Evidence for a novel glaucoma locus at chromosome 3p21-22

Primary open-angle glaucoma (POAG) is one of the leading causes of blindness in the world. It is a clinically variable group of diseases with the majority of cases presenting as the late onset adult type. Several chromosomal loci have been implicated in disease aetiology, but causal mutations have only been identified in a small proportion of glaucoma. We have previously described a large six-generation Tasmanian family with POAG exhibiting genetic heterogeneity. In this family, approximately one third of affected individuals presented with a glutamine-368-STOP (Q368STOP) mutation in the myocilin gene. We now use a Markov Chain Monte Carlo (MCMC) method to identify a second disease region in this family on the short arm of chromosome 3. This disease locus was initially mapped to the marker D3S1298 and a subsequent minimum disease region of 9 cM between markers D3S1298 and D3S1289 was identified through additional mapping. The region did not overlap with any previously described locus for POAG. Using a multiplicative relative risk model, we identified a positive association between this region and the Q368STOP mutation of myocilin on chromosome 1 in affected individuals. These findings provide evidence of a new autosomal dominant glaucoma locus on the short arm of chromosome 3.     

A gene for universal congenital alopecia maps to chromosome 8p21-22.

Complete or partial congenital absence of hair (congenital alopecia) may occur either in isolation or with associated defects. The majority of families with isolated congenital alopecia has been reported to follow an autosomal-recessive mode of inheritance (MIM 203655). As yet, no gene has been linked to isolated congenital alopecia, nor has linkage been established to a specific region of the genome. In an attempt to map the gene for the autosomal recessive form of the disorder, we have performed genetic linkage analysis on a large inbred Pakistani family in which affected persons show complete absence of hair development (universal congenital alopecia). We have analyzed individuals of this family, using >175 microsatellite polymorphic markers of the human genome. A maximum LOD score of 7.90 at a recombination fraction of 0 has been obtained with locus D8S258. Haplotype analysis of recombination events localized the disease to a 15-cM region between marker loci D8S261 and D8S1771. We have thus mapped the gene for this hereditary form of isolated congenital alopecia to a locus on chromosome 8p21-22 (ALUNC [alopecia universalis congenitalis]). This will aid future identification of the responsible gene, which will be extremely useful for the understanding of the biochemistry of hair development.     

Analysis of p16 expression and allelic imbalance / loss of heterozygosity of 9p21 in cutaneous squamous cell carcinomas

Deletions of the short arm of chromosome 9 have been reported in different types of malignancies. This chromosomal region contains a number of known tumour suppressor genes, including the p16INK4A (CDKN2A), p15INK4B and MTAP tumour suppressor genes located at 9p21. In this study twenty-two paraffin embedded invasive cutaneous SCC were examined for allelic imbalance/ loss of heterozygosity (AI/LOH) of the 9p region (in particular 9p21), and for p16 protein expression. DNA was isolated from microdissected sections of normal and tumour cells and analysed for AI/LOH by using six fluorescently labelled microsatellite markers that map to the 9p region. P16 protein expression was examined by immunohistochemistry. At each of the six microsatellite markers the majority of SCC analysed showed AI/LOH. Overall both AI/LOH within the CDKN2A locus and absence of p16 protein expression were frequent among the cutaneous SCC analysed, suggesting that p16 inactivation may play a role in cutaneous SCC development. The majority of the SCC analysed also had AI/LOH of the marker within the MTAP gene, and at markers flanking the CDKN2A gene; thus further investigation as to a possible role for these genes in the development of cutaneous SCC is warranted.     

Mapping autosomal dominant progressive limb-girdle myopathy with bone fragility to chromosome 9p21-p22: a novel locus for a musculoskeletal syndrome

Progressive myopathy of a limb-girdle distribution and bone fragility is a rare autosomal dominant disorder of unknown etiology. Affected individuals, within this family, present with various combinations of progressive muscle weakness, easy fracturing, and poor healing of long bones. Additional features include premature graying with thin hair, thin skin, hernias, and clotting disorders. Electromyograms show myopathic changes and biopsies reveal non-specific myopathic changes. Skeletal radiographs demonstrate coarse trabeculation, patchy sclerosis, cortical thickening, and narrowing of medullary cavities. We report genetic mapping of this disorder to chromosome 9p21-p22 in a multigenerational family. A genome-wide scan for the disease locus obtained a maximal LOD score of 3.74 for marker GATA87E02 N (D9S1121). Haplotype analysis localized the disease gene within a 15 Mb interval flanked by markers AGAT142P and GATA5E06P. This region also localizes diaphyseal medullary stenosis with malignant fibrous histiocytoma (DMS-MFH). Identification of the disease gene will be necessary to understand the pathogenesis of this complex disorder.Funding for this study is from the National Institutes of Health NIAMS RO1 AR050236-01A1, R03 AR AR46869-03, NINDS K02 NS02157 award, the Muscular Dystrophy Association, Paget Foundation, Children’s Hospital Boston and Shriners Hospitals for Children.     

