The epidermal differentiation complex (EDC) comprises a large number of genes that are of crucial importance for the maturation of the human epidermis. So far, 27 genes of 3 related families encoding structural as well as regulatory proteins have been mapped within a 2-Mb region on chromosome 1q21. Here we report on the identification of 10 additional EDC genes by a powerful subtractive hybridization method using entire YACs (950 e 2 and 986 e 10) to screen a gridded human keratinocyte cDNA library. Localization of the detected cDNA clones has been established on a long-range restriction map covering more than 5 Mb of this genomic region. The genes encode cytoskeletal tropomyosin TM30nm (TPM3), HS1-binding protein Hax-1 (HAX1), RNA-specific adenosine deaminase (ADAR1), the 34/67-kD laminin receptor (LAMRL6), and the 26S proteasome subunit p31 (PSMD8L), as well as five hitherto uncharacterized proteins (NICE-1, NICE-2, NICE-3, NICE-4, and NICE-5). The nucleotide sequences and putative ORFs of the EDC genes identified here revealed no homology with any of the established EDC gene families. Whereas database searches revealed that NICE-3, NICE-4, and NICE-5 were expressed in many tissues, no EST or gene-specific sequence was found for NICE-2. Expression of NICE-1 was up-regulated in differentiated keratinocytes, pointing to its relevance for the terminal differentiation of the epidermis. The newly identified EDC genes are likely to provide further insights into epidermal differentiation and they are potential candidates to be involved in skin diseases and carcinogenesis that are associated with this region of chromosome 1. Moreover, the extended integrated map of the EDC, including the polymorphic sequence tag site (STS) markers D1S1664, D1S2346, and D1S305, will serve as a valuable tool for linkage analyses.

The gene encoding the GABAB receptor (GABABR1) maps close to the HLA-F locus on chromosome 6p21.3 in the same region to which a major susceptibility locus for common subtypes of idiopathic generalized epilepsy (IGE), designated as EJM1, has been localized. Moreover, animal models suggest that the GABAB receptor plays a critical role in the epileptogenesis of absence seizures. Accordingly, the present association study tested the candidate gene hypothesis that genetic variants of the human GABABR1 gene confer susceptibility to common subtypes of IGE. Three DNA sequence variants in exons 1a1, 7, and 11 of the GABABR1 gene were assessed by PCR-based restriction fragment length polymorphisms in 248 unrelated probands of German descent, comprising 72 patients with juvenile myoclonic epilepsy (JME), 46 patients with idiopathic absence epilepsy (IAE), and 130 control subjects without a history of epileptic seizures and lack of generalized spike-wave discharges in their electroencephalogram. The results revealed no evidence for an allelic association of any of the GABABR1 sequence variants with either JME or IAE (P > 0.18). Thus, we failed to demonstrate that any of the three exonic GABABR1 variants themselves, or other so-far unidentified mutations, which are in strong linkage disequilibrium with the investigated variants, are involved in the pathogenesis of common IGE subtypes.

The expression control of activating and inhibitory killer cell Ig-like receptors (KIR) on natural killer (NK) cells is highly relevant for the initiation of NK cell mediated cytolysis and cytokine secretion. Transcription start points of nine human KIR genes from two Caucasian donors and the NK cell line NK3.3 were investigated. To overcome sensitivity problems due to the low abundance of the respective transcripts, a novel protocol, specific amplification of cDNA ends (SPACE) with superior specificity and sensitivity was applied. A total of 235 individual SPACE clones resulting from different KIR genes were analysed and revealed a series of transcription start sites tightly clustered between 10 and 60 bp upstream of the start codon. The comparison of the adjacent putative promoter region of the human, chimpanzee and macaque KIR genes revealed a very high conservation for almost all of the KIR family members. An inter-gene and inter-species comparative approach revealed transcription factor binding sites at regions of maximal homology for all primate KIR genes analysed.

SUMMARYNatural killer (NK) cells keep the surface expression of major histocompatibility complex (MHC) class I molecules under surveillance using killer immunoglobulin-like receptors (KIR). Virus-infected or aberrant cells are frequently characterized by a reduced surface expression of MHC class I antigens and may therefore be removed by cytolysis. NK cells are heterogeneous with regard to the expression of KIR genes. The resulting subpopulations show distinguishable speci®cities allowing the recognition of cells lacking varying combinations of MHC class I antigens. The KIR expression pattern in single NK cells has previously been analyzed by Husain and colleagues by cDNA preampli®cation of CD3 À CD56 single cells and subsequent gene-speci®c polymerase chain reaction. We show here that the data of this study contain inconsistencies. These inconsistencies are discussed in the context of KIR mRNA abundance and single-cell cDNA ampli®cation ef®ciency.