Assignment of congenital cataract Volkmann type (CCV) to chromosome 1p36

Congenital cataract, type Volkmann (McKusick no 115665, gene symbol CCV) is an autosomal dominant eye disease. The disease is characterized by a progressive, central and zonular cataract, with opacities both in the embryonic, fetal and juvenile nucleus and around the anterior and posterior Y-suture. We examined blood samples from 91 members of a Danish pedigree comprising 426 members, by using highly informative short tandem repeat polymorphisms and found the closest linkage of the disease gene (CCV) to a (CA) _n dinucleotide repeat polymorphism at locus D1S243 (Zmax = 14.04 at _M = 0.025 _F = 0.000), at a penetrance of 0.90. Using two additional chromosome 1 markers, we were able to map the CCV gene in the sequence 1pter-(CCV, D1S243)-D1S468-D1S214. The (enolase 1) gene has been mapped to this area; however, a mutation described in this gene did not give eye disease.     

The gene encoding human transmembrane secretory component (locus PIGR) is linked to D1S58 on chromosome 1

The human transmembrane secretory component (SC or poly-Ig receptor, PIGR) is expressed basolaterally on glandular epithelial cells and is responsible for the external translocation of polymeric IgA and IgM. SC is hence a key molecule in antibody protection of mucosal surfaces. The human SC gene (locus PIGR) is located on chromosome 1 (1q31–q41). Here we present the first genetic linkage study of PIGR versus syntenic markers, including D1S58 and F13B, which have been previously regionalized to 1q31–q32 and 1q31–q32.1, respectively. We found that PIGR is closely linked to D1S58 (lods + 5.06 at _max = 0.06, without sex difference). PIGR versus F13B showed + 1.46 at _max = 0.25 for both sexes combined. A recombination of 0.06 between F13B and D1S58 (lods + 2.24) was in contrast to a previously published study giving _max = 0.22 (lods + 3.9), the combined lods being 5.6 at _max = 0.20. The progeny of a triply heterozygotic female indicated that PIGR is the flanking locus, therefore suggesting a cen-F13B-D1S58-PIGR-qter gene sequence on human chromosome 1. Only negative lod scores to RH, C8@, and PGM1 on 1p, and FY on proximal 1q, were found. Current combined Norwegian allele frequencies were estimated for PIGR to be A1 = 0.63, A2 = 0.37 (370 chromosomes), and for D1S58 to be A1 = 0.44, A2 = 0.56 (218 chromosomes).     

A third gene locus for tuberous sclerosis is closely linked to the phenylalanine hydroxylase gene locus

Summary Following the observation of a patient suffering from tuberous sclerosis (TSC) with a de novo reciprocal translocation t(3;12)(p26.3;q23.3), we have undertaken a linkage study in 15 TSC families using polymorphic DNA markers neighbouring the chromosome breakpoints. Significant lod scores have been obtained for markers D12S7 (z _max=2.34, =0.14) and PAH (phenylalanine hydroxylase) (z _max=4.34, =0.0). In multipoint linkage analysis, the peak lod score was 4.56 at the PAH gene locus. These data suggest the existence of a third gene locus for TSC (TSC3) on chromosome 12q22-24.1. The regions that have been found to be linked to TSC in different families map to the positions of three enzymes, phenylalanine hydroxylase (12q22-24), tyrosinase (11q14-22), and dopamine-beta-hydroxylase (9q34), all of which are involved in the conversion of phenylalanine to catecholamine neurotransmitters or melanin. Disorders of these biochemical pathways might be involved in the pathogenesis of TSC.     

DFNB48, a new nonsyndromic recessive deafness locus, maps to chromosome 15q23-q25.1

Nonsyndromic deafness locus (DFNB48) segregating as an autosomal recessive trait has been mapped to the long arm of chromosome 15 in bands q23-q25.1 in five large Pakistani families. The deafness phenotype in one of these five families (PKDF245) is linked to D15S1005 with a lod score of 8.6 at =0, and there is a critical linkage interval of approximately 7 cM on the Marshfield human genetic map, bounded by microsatellite markers D15S216 (70.73 cM) and D15S1041 (77.69 cM). MYO9A, NR2E3, BBS4, and TMC3 are among the candidate genes in the DFNB48 region. The identification of another novel nonsyndromic recessive deafness locus demonstrates the high degree of locus heterogeneity for hearing impairment, particularly in the Pakistani population.     

Genetic fine localization of the arrestin (S-antigen) gene 4 cM distal from D2S172

Arrestin is a component of the light transduction cascade that takes place in the outer segment of retinal rods. In situ hybridization and linkage analysis have localized the arrestin gene to a region of 50 cM between CRYG and D2S23/D2S55 on chromosome 2q24–37. We have performed pairwise and multipoint linkage analysis between arrestin and four highly polymorphic markers from this region. The results indicate tight linkage between the gene and the microsatellite D2S172 (Z _max = 9.25 at =0.038). This fine localization of the gene should provide a useful tool for cosegregation analyses involving the arrestin gene.     

