The major lung cancer-derived mutants of ERBB2 are oncogenic and are associated with sensitivity to the irreversible EGFR/ERBB2 inhibitor HKI-272.

Mutations in the ERBB2 gene were recently found in approximately 2% of primary non-small cell lung cancer (NSCLC) specimens; however, little is known about the functional consequences and the relevance to responsiveness to targeted drugs for most of these mutations. Here, we show that the major lung cancer-derived ERBB2 mutants, including the most frequent mutation, A775insYVMA, lead to oncogenic transformation in a cellular assay. Murine cells transformed with these mutants were relatively resistant to the reversible epidermal growth factor receptor (EGFR) inhibitor erlotinib, resembling the resistant phenotype found in cells carrying the homologous mutations in exon 20 of EGFR. However, the same cells were highly sensitive to the irreversible dual-specificity EGFR/ERBB2 kinase inhibitor HKI-272, as were those overexpressing wild-type ERBB2. Finally, the NSCLC cell line, Calu-3, overexpressing wild-type ERBB2 owing to a high-level amplification of the ERBB2 gene were highly sensitive to HKI-272. These results provide a rationale for treatment of patients with ERBB2-mutant or ERBB2-amplified lung tumors with HKI-272.

Large scale association analysis for identification of genes underlying premature coronary heart disease: cumulative perspective from analysis of 111 candidate genes.

BACKGROUND: to date, only three groups have reported data from large scale genetic association studies of coronary heart disease using a case control design. METHODS AND RESULTS: to extend our initial report of 62 genes, we present data for 210 polymorphisms in 111 candidate genes genotyped in 352 white subjects with familial, premature coronary heart disease (onset age for men, 45; for women, 50) and a random sample of 418 population based whites. Multivariate logistic regression analysis was used to compare the distributions of genotypes between cases and the comparison group while controlling for age, sex, body mass, diabetes, and hypertension. Significant associations were found with polymorphisms in thrombospondin-4 (THBS4), thrombospondin-2 (THBS2) and plasminogen activator inhibitor-2 (PAI2), the strongest being with the A387P variant in THBS4 (p = 0.002). The THBS2 and THBS4 associations have since been replicated. We evaluated polymorphisms in 40 genes previously associated with coronary heart disease and found significant (p<0.05) associations with 10: ACE, APOE, F7, FGB, GP1BA, IL1RN, LRP1, MTHFR, SELP, and THPO. For five of these genes, the polymorphism associated in our study was different from that previously reported, suggesting linkage disequilibrium as an explanation for failure to replicate associations consistently across studies. We found strong linkage disequilibrium between polymorphisms within and between genes, especially on chromosome 1q22-q25, a region containing several candidate genes. CONCLUSIONS: despite known caveats of genetic association studies, they can be an effective means of hypothesis generation and complement classic linkage studies for understanding the genetic basis of coronary heart disease.

Characterization of two novel protocadherins (PCDH8 and PCDH9) localized on human chromosome 13 and mouse chromosome 14.

The protocadherins are a subfamily of the calcium-dependent cell-cell adhesion and recognition proteins of the cadherin superfamily. In this study we describe the isolation and characterization of two novel protocadherins, PCDH8 and PCDH9, that constitute a new linkage group on human chromosome 13 and mouse chromosome 14. Like other protocadherins both genes are predominantly expressed in brain, but PCDH9 is also expressed in a broader variety of tissues, and the expression patterns appear to be developmentally regulated. We have determined the genomic organization of PCDH8, which differs significantly from that of the other cadherin subfamilies. In contrast to the classical and desmosomal cadherins, which in general consist of 15-17 exons and share a remarkable degree of conservation in intron position, PCDH8 consists of only three exons and lacks introns in the extracellular domain. The first exon encodes the extracellular domain, the transmembrane region, and part of the cytoplasmic tail. The second exon encodes the remainder of the cytoplasmic region and is partially untranslated. The differences in the genomic structure of cadherin subfamilies will be discussed in the context of the evolution of the cadherin superfamily.

Structure and organization of GABRB3 and GABRA5.

