Genetic linkage of familial expansile osteolysis to chromosome 18q

Familial expansile osteolysis is a rare bone dysplasla whichis transmitted as an autosomal dominant trait in a large kindredin Northern Ireland. The gene which causes the disease showstight linkage with several polymorphic markers on chromosome18q with a maximum lod score of 11.53 at a recombination fractionof 0.00 with D18S64. The gene is flanked by D18S35 and D18S61and is located at chromosome 18q21.1–q22. Mapping a newlocus for a gene involved in regulation of bone metabolism mayalso have implications in the study of Paget's disease of bonewhich is a common related bone dysplasla.     

Sequence analysis of 21 genes located in the Kartagener syndrome linkage region on chromosome 15q

Primary ciliary dyskinesia (PCD) is a rare genetic disorder, which shows extensive genetic heterogeneity and is mostly inherited in an autosomal recessive fashion. There are four genes with a proven pathogenetic role in PCD. DNAH5 and DNAI1 are involved in 28 and 10% of PCD cases, respectively, while two other genes, DNAH11 and TXNDC3, have been identified as causal in one PCD family each. We have previously identified a 3.5 cM (2.82 Mb) region on chromosome 15q linked to Kartagener syndrome (KS), a subtype of PCD characterized by the randomization of body organ positioning. We have now refined the KS candidate region to a 1.8 Mb segment containing 18 known genes. The coding regions of these genes and three neighboring genes were subjected to sequence analysis in seven KS probands, and we were able to identify 60 single nucleotide sequence variants, 35 of which resided in mRNA coding sequences. However, none of the variations alone could explain the occurrence of the disease in these patients.     

Genetic analysis of the linkage between chromosome 11q and atopy

Previous work has suggested that there is a genetic predisposition for the development of both asthma and atopy. A recent study has also shown that there is a striking link between chromosome 11q and the IgE response underlying asthma and rhinitis. To further assess the linkage between chromosome 11q and atopy, we have studied nine families of two and, in many instances, three generations with the index case having asthma and/or atopy. Using two restriction fragment length polymorphism probes associated with the regions 11q12-q13.2, namely PYGM and INT2, we have been unable to confirm a significant link between this region of chromosome 11q and atopy as defined by a positive skin-prick test and/or a raised specific IgE and/or a raised total IgE.     

Genetic linkage of the human gene for phenylethanolamine N-methyltransferase (PNMT), the adrenaline-synthesizing enzyme, to DNA markers on chromosome 17q21-q22.

We have determined the genetic location of the human gene encoding phenylethanolamine N-methyltransferase (PNMT), the terminal enzyme of the catecholamine pathway catalyzing the synthesis of epinephrine (adrenaline) from norepinephrine. This gene is linked to DNA markers on the long arm of chromosome 17, q21-q22, most closely to the DNA markers MFD15 (D17S250) (Zmax = 15.0, theta = 0.065) and fLB17.1 (Zmax = 14.6, theta = 0.045). Multipoint linkage analysis placed the PNMT locus in the interval fLB17.1-CMM86 (D17S74), at 4 centiMorgans (cM) distal to fLB17.1, and at 17 cM proximal to CMM86. Mapping of the PNMT gene will provide the basis for genetic linkage studies in families with disease which might pathogenetically involve this enzyme. The human chromosomal region 17q21-22 identified here to harbour the PNMT gene may be syntenic to the chromosomal region in the stroke-prone spontaneously hypertensive rat (SHR-SP) recently linked to blood-pressure regulation. As an increase of PNMT activity has been associated with the development of hypertension in SHR-SP, it will be of interest to perform comparative mapping of the PNMT gene.     

Assignment of the possible HTLV receptor gene to chromosome 17q21-q23

We have determined the HTLV (Human T-cell leukemia virus) receptor localization more precisely on the human chromosome 17. Based on the fact that HTLV infection induces syncytium formation of infected cells as a result of interaction between the viral envelope and viral receptor, we performed the sensitive biological assay using recombinant vaccinia expression system. Our results from the induced syncytium pattern of the somatic hybrid cell lines with different deletions indicated that the HTLV receptor gene may reside from q21 to q23 on the long arm of the human chromosome 17.     