Closing in on the BPES gene on 3q23: mapping of a de Novo reciprocal translocation t(3;4)(q23;p15.2) breakpoint within a 45-kb cosmid and mapping of three candidate genes, RBP1, RBP2, and beta'-COP, distal to the breakpoint

BPES is a genetic disorder presenting with blepharophimosis, ptosis of the eyelids, epicanthus inversus, and telecanthus. BPES type I is associated with female infertility, whereas type II presents without additional symptoms. Hitherto, it remains unknown whether BPES type I results from a defect in a single gene or from a contiguous gene syndrome. Previous cytogenetic and linkage analyses have assigned a BPES locus to 3q23, in a 5-cM interval between D3S1615 and D3S1316. In this report, we describe the molecular and physical characterization of the 3q23 breakpoint in a BPES patient with a t(3;4)(q23;p15.2) translocation. Eight YACs located around and within the D3S1615-D3S1316 interval were mapped relative to the 3q23 breakpoint; 5 YACs spanning the 3q23 breakpoint were identified. Thirteen STSs and ESTs were localized on the YAC map. Subsequent hybridization of 2 YACs spanning the breakpoint to the Human RPCI1 PAC Library and the Human Chromosome 3 LLNL Cosmid Library resulted in the identification of 12 PACs and 50 cosmids respectively, allowing the construction of a detailed PAC and cosmid physical map. A refined position-telomeric to the breakpoint-of 3 candidate genes, cellular retinol-binding proteins 1 and 2 (RBP1, RBP2) and the coatomer beta' subunit (beta'-COP), was obtained on this physical map. Furthermore, a PAC and cosmid contig encompassing the breakpoint was constructed. PAC 169-C 10 and cosmid 11-L 10 crossing the breakpoint have sizes of 110 and 45 kb, respectively. The isolation of coding sequences in these clones and in the rest of the contig will greatly facilitate further efforts toward positional cloning of the gene(s) involved in BPES.     

Restoration of the wild-type locus in an RuBP carboxylase/oxygenase mutant of Synechocystis PCC 6803 via targeted gene recombination.

Summary The interaction between homologous DNA sequences, distant from each other in the chromosome, was examined in the cyanobacterium Synechocystis PCC 6803. Most of the rbcL gene encoding the large subunit of ribulose bisphosphate carboxylase/oxygenase (Rubisco) was duplicated in the genome by a targeted insertion of a 3-truncated gene copy into the psbA-I locus. Both rbcL genes, in the psbA-I region and at the rbc locus, were non-functional; The former due to the 3 truncation, and the latter due to a deletion in the 5-region (creating a 5 truncation) and a mutation associated with an insertion of the Rhodospirillum rubrum rbc gene, yielding a high-CO₂-requiring mutant (cyanorubrum). The 3 and the 5 truncated rbcL genes were linked to chloramphenicol and kanamycin resistance markers, respectively. Decreasing the kanamycin selective pressure concomitantly with exposure of the double resistance mutant to air, resulted in air-growing colonies. Analysis of their genomes, Rubisco proteins, and their ultrastructure revealed: 1) Reconstitution of a full-length cyanobacterial rbcL gene at the rbc locus; 2) simultaneous synthesis of the cyanobacterial (L₈S₈) and R. rubrum L₂) enzymes in meroploids containing both mutated and reconstituted rbcL genes; 3) reappearance of carboxysomes. Our results indicate extensive recombinatorial interactions between the homologous sequences at both loci leading to reconstitution of the cyanobacterial rbcL gene.     

No evidence of genetic heterogeneity in Crouzon craniofacial dysostosis

Crouzon craniofacial dysostosis (CFD) is an autosomal dominant form of craniosynostosis characterized by an abnormal skull shape, with hypertelorism, prominent eyes and midfacial retrusion. Recently, a gene for CFD has been mapped to chromosome 10q25-q26 and mutations in exon B of the fibroblast growth factor receptor 2 (FGFR2) gene have been identified. Here, we report the mapping of a CFD gene to chromosome 10q by close linkage to probe AFMa197wbl at locus D10 S1483 in six unrelated families of French ancestry (Z _max = 4.69 at = 0) and provide additional evidence of genetic homogeneity of this condition. In addition, we report a novel mutation in exon B of the FGFR2 gene (Cys 342 Trp) in familial CFD and describe recurrent mutations at codon 342 as a particularly frequent event in CFD. Since mutations in the extracellular domain of the FGFR2 gene are observed in a few clinically distinct craniosynostosis syndromes (CFD, Jackson-Weiss, Apert and Pfeiffer), the present study gives support to the variable clinical expression of FGFR2 mutations in humans.     

