In 75 gliomas and 31 meningiomas, mutations at the epidermal growth factor receptor (EGFR) gene locus were restricted to gliomas. The ligands of this receptor, epidermal growth factor and transforming growth factor alpha, lacked quantitative changes at their loci in gliomas and meningiomas. EGFR gene amplification occurred in astrocytomas, oligodendrogliomas, ependymomas and glioblastomas. The frequency of this mutation significantly increased with the malignancy grade and the patient's age. Especially in glioblastomas of individuals aged over 64 years, EGFR gene mutations were observed without chromosome-10-specific allele losses. This finding contradicts the hypothesis that deletion of one entire chromosome 10 regularly precedes EGFR gene amplification in primary glioblastomas of patients aged over 50 years. It was found that most individuals whose gliomas carry an EGFR gene mutation have a poor prognosis, comparable to that of glioblastoma patients even when the tumour is graded as benign.

Cytogenetic studies were performed on 136 couples with a history of two or more abortions referred to us after gynaecological causes of the abortions had been excluded. Fifteen (11%) of the couples were found to have a chromosome anomaly, and when the couples were subdivided according to number of abortions, surprisingly 6 (10%) of the 59 couples with a history of only two abortions had a chromosome anomaly. An increased frequency of mosaicism for X-chromosome aneuploidy (2.2%) in the women from the 136 couples was also found. A review of the literature shows that translocations of some chromosomes (e.g. nos. 1, 7 or 22) preferentially lead to fetal wastage, while those involving, for example, chromosome nos. 5, 9, 14 or 21 are more likely to result in the birth of a handicapped child. Couples with a history of two abortions should be investigated cytogenetically. Other causes of miscarriages must, however, be excluded first.

In various primary brain tumours of neuroepithelial tissue recombinant DNA techniques were used to demonstrate changes of the epidermal growth factor receptor gene, which is homologous to the c-erbB oncogene. Twenty-one of 40 grade III/IV tumours, but only 1 of 16 grade I/II tumours were found to contain amplified and/or rearranged c-erbB sequences. This highly significant difference suggest that c-erbB amplification, rearrangement, or both, are important steps in malignant transformation in a subset of patients with neuroepithelial tumours.

The occurrence of rare hypervariable Ha-ras alleles or of a rare c-mos allele in white blood cell DNA is claimed to be associated with susceptibility to cancer. We analyzed a group of patients with intracranial tumors to determine whether the occurrence of rare alleles at the Ha-ras locus and at the c-mos locus was increased in comparison with normal individuals. We found a higher incidence of rare hypervariable Ha-ras alleles (9.5% to 3%) and a 5 kilobase EcoRI c-mos allele (2.5% to 0%) in the patients. These results are consistent with the opinion that such unusual alleles are associated with a predisposition to intracranial tumors.

The genomic DNA organisation patterns of four sauropsidian species, namely Python reticularis, Caiman crocodilus, Terrapene carolina triungius and Columba livia domestica were investigated by reassociation of short and long DNA fragments, by hyperchromicity measurements of reannealed fragments and by length estimations of S1-nuclease resistant repetitive duplexes. While the genomic DNA of the three reptilian species shows a short period interspersion pattern, the genome of the avian species is organised in a long period interspersion pattern apparently typical for birds. These findings are discussed in view of the close phylogenetic relationships of birds and reptiles, and also with regard to a possible relationship between the extent of sequence interspersion and genome size.