17p13 (p53 locus), 5q21 (APC locus) and 9p21 (p16 locus) allelic deletions are frequently found in oral exfoliative cytology cells from smoker patients with non-small-cell lung cancer

Molecular cytogenetic and LOH analyses of non-small cell lung cancer (NSCLC) have shown frequent allelic deletions in a variety of chromosomes where tumour suppressor genes are located. Allelic loss at 9p21 (p16 locus), 17p13 (p53) and 5q21(APC) has been frequently described in NSCLC and has also been described in premalignant epithelial lesions of the bronchus and normal bronchial cells. These findings suggest that a tissue field of somatic genetic alterations precedes the histopathological phenotypic changes of carcinoma. Similar changes have been described in oral and laryngeal epithelial tumours associated with smoke exposure. We previously reported frequent LOH at 5q21, 9p21 and TP53 in tumor cells and peritumoral normal bronchial cells from surgically resected NSCLC. We now analyze 96 cases of normal oral exfoliative cytology in which normal epithelial cells were obtained: 43 cases from smoker patients with NSCLC diagnosis, 33 smoker patients with no evidence of malignancy and 20 non-smoker patients with no evidence of tumour. All groups had a similar age and sex distribution. PCR amplification was performed utilising the specific markers D5S346, D9S157 and TP53. In normal oral mucosae cells from patients with NSCLC, we found that 21% of the informative cases showed LOH at any of the three analyzed loci distributed as follows: 14.3% of the informative cases showed LOH at 5q21, 7.7% at 9p21 and 22.2% at TP53. Within the smoker risk group only one case (4% of the informative cases) showed LOH at TP53, while no LOH was found at 5q21 or 9p21. No LOH was found in non-smokers. In conclusion, our results show that a significant number of patients with NSCLC have LOH at TP53, 5q21 and 9p21 in normal oral mucosae, while LOH at these loci is unusual in similar cells obtained from patients with no evidence of malignancy. Our study demonstrates that LOH studies can detect smoker patients with a mutated genotype in normal epithelial cells. Further prospective studies may confirm whether LOH studies can detect patients with a higher risk of NSCLC.     

Parental origin of chromosome 22 loss in sporadic and NF2 neuromas.

It has recently been proposed that the maternally derived chromosome might be preferentially lost in nonfamilial cases of embryonal or early onset malignant tumors. This observation pointed to a potential role of the parental imprinting of the genome during gametogenesis which would be at least partly maintained in the somatic cells. Neuromas are benign tumors that develop from Schwann cells. They occur either sporadically or in individuals that have a genetic predisposition due to neurofibromatosis type 2 (NF2) and usually are multiple. Regardless of the context of occurrence, in approximately 40% of the investigated cases a loss of a chromosome 22 has been documented either by karyotype analysis or by monitoring somatic loss of heterozygosity. We have now examined the parental origin of the chromosome 22 lost in 19 cases of neuromas of patients with unaffected parents among which 11 were non-NF2 patients (sporadic and unique neuroma) and 8 were NF2 patients (bilateral acoustic or multiple neuromas). In both sets of tumors, the lost chromosome 22 can be of either parental origin. A close to threefold preference for the loss of the maternally derived chromosome was observed and should be either confirmed or disproved by studying a larger number of patients.     

Candidate gene polymorphisms and the 9p21 locus in acute coronary syndromes

It is now widely accepted that the classic environmental risk factors for atherosclerosis only partly explain the incidence of coronary artery disease and the development of acute coronary syndromes. Therefore, genetic factors that vary among human populations seem to be involved in the clinical manifestations of such patients. Substantial data suggest that a significant proportion of genetic polymorphisms involved in endothelial function, inflammation, lipid metabolism, thrombosis and fibrinolysis are often present in patients with acute coronary syndromes. In particular, a common variant on chromosome 9p21 was recently identified to affect the risk of myocardial infarction. Here, we review the progress of candidate gene studies and genome-wide association studies in identifying the genetic bases of complex cardiovascular diseases such as acute coronary syndromes.     

