevents the resetting of the imprinting signal in the germ line and thus disturbs the expression of imprinted genes in this region.

Keratin 9 gene mutations in epidermolytic palmoplantar keratoderma (EPPK)

We have isolated the gene for human type I keratin 9 (KRT9) and localised it to chromosome 17q21. Patients with epidermolytic palmoplantar keratoderma (EPPK), an autosomal dominant skin disease, were investigated. Three KRT9 mutations, N160K, R162Q, and R162W, were identified. All the mutations are in the highly conserved coil 1A of the rod domain, thought to be important for heterodimerisation. R162W was detected in five unrelated families and affects the corresponding residue in the keratin 14 and keratin 10 genes that is also altered in cases of epidermolysis bullosa simplex and generalised epidermolytic hyperkeratosis, respectively. These findings provide further evidence that mutations in keratin genes may cause epidermolysis and hyperkeratosis and that hyperkeratosis of palms and soles may be caused by different mutations in the KRT9 gene.

Association of C4B deficiency (C4B*Q0) with erythema nodosum in leprosy

A considerable number of studies have postulated significant associations between susceptibility to the different clinical manifestations of leprosy and the MHC. In this investigation, the association between the MHC class III complement proteins C2, BF, C4A and C4B and leprosy in a patient population of Southern Brazil was studied. A total of 109 non-related leprosy patients was investigated; 73 presented with lepromatous leprosy (LL), 46 of them had the immunopathological reaction of erythema nodosum (ENL), the remaining 36 were tuberculoid, borderline and indeterminate leprosy (TIBL) patients. The control group included 172 healthy individuals matched with the patients according to their ethnic and geographical origin. C2, BF, C4A and C4B allotypes were determined by standard technologies including Western blots for C2 and C4 variant alleles with monoclonal and polyclonal antibodies. Non-expressed ('silent') C4 alleles in hemizygously deficient individuals were estimated semiquantitatively on the basis of the C4A and C4B isotype ratio and by the MASC ('minimal chi-square') method. The results showed a significantly elevated presence of the non-expressed C4B allele (C4B*Q0) in the LL and ENL patient groups in comparison with the controls. The most significant difference was observed in the ENL group when compared with the controls. In addition, all patients who were homozygously C4B-deficient had ENL, and most of them had the BF*F1 allele. The comparison between LL patients with and without ENL also showed a statistically significant difference in the presence of C4B*Q0, indicating that C4B deficiency itself is associated with ENL. The relative risk of LL patients with the C4B*Q0 allele suffering from ENL was 5.3 compared with LL patients without C4B*Q0. Since immune complexes (IC) are considered to be the pathogenic cause of ENL, our findings indicate that C4B deficiency may play an important role in the abnormal immune response against Mycobacterium leprae and in the lack of IC clearance, leading to ENL reactions. Individuals with this allele seem to be at a higher risk of developing pathological immune reactivity in lepromatous leprosy.

Linkage analysis in German breast cancer families with early onset of the disease, using highly polymorphic markers from the chromosome 17q11-q24 region

Linkage analysis in German breast cancer families with early onset of the disease by using six markers on chromosome 17q11-q24 has been carried out. In the region between markers D17S250 and GH, three markers showed positive LOD scores at an estimated distance of zero. Evidence for linkage is greatest for D17S250, with a LOD score of 2.42.

Environmental trichlorfon and cluster of congenital abnormalities

Of 15 live births in one Hungarian village in 1989-90, 11 (73%) were affected by congenital abnormalities and 6 were twins. Of the 11, 4 had Down syndrome. Likely causes of such clusters (known teratogenic factors, familial inheritance, consanguinity) were excluded. A case-control study and environmental investigations pointed the finger of suspicion at the excessive use of trichlorfon at local fish farms. The content of this chemical was very high in fish (100 mg/kg) and several pregnant women, including all mothers of babies with Down syndrome, had consumed contaminated fish in the critical period for the congenital abnormalities observed.