Genetic mapping of the breast-ovarian cancer syndrome to a small interval on chromosome 17q12-21: exclusion of candidate genes EDH17B2 and RARA

A susceptibility gene for hereditary breast-ovarian cancer,BRCA1, has been assigned by linkage analysis to chromosome 17q21.Candidate genes in this region Include EDH17B2, which encodesestradiol 17ß-hydroxysterold dehydrogenase II (17ß-HSDII), and RARA, the gene for retinolc acid receptor     

Exclusion of genetic linkage to 4q21-23 and 17q21 in a family with lewy body parkinsonism

Genetic analysis of markers from chromosomes 4q21-23 and 17q21 in a family with apparently autosomal dominant Lewy body parkinsonism is presented. This analysis shows that the locus leading to this disease is not allelic with that previously shown to lead to Lewy body parkinsonism on chromosome 4 or to the locus on chromosome 17 leading to frontotemporal dementia with parkinsonism. A brief clinical comparison of this family with families showing linkage to these loci is presented. The data suggest that at least one other major genetic determinant for Lewy body parkinsonism remains to be identified. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 81:166–171, 1998. © 1998 Wiley-Liss, Inc.     

Close linkage of PUM and SPTA within chromosome band 1q21

Nine families were examined for linkage on chromosome 1 between the hypervariable gene PUM and the α-spectrin ( SPTA ) gene using DNA probes. Close linkage was found with a maximum lod score of 5.98 at θ= 0.05.
Hybridization to DNA from somatic cell hybrids made from a parent line carrying a balanced X:1 translocation showed both genes to lie proximal to the breakpoint at 1q23. DNA hybridization to cell lines carrying deletions of 1q21–25 showed the presence of two polymorphic alleles for both loci. These results, combined with existing in situ hybridization data, suggest PUM and SPTA both lie within 1q21.
Linkage analysis between PUM and the Duffy blood group ( FY ) gave a maximum lod of 2.15 at θ= 0.15. These data combined with data from another laboratory give a maximum lod of 5.21 for linkage between PUM and FY at θ= 0.10     

Genetic linkage of autosomal dominant neovascular inflammatory vitreoretinopathy to chromosome 11q13.

Autosomal dominant neovascular inflammatory vitreoretinopathy (ADNIV) is an inherited eye disease characterized by retinal and iris neovascularization, abnormal retinal pigmentation, anterior chamber and vitreous inflammation, cystoid macular edema, vitreous hemorrhage, and traction retinal detachment. Some of these clinical features are shared by more common, potentially blinding, conditions including diabetic retinopathy, uveitis, and retinitis pigmentosa. Elucidation of the molecular pathogenesis of ADNIV has the potential to provide insight into the mechanisms of these common disorders. One hundred and sixteen members of an eight generation family affected with ADNIV were examined. A combination of slit lamp biomicroscopy, ophthalmoscopy, and electroretinography was used to establish the diagnosis and 34 family members were found to be affected. Blood samples were obtained from thirty-three of these individuals and nine spouses and used for chromosome linkage analysis with denaturing gradient gel and short tandem repeat polymorphisms. Two markers that map to chromosome 11q13 were found to be significantly linked to the ADNIV phenotype. There were no recombinants between the disease phenotype and marker D11S527 and multipoint analysis yielded a maximum LOD score of 11.9 centered on this marker.     