The genes encoding the gamma-aminobutyric acid (GABA) type-A receptor subunits beta 3 (GABRB3), alpha 5 (GABRA5), and gamma 3 (GABRG3) map to chromosome 15q11-q13. The three genes are contained within roughly 800 kb of the distal part of the imprinted Prader-Willi and Angelman syndrome region. A 570-kb contig encompassing GABRB3 and GABRA5 has been constructed in P1, lambda phage, and PAC clones. GABRB3 spans 250 kb of DNA and is organized into 9 exons that range from 68 to 504 bp, while GABRA5 is encoded by 11 exons (65 to 924 bp in length) within 86 kb. The exon/intron borders for both genes have been characterized and, primers have been designed to amplify each of the individual exons. Two reference STR markers have been positioned in the contig. The reference STR for GABRB3 is in fact located at least 60 kb beyond the 3' terminus of GABRB3, while D15S97 is contained within intron 4 of GABRB3. The detailed physical map of this GABAA receptor subunit gene cluster should not only be useful in genetic studies of the 15q11-q13 region, but will also be important for investigating the evolution and expression of the GABAA receptor gene superfamily.

Identification of a putative DNA replication origin in the gamma-aminobutyric acid receptor subunit beta3 and alpha5 gene cluster on human chromosome 15q11-q13, a region associated with parental imprinting and allele-specific replication timing.

The region containing the GABAA receptor beta3 and alpha5 subunit-encoding genes is subject to parental imprinting and is organized in different allele-specific replication timing domains. A 60-kb domain displaying a maternal early/paternal late pattern of allele-specific replication timing asynchrony is nested within a larger region displaying the opposite pattern. The proximal portion of this maternal early replicating domain is incorporated into phage clone lambda84. In order to identify DNA structures which may be associated with the boundary between the replication domains, phage lambda84 has been subcloned into smaller fragments and several of these have been analyzed by nucleotide sequencing. A plot of helical stability for 13kb of contiguous sequence reveals several A + T-rich regions which display potential DNA unwinding. The plasmid subclones from phage lambda84 have been analyzed for bent DNA and one of these, p82, contains bent DNA and overlaps with the region of highest potential helical instability. Of the seven plasmids tested, only p82 shows strong autonomous replication activity in an in vitro replication assay, with replication initiating within the genomic insert. These results suggest that a putative origin of DNA replication contained within p82 may play a role in establishing the allele-specific replication timing domains in the GABAA receptor subunit gene cluster.

The gamma-aminobutyric acid receptor gamma 3 subunit gene (GABRG3) is tightly linked to the alpha 5 subunit gene (GABRA5) on human chromosome 15q11-q13 and is transcribed in the same orientation.

GABAA receptors are heterooligomeric ligand-gated ion channels that mediate the effect of the inhibitory neurotransmitter gamma-aminobutyric acid. The GABAA receptors consist of at least 15 different receptor subunits that can be classified into 5 subfamilies (alpha, beta, gamma, delta, rho) on the basis of sequence similarity. Chromosomal mapping studies have revealed that several of the GABAA receptor subunit genes appear to be organized as clusters. One such cluster, which consists of the GABAA receptor beta 3 (GABRB3) and alpha 5 (GABRA5) subunit genes, is located in chromosome 15q11-q13. It is shown here that the GABAA receptor gamma 3 subunit gene (GABRG3) also maps to this region. Lambda and P1 phage clones surrounding both ends of GABRG3 were isolated; the clones derived from the 5' end of GABRG3 were linked to an existing phage contig spanning the 3' end of GABRA5. The two genes are located within 35 kb of each other and are transcribed in the same orientation.

The human gamma-aminobutyric acid receptor subunit beta 3 and alpha 5 gene cluster in chromosome 15q11-q13 is rich in highly polymorphic (CA)n repeats.

The gamma-aminobutyric acid (GABAA) receptor beta 3 (GABRB3) and alpha 5 (GABRA5) subunit genes have been localized to the Angelman and Prader-Willi syndrome region of chromosome 15q11-q13. GABRB3, which encompasses 250 kb, is located 100 kb proximal of GABRA5, with the two genes arranged in head-to-head transcriptional orientation. In screening 135 kb of cloned DNA within a 260-kb interval extending from within GABRB3 to the 5' end of GABRA5, 10 new (CA)n repeats have been identified. Five of these have been analyzed in detail and found to be highly polymorphic, with the polymorphism information content (PIC) ranging from 0.7 to 0.85 and with heterozygosities of 67 to 94%. In the clones from GABRB3/GABRA5 region, therefore, the frequency of (CA)n with PICs > or = 0.7 is 1 per 27 kb. Previous estimates of the density of (CA)n with PICs > or = 0.7 in the human genome have been approximately 10-fold lower. The GABRB3/GABRA5 region appears, therefore, to be enriched for highly informative (CA)n. This set of closely spaced, short tandem repeat polymorphisms will be useful in the molecular analyses of Prader-Willi and Angelman syndromes and in high-resolution studies of genetic recombination within this region.

