Manfred Schloesser

Omission of exon 12 in cystic fibrosis transmembrane conductance regulator (CFTR) gene transcripts

SummaryCystic fibrosis transmembrane conductance regulator (CFTR) mRNA transcripts isolated from both expressing and “non-expressing” cell types of normal individuals exhibit differntial splicing to a variable extent in a region encoding the putative nucleotide binding fold of the CFTR polypeptide. Sequence analysis of the aberrant fragments obtained after cDNA polymerase chain reaction amplification confirmed the in-frame joining of exons 11 and 13. The proportion of alternative splicing is reproducible and constant in a given individual. The omission of exon 12 in a significant proportion of transcripts supports the hypothesis that a minimal amount of correctly expressed CFTR is sufficient for the maintenance of a clinically normal phenotype.

A cystic fibrosis patient homozygous for the nonsense mutation R553X.

A cystic fibrosis patient homozygous for the nonsense mutation R553X was identified by mutation screening and the genotype confirmed by DNA sequencing. This patient, the only one described to date who is homozygous for this stop codon in exon 11 of the CFTR gene, is moderately severely affected. Clinical and molecular findings are presented.

A novel 5'-upstream mutation in the factor XII gene is associated with a TaqI restriction site in an Alu repeat in factor XII-deficient patients.

The factor XII gene from factor XII-deficient patients was screened for mutations at the genomic level. In patients negative for cross-reacting material, a T to C transition 224 by upstream of exon 3 was identified (exon 3–224 (T→C)) that creates an additionalTaqI restriction site in intron B. This mutation is located within a putative hormone responsive element and within a B box promoter of an Alu repeat of the Sb0 family. TheTaqI site is associated with a G to C transversion upstream of the transcription initiation site (exon 1–8 (G→C)). We discuss the possible roles of these elements in factor XII gene regulation.

Detection of human spermatid-specific transcripts in peripheral blood lymphocytes of males and females

SummaryWe describe the detection of ectopic (“illegitimate”) transcripts of the proacrosin and protamine 2 genes, which are specific for human spermatogenesis, in non-cultured peripheral blood lymphocytes. After specifically-primed reverse transcription of total lymphocyte RNA, these rare transcripts can be directly visualised after two rounds of polymerase chain reaction with nested primers. Sequence and restriction analyses of the corresponding fragments have confirmed that transcripts of proacrosin and protamine 2 are present in the lymphocytes not only of males, but also of adult females.

A cystic fibrosis patient with the nonsense mutation G542X and the splice site mutation 1717-1.

A cystic fibrosis patient with the genotype G542X/1717-1 (G----A) was identified by DNA sequencing of exon 11 of the CFTR gene. The available molecular and clinical data are presented. This is the first report of a patient with this rare genotype and may serve to improve our understanding of allele interactions.

Homozygous factor V Leiden mutation in a woman with multiple adverse pregnancy outcomes

Abstract We report a case with one intrauterine fetal death (IUFD) at 32 weeks of gestation, one premature delivery at the same week, and one abortion of unknown etiology at 12 weeks of gestation. We discuss that the presence of homozygosity for Factor V Leiden may be associated with placental insufficiency in this woman. Application of anticoagulant therapy may have been beneficial in her current pregnancy.

Two cystic fibrosis patients with the genotype G542X/G551D

Two adult sisters affected by cystic fibrosis were both shown to carry two different alterations within exon 11 of the CFTR gene, the nonsense mutation G542X and the missense mutation G551D. Both patients exhibit a relatively benign clinical course. In the described patients, G542X functions as a “mild” allele and is, in this respect, dominant to the “severe” G551D.