染色体17q21区域发育性髋关节发育不良易感基因的定位

目的 在染色体17q21区域的D17S1820附近定位发育性髋关节发育不良(developmental dysplasia of the hip,DDH)的易感基因.方法 根据等位基因的数目(≥5)、杂合度(≥0.70)及多态信息含量(≥0.5),在D17S1820附近选择了11个短串联重复序列(short tandem repeat,STR)位点,采用PCR-毛细管电泳的方法,对103个DDH核心家系的309名成员进行基因分型,并进行传递不平衡检验(transmission disequilib rium test,TDT).结果 D17S810和D17S931因不能提供充足的多态信息,未进行TDT检验.其余9个STR多态位点在103个核心家系中的基因型分析结果符合孟德尔遗传模式.TDT检验结果显示,位于两端的D17S1787和D17S787与DDH不存在传递不平衡,而D17S855、D17S858、D17S806、D17S1877、D17S941、D17S752及D17S790与DDH均存在传递不平衡.将DDH易感基因的区域初步定位于D17S855～D17S790之间约11.70 cM的范围内.结论 17号染色体D17S855～D17S790之间约11.70 cM的区域与DDH有关联,在该区域可能存在DDH的易感基因.     

Genetic heterogeneity of Usher syndrome type II: localisation to chromosome 5q

Usher syndrome is a group of autosomal recessive disorders that includes retinitis pigmentosa (RP) with hearing loss. Usher syndrome type II is defined as moderate to severe hearing loss with RP. The USH2A gene at 1q41 has been isolated and characterised. In 1993, a large Usher II family affected with a mild form of RP was found to be unlinked to 1q41 markers. Subsequent linkage studies of families in our Usher series identified several type II families unlinked to USH2A and USH3 on 3q25. After a second unlinked family with many affected members and a mild retinal phenotype was discovered, a genome search using these two large families showed another Usher II locus on 5q (two point lod = 3.1 at D5S484). To date, we have identified nine unrelated 5q linked families (maximum combined multipoint lod = 5.86) as well as three Usher II families that show no significant linkage to any known Usher loci. Haplotype analysis of 5q markers indicates that the new locus is flanked by D5S428 and D5S433. Review of ophthalmological data suggests that RP symptoms are milder in 5q linked families; the RP is often not diagnosed until patients near their third decade. Enamel hypoplasia and severe, very early onset RP were observed in two of the three unlinked families; dental anomalies have not been previously described as a feature of Usher type II.     

Genomewide suggestive linkage of opioid dependence to chromosome 14q

The genetic predisposition to addiction to opioids and other substances is transmitted as a complex genetic trait, which investigators are attempting to characterize using genetic linkage and association. We now report a high-density genome-wide linkage study of opioid dependence. We ascertained 305 DSM-IV opioid dependent affected sibling pairs from an ethnically mixed population of methadone maintained subjects and genotyped their DNA using Affymetrix 10K v2 arrays. Analysis with MERLIN identified a region on chromosome 14q with a non-parametric lod (NPL) of 3.30. Secondary analyses indicated that this locus was relatively specific to the self-identified Puerto Rican subset, as the NPL increased from 3.30 to 5.00 (NPL(Caucasian) = 0.05 and NPL(African Amer.) = 0.15). The 14q peak encompasses the NRXN3 gene (neurexin 3), which was previously identified as a potential candidate gene for addiction. Secondary analyses also identified several regions with gender-specific NPL scores greater than 2.00. The most significant was a peak on (10q) that increased from 0.90 to 3.22 when only males were considered (NPL(female) = 0.05). Our linkage data suggest specific chromosomal loci for future fine-mapping genetic analysis and support the hypothesis that ethnic and gender specific genes underlie addiction susceptibility.     

Exclusion of linkage of Shwachman-Diamond syndrome to chromosome regions 6q and 12q implicated by a de novo translocation

Shwachman-Diamond syndrome is a rare genetic disorder of unknown pathogenesis involving exocrine pancreatic insufficiency and hematological and skeletal abnormalities. There is broad clinical variability; the extent of heterogeneity is unknown but comparisons within a large cohort of patients show no striking differences between patients of families with single or multiple affected offspring. Segregation analysis of a cohort of 69 families has suggested an autosomal recessive mode of inheritance. A single constitutional de novo chromosome rearrangement was reported in a Japanese patient involving a balanced translocation, t(6;12)(q16.2;q21.2), thereby suggesting possible loci for a genetic defect. Evenly spaced microsatellite markers spanning 26–32 cM intervals from D6S1056 to D6S304 and D12S375 to D12S346 were analyzed for linkage in members of 13 Shwachman-Diamond syndrome families with two or three affected children. Two-point lod scores were calculated for each marker under assumptions of recessive inheritance and complete penetrance. Negative lod scores indicated exclusion of both chromosome regions. Further, affected sibs were discordant for inheritance of chromosomes in most families based on constructed haplotypes. The cytogenetic abnormality is not associated with most cases of Shwachman-Diamond syndrome. Am. J. Med. Genet. 85:171–174, 1999. © 1999 Wiley-Liss, Inc.     