Missense variations in the cystic fibrosis gene: heteroduplex formation in the F508C mutation

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Ectopic transcription of the parathyroid hormone gene in lymphocytes, lymphoblastoid cells and tumour tissue

Using reverse transcription polymerase chain reaction, steady-state levels of parathyroid hormone (PTH) mRNA were investigated in a number of human, bovine and rat tissues. Transcripts were consistently detected in parathyroid glands as well as in lymphocytes, lymphoblastoid cells and several tumours. Levels of transcription were not measurably increased in lymphoblastoid cells and tumour tissues compared with unstimulated peripheral lymphocytes. The level of 'ectopic' transcription of the PTH gene in lymphoblastoid cells appeared to be resistant to the administration of both vitamin D and phorbol esters.

Mapping of a gene for epidermolytic palmoplantar keratoderma to the region of the acidic keratin gene cluster at 17q12-q21

Epidermolytic palmoplantar keratoderma (EPPK) (Vörner-Unna-Thost) is an autosomal dominantly inherited skin disease of unknown etiology characterized by diffuse severe hyperkeratosis of the palms and soles and, histologically, by cellular degeneration. We have mapped a gene for EPPK to chromosome 17q11-q23, with linkage analysis using microsatellite DNA-polymorphisms, in a single large family of 7 generations. A maximum lod score of z = 6.66 was obtained with the probe D17S579 at a recombination fraction of theta = 0.00. This locus maps to the same region as the type I (acidic) keratin gene cluster. Keratins, members of the intermediate filament family, the major proteins of the cytoskeleton in epidermis, are differentially expressed in a tissue-specific manner. One acidic keratin, keratin 9 (KRT9), is expressed only in the terminally differentiated epidermis of palms and soles. The KRT9 gene has not yet been cloned; however, since the genes for most acidic keratins are clustered, it is highly probable that it too will map to this region. We therefore propose KRT9 as the candidate gene for EPPK.

Band-specific localization of the microsatellite at D13S71 by microdissection and enzymatic amplification

Microsatellite DNA consists of tandemly repeated simple DNA sequence motifs, the number of these repeats being polymorphic. These recently described polymorphisms are ubiquitously distributed throughout the human genome and are highly informative, making them ideal markers for linkage analysis. Physical localization of these microsatellites is an important prerequisite for aligning physical and genetic maps. We have physically mapped the microsatellite at D13S71, which has previously been assigned to chromosome 13. Band-specific mapping of D13S71 to the distal part of band 13q32, near 13q33, was achieved by microdissection of GTG-banded chromosomes and subsequent enzymatic amplification with a heminested PCR approach. Analysis of a panel of somatic cell hybrids confirmed this localization. The technique presented may also be useful in a variety of complex mapping situations and whenever the precise localization of very small (as small as 70 bp) DNA probes is necessary.

Association of major histocompatibility complex class III complement components C2, BF, and C4 with Brazilian paracoccidioidomycosis

A genetic influence of the major histocompatibility complex (MHC) on the susceptibility and the development of the different clinical forms of paracoccidioidomycosis (PCM) has been postulated. In the present investigation allotypes of MHC-coded class III gene products (complement components C2, BF, C4A, and B) were determined in 69 Brazilian PCM patients and 225 healthy control individuals matched for ethnic and geographic origin. The frequency of the non-expressed C4B allele (C4B*Q0) was significantly elevated in comparison to the controls (p less than 0.01; Fisher's exact test). Three out of 69 patients had a complete C4B deficiency as against 2 among 223 control individuals. The C4A*Q0 allele was also more frequent in the patients. Other C4 alleles were not seen to differ between the two groups. The analysis of BF allotypes showed a non-significant predominance of the rarer allele BF*S07 in the patients, whereas no difference in the distribution of C2 alleles was seen. The data on MHC class III association may support the hypothesis of immune response modulation in PCM and suggest a functional genetic role of complement action against the fungus and in the outcome of PCM infection. We conclude that MHC class III products, especially C4B*Q0, are associated with chronic uni- or multifocal PCM and may influence the course of the infection.