Genetic aberration in primary hepatocellular carcinoma：correlation between p53 gene mutation and loss—of—heterozygosity on chromosome 16q21—q23 and 9p21—p23

To elucidate the molecular pathology underlying the development of hepatocellular carcinoma (HCC),we used 41 highly polymorphic microsatellite markers to examine 55 HCC and corresponding non-tumor liver tissues on chromosome 9,16 and 17.Loss-of-heterozygosity(LOH) is observed with high frequency on chromosomal region 17p13(36k/55,65%),9q21-p23(28/55,51%),16q21-23(27/55,49%) in tumors.Meanwhile,microsatellite instability is rarely found in these microsatellite loci.Direct sequencing was performed to detect the tentative mutation of tumor wuppressor genes in these regions:p53,MTS1/p16,and CDH1/E-cadherin.Wihin exon 5-9 of p53 gene,14 out of 55 HCC specimens(24%) have somatic mutations,and nucleotide deletion of this gene is reported in HCC for the first time.Mutation in MTS1/p16 is found only in one tumor case.We do not find mutations in CDH1/E-cadherin.Furthermore,a statistically significant correlation is present between p53 gene mutation and loss of chromosome region 16q21-q23 and 9p21-p23,which indicates that synergism between p53 inactivation and deletion of 16q21-q23 and 9p21-p23 may play a role in the pathogenesis of HCC.     

Identification of a new locus for medullary cystic disease, on chromosome 16p12.

Autosomal dominant medullary cystic disease (ADMCKD) is an interstitial nephropathy that has morphologic and clinical features similar to autosomal recessive nephronophthisis. The typical renal dysfunction associated with ADMCKD results mainly from a defect in urinary concentration ability, although results of urinalysis are normal. Recently, a locus on chromosome 1 was associated with ADMCKD, in DNA from two large Cypriot families, and genetic heterogeneity was inferred. We describe the genomewide linkage mapping of a new locus for medullary cystic disease, ADMCKD2, on chromosome 16p12 in a four-generation Italian pedigree. The family with ADMCKD2 fulfills the typical diagnostic criteria of ADMCKD, complicated by hyperuricemia and gouty arthritis. Marker D16S3036 shows a maximum two-point LOD score of 3.68, and the defined critical region spans 10.5 cM, between D16S500 and SCNN1B1-2. Candidate genes included in the critical region are discussed.     

p53 protein expression and oestrogen and progesterone receptor status in invasive ductal breast carcinomas

p53 protein expression and oestrogen and progesterone receptor status in invasive ductal breast carcinomas The p53 protein expression and oestrogen and progesterone receptors status was investigated in correlation to the grade of malignancy of primary breast carcinomas. Our material constituted imprints from surgical biopsies of 75 invasive ductal breast cancer cases. The p53 protein expression was investigated immunocytologically using the monoclonal antibody p53 DO-7 (DAKO). A biochemical DCC method was applied for the detection of oestrogen and progesterone receptors for all tumours. Fifty-one percent of breast cancer cases were p53 protein positive. A statistically significant association of p53 protein expression and high tumour grade was found (chi2=23.72, d.f.=2, P < 0.001). A statistically significant association was also found between oestrogen and progesterone receptor positive cases and the grade of malignancy (P < 0.001). A negative association between p53 protein expression and oestrogen (ER) and progesterone receptors (PgR) positivity was found. From our results it appears that it is possible to distinguish from grade II tumours two subgroups of cases, one with low malignancy potential and p53 (-), ER (+), PgR (+), and another subgroup with high malignancy potential and phenotype p53 (+), ER (-), PgR (-). The last subset of patients could actually benefit from adjuvant therapy.     

Regional localization of a beta-galactosidase locus on human chromosome 22.

Human white blood cells with an X/22 translocation [46, XX, t(X;22)(q23;q13)] were fused with Chinese hamster cells. The isolated hybrids were analyzed for human chromosomes and 21 enzyme markers. An electrophoretic technique for studying the beta-galactosidase isoenzymes in man-Chinese hamster hybrid cells was developed. Immunological studies showed that the beta-galactosidase marker studied in these hybrids did contain immunological determinants of human origin. Furthermore the results provided evidence that a locus for beta-galactosidase is situated on chromosome 22 distal to the breakpoint in q13.