Duplication 8q syndrome due to familial chromosome ins(10;8)(q21;q212q22)

We describe a kindred in which an ins(10;8)(q21;q212q22) chromosome rearrangement has been segregating for at least four generations. The risk for balanced carriers to have offspring with duplication of 8q212→8q22 is about 0.31. Individuals with unbalanced chromosomes are mildly to moderately mentally retarded and have a similar unusual appearance. Other manifestations include highly arched or cleft palate (8/9), micrognathia (6/9), sloped shoulders (4–6/9), convulsions (4/9), camptodactyly (3/9), pectus excavatum (2/9), elbow contractures (1/9), and postaxial polydactyly (1/9). The appearance and habitus resemble the mosaic trisomy 8 syndrome, although other anomalies of mosaic trisomy 8, such as vertebral, patellar, and renal defects, were not demonstrated.     

Fine mapping of a region on chromosome 21q21.11-q22.3 showing linkage to type 1 diabetes

Background: Results of a Scandinavian genome scan in type 1 diabetes mellitus (T1D) have recently been reported. Among the novel, not previously reported chromosomal regions showing linkage to T1D was a region on chromosome 21.

Objective: To fine map this region on chromosome 21.

Methods and results: The linked region was initially narrowed by linkage analysis typing microsatellite markers. Linkage was significantly increased, with a peak NPL score of 3.61 (p = 0.0002), suggesting the presence of one or several T1D linked genes in the region. The support interval for linkage of 6.3 Mb was then studied by linkage disequilibrium (LD) mapping with gene based single nucleotide polymorphisms (SNPs). Thirty two candidate genes were identified in this narrowed region, and LD mapping was carried out with SNPs in coding regions (cSNPs) of all these genes. However, none of the SNPs showed association to T1D in the complete material, whereas some evidence for association to T1D of variants of the TTC3, OLIG2, KCNE1, and CBR1 genes was observed in conditioned analyses. The disease related LD was further assessed by a haplotype based association study, in which several haplotypes showed distorted transmission to diabetic offspring, substantiating a possible T1D association of the region.

Conclusions: Although a single gene variant responsible for the observed linkage could not be identified, there was evidence for several combinations of markers, and for association of markers in conditioned analyses, supporting the existence of T1D susceptibility genes in the region.

     

Exclusion of linkage of Shwachman-Diamond syndrome to chromosome regions 6q and 12q implicated by a de novo translocation.

Shwachman-Diamond syndrome is a rare genetic disorder of unknown pathogenesis involving exocrine pancreatic insufficiency and hematological and skeletal abnormalities. There is broad clinical variability; the extent of heterogeneity is unknown but comparisons within a large cohort of patients show no striking differences between patients of families with single or multiple affected offspring. Segregation analysis of a cohort of 69 families has suggested an autosomal recessive mode of inheritance. A single constitutional de novo chromosome rearrangement was reported in a Japanese patient involving a balanced translocation, t(6;12)(q16.2;q21.2), thereby suggesting possible loci for a genetic defect. Evenly spaced microsatellite markers spanning 26-32 cM intervals from D6S1056 to D6S304 and D12S375 to D12S346 were analyzed for linkage in members of 13 Shwachman-Diamond syndrome families with two or three affected children. Two-point lod scores were calculated for each marker under assumptions of recessive inheritance and complete penetrance. Negative lod scores indicated exclusion of both chromosome regions. Further, affected sibs were discordant for inheritance of chromosomes in most families based on constructed haplotypes. The cytogenetic abnormality is not associated with most cases of Shwachman-Diamond syndrome.