Genotype-phenotype correlations in cystic fibrosis patients

Genetic and biomedical data from 346 cystic fibrosis patients of German origin have been evaluated. We demonstrated an age dependent distribution of CFTR genotypes, and confirmed the previously reported association between the dF508 mutation in the CFTR gene and pancreatic insufficiency. However 3 out of 22 pancreatic sufficient patients were dF508 homozygous. When patients were grouped with respect to height development, significant differences were seen in the distribution of J3.11-MspI alleles. We conclude that genetic determinants in and around the CFTR gene contribute to the variability in the clinical course of the disease.

Distribution patterns of the delta F508 mutation in the CFTR gene of CF-linked marker haplotypes in the German population

We have measured the frequency of the delta F508 mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene and its association with cystic fibrosis (CF)-linked marker haplotypes in the German population. Based on the analysis of 400 CF chromosomes, the frequency of the delta F508 mutation is estimated to be 77.3%, the vast majority being associated with marker haplotype KM19-XV2c 2 1. Our data further suggest the presence of another frequent CF mutation associated with this marker haplotype.

Frequency of the delta F508 mutation and flanking marker haplotypes at the CF locus from 167 Czech families

This study analyses distribution patterns of the delta F508 mutation of the cystic fibrosis transmembrane conductance regulator gene (CFTR) gene and the cystic fibrosis (CF)-linked marker loci MET, D7S23, D7S399, and D7S8 in a sample of 167 (116 complete) CF families from Bohemia and Moravia (Czechoslovakia). DNA typing was performed by polymerase chain reaction amplification, restriction analysis, and agarose or polyacrylamide gel electrophoresis. The frequency of the delta F508 mutation in this sample is 67% and the frequency of the B haplotype is 77.6% on CF chromosomes. Linkage disequilibrium was found between delta F508 and all markers tested.

Cloning and sequence analysis of the human parathyroid hormone gene region

A region of 50 kb around the human PTH gene was cloned and mapped by restriction analysis. Sequence analysis was performed and 3270bp determined, completing the sequence of the gene. The nucleotide sequence was analysed with regard to homology between human, bovine and rat PTH genes, and various potential cis-acting regulatory elements were identified. The gene region lacks an obvious CpG island. The PTH gene region in patients suffering from (pseudo)-hypoparathyroidism was investigated by Southern blotting. No detectable alteration in the fragment patterns was observed. Results of segregation analysis in families with affected individuals was inconclusive.

Porencephalic cyst in pycnodysostosis

We describe a case of pycnodysostosis with porencephaly and suggest an explanation for the porencephaly by a mechanism of imbalance between brain growth and its vascular supply and a normal but unopposed cerebrospinal fluid pressure.

Comparison of Dioptron Nova refractive data with conventional refractive data

Refractive data obtained by means of the Dioptron Nova Diagnostic Eye Computer were compared to data obtained by conventional clinical refraction on a group of 236 clinic patients. Spherical equivalent power data were found to average -0.32 D more for Dioptron Nova data than for clinical data, whereas spherical power data averaged -0.25 D more for Dioptron Nova data than for clinical data, and cylinder power averaged -0.12 D more for Dioptron Nova data. Dioptron and clinical data were found to be within +/- 0.50 D of each other for 74% of eyes for spherical equivalent power, for 83% of eyes for spherical power, and for 91% of eyes for cylinder power. Cylinder axis data were found to be within +/- 10 degrees for the two methods for 78% of eyes.

[Effect of air-electric fields on driving and reaction patterns. Test subjects in the car driving simulator (author's transl)]

In the relevant frequency range of about 10 Hertz cars can be considered very largely as Faraday cages and consequently as screens against air-electric fields. This may have a negative influence on driving and reaction patterns as a result. In an extensive investigation 48 subjects in a driving simulator were exposed to definite artificially produced air-electric fields. The self-rating of the performance and concentration of the subjects, reaction times and driving errors were determined. While the reaction times remained practically constant, the driving behavior of the subjects improved.