High-resolution mapping of the gamma-aminobutyric acid receptor subunit beta 3 and alpha 5 gene cluster on chromosome 15q11-q13, and localization of breakpoints in two Angelman syndrome patients.

The gamma-aminobutyric acid (GABAA) receptors are a family of ligand-gated chloride channels constituting the major inhibitory neurotransmitter receptors in the nervous system. In order to determine the genomic organization of the GABAA receptor beta 3 subunit gene (GABRB3) and alpha 5 subunit gene (GABRA5) in chromosome 15q11-q13, we have constructed a high-resolution physical map using the combined techniques of field-inversion gel electrophoresis and phage genomic library screening. This map, which covers nearly 1.0 Mb, shows that GABRB3 and GABRA5 are separated by less than 100 kb and are arranged in a head-to-head configuration. GABRB3 encompasses approximately 250 kb, while GABRA5 is contained within 70 kb. This difference in size is due in large part to an intron of 150 kb within GABRB3. We have also identified seven putative CpG islands within a 600-kb interval. Chromosomal rearrangement breakpoints--in one Angelman syndrome (AS) patient with an unbalanced translocation and in another patient with a submicroscopic deletion--are located within the large GABRB3 intron. These findings will facilitate chromosomal walking strategies for cloning the regions disrupted by the DNA rearrangements in these AS patients and will be valuable for mapping new genes to the AS chromosomal region.

FISH ordering of reference markers and of the gene for the alpha 5 subunit of the gamma-aminobutyric acid receptor (GABRA5) within the Angelman and Prader-Willi syndrome chromosomal regions.

We have established a probe order within the Angelman/Prader-Willi chromosomal regions by multicolor fluorescence in situ hybridization (FISH). The probe [locus] order extending distally from the centromere is 34[D15S9]-IR4-3R[D15S11]-189-1[D15S13]-PW71++ + [D15S63]-3-21[D15S10]-28 beta 3-H3[GABRB3]-IR10-1 [D15S12]. This order agrees with that recently reported (1) with the exception of PW71 [D15S63]. In addition, a second gamma-aminobutyric acid (GABAA) receptor, the alpha 5 subunit, has been localized within the reference map to between GABRB3 and D15S12. The locus order was further confirmed by DNA hybridization analysis of two patients, one with Angelman syndrome and one with Prader-Willi syndrome, with different unbalanced translocations and molecular extents of deletion. Our results provide a framework map of chromosome 15q11-q13 into which additional markers can be oriented and allow a further differentiation of the critical genetic regions of the two syndromes.

Maternal but not paternal transmission of 15q11-13-linked nondeletion Angelman syndrome leads to phenotypic expression.

Angelman syndrome (AS) may result from either maternally inherited deletions of chromosome 15q11-13 or from paternal uniparental disomy for chromosome 15. This is in contrast to Prader-Willi syndrome (PWS), which is caused by either paternal deletion of this region or maternal disomy for chromosome 15. However, 40% of AS patients inherit an apparently intact copy of chromosome 15 from each parent. We now describe a family in which three sisters have given birth to four AS offspring who have no evidence of deletion or paternal disomy. We show that AS in this family is caused by a mutation in 15q11-13 that results in AS when transmitted from mother to child, but no phenotype when transmitted paternally. These results suggest that the loci responsible for AS and PWS, although closely linked, are distinct.

Chromosome 15 uniparental disomy is not frequent in Angelman syndrome.

Genetic imprinting has been implicated in the etiology of two clinically distinct but cytogenetically indistinguishable disorders--Angelman syndrome (AS) and Prader-Willi syndrome (PWS). This hypothesis is derived from two lines of evidence. First, while the molecular extents of de novo cytogenetic deletions of chromosome 15q11q13 in AS and PWS patients are the same, the deletions originate from different parental chromosomes. In AS, the deletion occurs in the maternally inherited chromosome 15, while in PWS the deletion is found in the paternally inherited chromosome 15. The second line of evidence comes from the deletion of an abnormal parental contribution of 15q11q13 in PWS patients without a cytogenetic and molecular deletion. These patients have two maternal copies and no paternal copy of 15q11q13 (maternal uniparental disomy) instead of one copy from each parent. By qualitative hybridization with chromosome 15q11q13 specific DNA markers, we have now examined DNA samples from 10 AS patients (at least seven of which are familial cases) with no cytogenetic or molecular deletion of chromosome 15q11q13. Inheritance of one maternal copy and one paternal copy of 15q11q13 was observed in each family, suggesting that paternal uniparental disomy of 15q11q13 is not responsible for expression of the AS phenotype in these patients.

