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The gamma-aminobutyric acid (GABA)-synthesizing enzyme glutamate decarboxylase (GAD) was studied during development of the chick telencephalon. By means of reverse-phase HPLC analysis, we showed that GABA indeed accumulates during embryogenesis, whereas the levels of glutamate, the substrate for GAD, are more or less unchanged up to later developmental stages. The enzyme activity increased approximately 25-fold from embryonic day 3 to embryonic day 17. Immunoblotting data revealed that two GAD proteins, of approximately 65 and 67 kDa, were present during the period investigated. Furthermore, Northern blot analysis with probes obtained from rat cDNA sequences, as well as a chicken-specific probe for GAD65 generated by means of reverse transcriptase-polymerase chain reaction (RT-PCR), strengthened the interpretation that the chick embryo expresses genes corresponding to GAD65 and GAD67. The rat probes recognized transcript sizes of 3.9 kb (GAD65) and 5.6 kb (GAD67), sizes which are different from those of the rat brain (Erlander et al., Neuron, 7, 91-100, 1991). Sequencing of the RT-PCR products revealed a high level of homology (82% at the nucleotide level) between the mammalian and chick GAD65 genes. Taken together, these findings suggest that the chick embryo expresses two GAD genes during embryogenesis. The functional properties of each gene product remain to be investigated.

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The aim of this study was to investigate allelic imbalance at the major human prostate cancer susceptibility locus HPC1 at 1q24–25 and the recently reported, putative, susceptibility locus at 1p36 in prostate tumors from Swedish families with hereditary prostate cancer. We analyzed 31 prostate tumors and two lymph node metastases from 33 Swedish men in 22 families with hereditary prostate cancer for the presence of allelic imbalance using microsatellite markers D1S158, D1S422, and D1S238 for the HPC1 locus and D1S1597, D1S407, and D1S489 for the 1p36 locus. Frequencies of allelic imbalance at the two investigated loci were quite low, 3 of 27 informative tumors at the 1p36 locus and 3 of 27 informative tumors at the HPC1 locus. Interestingly, two tumors showed allelic imbalance at both loci investigated, suggesting that they may have lost a great part of chromosome 1. Taking this possibility into consideration, the specific loss of the two investigated loci may be even lower (1 of 27 informative tumors for either locus). The very low level of allelic imbalance found at HPC1 and 1p36 makes it unlikely that these loci encode genes that are acting as classic tumor suppressor genes in the initiation or progression of hereditary prostate cancer. Of the eight tumors from HPC1‐linked families, only two showed AI at the HPC1 locus, one of which had lost the wild‐type allele. © 2000 Wiley‐Liss, Inc.

Hereditary prostate cancer is a genetically heterogeneous disease, and so far four different susceptibility loci have been identified. Reports of associated cancers are few, and it is generally considered a site-specific disease. However, some reports have shown an elevated risk for prostate cancer among BRCA2 mutation carriers. In this report, we present a family in which the father and four of his sons were diagnosed with prostate cancer at exceptionally early ages (51, 52, 56, 58, and 63 years, respectively). In addition, three daughters were diagnosed with breast cancer between the ages of 47 and 61. In this family, a truncating mutation in exon 11, 6051delA of the BRCA2 gene, leading to an early termination of the protein (codon 1962), was identified. Although BRCA2 is probably responsible only for a very small fraction of hereditary prostate cancers, this finding supports previous reports of an increased risk of prostate cancer in BRCA2 mutation carriers.