Evidence That the Saethre-Chotzen Syndrome Locus Lies between D7S664 and D7S507, by Genetic Analysis and Detection of a Microdeletion in a Patient

The locus for Saethre-Chotzen syndrome, a common autosomal dominant disorder of craniosynostosis and digital anomalies, was previously mapped to chromosome 7p between D7S513 and D7S516. We used linkage and haplotype analyses to narrow the disease locus to an 8-cM region between D7S664 and D7S507. The tightest linkage was to locus D7S664 ( = 7.16, θ = .00). Chromosomes from a Saethre-Chotzen syndrome patient with t(2;7) (p23;p22) were used for in situ hybridization with YAC clones containing D7S664 and D7S507. The D7S664 locus was found to lie distal to the 7p22 breakpoint, and the D7S507 locus was deleted from the translocation chromosomes. These genetic and physical mapping data independently show that the disease locus resides in this interval.     

Autosomal dominant cerebellar ataxia type I in Martinique (French West Indies): Genetic analysis of three unrelated SCA2 families

Autosomal dominant cerebellar ataxias (ADCAs) are a group of neurodegenerative disorders that are clinically and genetically heterogeneous. We report here a genetic linkage study, with five chromosome 12q markers, of three Martinican families with ADCA type I, for which the spinocerebellar ataxia 1 (SCA1) locus was excluded. Linkage to the SCA2 locus was demonstrated with a maximal lod score of 6.64 at = 0.00 with marker D12S354. Recombinational events observed by haplotype reconstruction demonstrated that the SCA2 locus is located in an approximately 7-cM interval flanked by D 12S 105 and D12S79. Using thez _max-l method, multipoint analysis further reduced the candidate interval for SCA2 to a region of 5 cM. Two families shared a common haplotype at loci spanning 7 cM, which suggests a founder effect, whereas a different haplotype segregated with the disease in the third family. Finally, a mean anticipation of 12 ± 14 years was found in parent-child couples, with no parental sex effect, suggesting that the disease might be caused by an expanded and unstable triplet repeat.     

Molecular Genetic Analysis of Essential Tremor

Essential tremor (ET) is the most common extrapyramidal disorder of the central nervous system with autosomal dominant transmission in the majority of cases and age-dependent penetrance of the mutant gene. In a number of cases, it shares some phenotypic features with autosomal dominant idiopathic torsion dystonia (locusDYT1on chromosome 9q32–34) and is genetically heterogeneous: distinct variants of ET were mapped to chromosomes 3q13 (ETM1) and 2p22–25 (ETM2). We performed studies of candidate loci in a group of Slavonic (11 patients) and Tajik (19 patients) families with ET. Mutational analysis of the DYT1 gene in probands did not reveal the major deletion 946–948delGAG characteristic of idiopathic torsion dystonia, which allows one to genetically distinguish the studied hereditary forms of ET and torsion dystonia. Based on analysis of genetic linkage in informative Tajik pedigrees with ET, linkage to locus ETM1 on chromosome 3q13 was established in four families. Maximum pairwise Lod score was 2.46 at recombination fraction of = 0.00; maximum combined multipoint Lod score was 3.35 for marker D3S3515 and a common mutant haplotype for markers D3S3620, D3S3576, and D3S3720 allowed us to locate a mutant gene in a relatively narrow chromosome region spanning 2 cM. In one informative pedigree with ET, both candidate loci ETM1 and ETM2 were definitely excluded on the basis of negative Lod scores obtained by linkage estimations, which testifies to the existence of another distinct gene for autosomal dominant ET.     

Quantitative studies on the mating system of opium poppy (Papaver somniferum L.)

Summary Nearly 400 individuals at two locations and over a number of years were crossed and subsequently scored for selfing versus outcrossing in eight monohybrid populations of opium poppy (Papaver somniferum). Two different marker loci, petal colour (R/r) and capsule size (B/b) were used to determine the male gametes that had effected fertilizations in F₂ recessives (rr and bb). The estimates of the outcrossing parameter were found to vary with year, location and for the marker locus used ( range: 0.0988–0.3704). Study of two dihybrid crosses involving the two loci simultaneously, further confirmed that outcrossing at the R/r locus was significantly greater than that at the B/b locus. The nature of the outcrossing was, in general, nonrandom. Selfmg predominated in this species; however, there was a high frequency of natural outcrossing for generating variations in P. somniferum.CIMAP publication No. 1086     

Icelandic families with autosomal dominant polycystic kidney disease: families unlinked to chromosome 16p13.3 revealed by linkage analysis

We have mainly used 3 highly polymorphic DNA markers, 3HVR (D16S85), 16AC2.5 (D16S291) and SM7 (D16S283), flanking the PKD1 region on chromosome 16p13.3 to establish linkage status in seven Icelandic families with autosomal dominant polycystic kidney disease (ADPKD). In four families, the disease locus is in the PKD1 region, and three families are unlinked to chromosome 16p13.3. In one of the unlinked families, the disease locus is excluded from a part of the long arm of chromosome 2, and we support a theory of more than 2 loci being responsible for ADPKD. Our data confirm the location of the locus YNH24 (D2S44) to chromosome 2q13-q24.     