Angelman syndrome: three molecular classes identified with chromosome 15q11q13-specific DNA markers.

Angelman syndrome (AS) and Prader-Willi syndrome (PWS) share a cytogenetic deletion of chromosome 15q11q13. To determine the extent of deletion in AS we analyzed the DNA of 19 AS patients, including two sib pairs, with the following chromosome 15q11q13--specific DNA markers: D15S9-D15S13, D15S17, D15S18, and D15S24. Three molecular classes were identified. Class I showed a deletion of D15S9-D15S13 and D15S18; class II showed a deletion of D15S9-D15S13; and in class III, including both sib pairs, no deletion was detected. These molecular classes appear to be identical to those observed in PWS. High-resolution cytogenetic data were available on 16 of the patients, and complete concordance between the presence of a cytogenetic deletion and a molecular deletion was observed. No submicroscopic deletions were detected. DNA samples from the parents of 10 patients with either a class I or a class II deletion were available for study. In seven of the 10 families, RFLPs were informative as to the parental origin of the deletion. In all informative families, the deleted chromosome 15 was observed to be of maternal origin. This finding is in contrast to the paternal origin of the deletions in PWS and is currently the only molecular difference observed between the two syndromes.

Absence of a single repeat from the coding region of the human involucrin gene leading to RFLP.

The human involucrin gene has been mapped to the region q21-q22 of chromosome 1. Three of six Utah families examined were polymorphic for a PstI fragment of the involucrin gene. In one individual, the variant PstI fragment was found by DNA sequencing to be missing one of the 39 repeats that make up two-thirds of the coding region.

Restriction fragment length polymorphisms within proximal 15q and their use in molecular cytogenetics and the Prader-Willi syndrome.

Restriction fragment length polymorphisms (RFLPs) are described in detail for 6 DNA probes (D15S9-13, D15S18) that localize to the proximal long arm of human chromosome 15 (15q11-15q13: this report and Tantravahi et al., Am. J. Med. Genet. 33:78-87. Multiple RFLPs are detected by the probe that identifies locus D15S13, and these RFLPs are shown by genomic mapping to result from a nearby insertion or deletion of 1.8 kilobases (kb) of DNA. This set of RFLPs detected by proximal 15q probes can be used for studies on the Prader-Willi syndrome (PWS) and on mentally retarded individuals with a supernumerary inv dup(15) chromosome. Five of the polymorphic loci (D15S9-13) map to the region implicated in the cause of the PWS (15q11.2-15q12). Each of 4 families tested with these probes, as well as an additional "PWS-like" patient, was informative by RFLP analysis. The two PWS deletions studied, which occurred de novo, were inherited from the chromosome 15 provided by the father. By contrast, the 2 inv dup(15) chromosomes analyzed were of maternal origin. The use of RFLPs can also simplify the molecular determination of copy number in chromosomal aneuploidy, as exemplified by analysis of individuals with the PWS and a deletion, patients with an inv dup(15), and one patient with a more complex rearrangement involving chromosome 15. Our studies demonstrate the application of DNA probes for both molecular cytogenetic studies on this chromosome region and the development of diagnostic molecular markers to aid early clinical diagnosis of the PWS.

Helpline: suicide prevention at a suicide site.

In an effort to reduce the number of suicides from the Mid-Hutson Bridge in Poughkeepsie, New York, the Dutchess County Department of Mental Hygiene and the New York State Bridge Authority jointly established a suicide prevention phone on the bridge, which is directly connected to a 24-hour psychiatric emergency service. This program is the first known one in which a dedicated suicide prevention helpline has been installed at a site of known suicides and linked with a mental health service. After 2 years of operation, the phone has been used 30 times; the data suggest that most would-be jumpers are ambivalent enough about dying that they will reach out for help/contact if the opportunity exists, and, as a consequence, can be saved.