Assignment of the gene for central core disease to chromosome 19

Summary In a large kindred in which the gene for central core disease is segregating, we have demonstrated linkage between the disorder and a marker on chromosome 19q. Marker D19S9 (p1J2) was linked to central core disease with a lod score of 6.4 at = 0.03 (support interval 0.01–0.14) thus localizing the gene for this disorder in or very close to 19q12–q13.2.     

Germinal Excision and Reinsertion Frequencies of the Mobile Element Ds Transposed from Two Unlinked T-DNA Loci in Tomato

Acceptor sites of unlinked transposed Ds element from two T-DNA loci in tomato were mapped. Experimental data obtained from TC₁ progeny testing were employed for estimation of germinal excision frequency (GEF) of Ds element and frequency of its reinsertion (FR). The donor T-DNAs 1481J and 1601D, containing a 35S:NPT transformation marker, a 35S:BAR or nos:BAR excision marker conferring phosphinothricine resistance and a Ds element in the 5 untranslated leader of the nos (or 35S): BAR gene, were located on chromosome 7 and 8, respectively. Ds transposition was induced by 105121 T-DNA carrying stabilized Ac (sAc) which provides a source of transposase and 2:GUS marker conferring -glucuronidase activity. Tomato plants harbouring the Ds in 1481J or 1601D locus and sAc were crossed and F₁D, were crossed individually as seed parents to wild-type plants to generate TC₁ progenies. TC₁ seed was germinated on phosphinothricine (Basta)-containing medium, and individual seedlings carrying a transposed Ds and lacking sAc were identified by PCR (to detect the Ds) on phosphinothricine resistant individuals that lacked -glucuronidase activity. From segregation ratio in TC₁ the germinal excision and reinsertion frequencies of the Ds element were estimated for individual F₁ plants. A total of 14560 TC₁ seedlings of 1481J and 16195 TC₁ seedlings of 1601D was analyzed. We observed high variation between individual plants as regards both GEF and FR despite of donor locus (1481J or 1601D), however, the average germinal excision frequencies as well as average frequencies of reinsertion were very similar for both donor loci: GEF_1481J = 24 %, GEF_1501D = 25 %, FR_1481J = 42 %, FR_1601D = 46 %.     

Uncharged tRNA inhibits guanosine 3'',5''-bis (diphosphate) 3''-pyrophosphohydrolase [ppGppase], the spoT gene product, from Escherichia coli

Summary The spoT gene product from Escherichia coli, the guanosine 3,5-bis(diphosphate) 3-pyrophosphohydrolase [ppGppase] catalyzes the specific release of pyrophosphate from the 3-position of guanosine 3,5-bis(diphosphate) [ppGpp]; this reaction is significantly inhibited in the presence of uncharged tRNA _yeast ^Phe . Little or no inhibition is observed with Phe-tRNA^Phe, tRNA^Phe-CpCpA_oxi-red or ribosomal RNA (16S and 23S).     

A new polymorphic marker (D10S97) tightly linked to the multiple endocrine neoplasia type 2A (MEN2A) locus

Familial multiple endocrine neoplasia type 2A (MEN 2A) is a cancer syndrome that is inherited as an autosomal dominant with high penetrance. Its clinical features are medullary carcinoma of the thyroid, pheochromocytomas, and hyperparathyroidism. A new polymorphic locus D10S97 (probe: KW6SacI) detects a codominant EcoRI polymorphism that is tightly linked to the MEN2A locus. The peak lod score for linkage between D10S97 with MEN2A is 13.03 at =0.00. The polymorphic locus D10S97 maps, by linkage analysis, into the previously defined interval between FNRB and RBP3 to which MEN2A has been assigned. We present physical mapping data showing that the probe pKW6 originates from 10p13 and that the polymorphic locus D10S97 in 10q11.2 is detected by cross-hybridization.     

Negative-ion fast atom bombardment tandem mass spectrometry for characterization of sulfated unsaturated disaccharides from heparin and heparan sulfate

Negative-ion fast atom bombardment tandem mass spectrometry has been used in the characterization of non-, mono-, di- and trisulfated disaccharides from heparin and heparan sulfate. The positional isomers of the sulfate group of monosulfated disaccharides were distinguished from each other by negative-ion fast atom bombardment tandem mass spectra, which provide an easy way of identifying the positional isomers. This fast atom bombardment collision induced dissociation mass spectrometry/mass spectrometry technique was also applied successfully to the characterization of di- and trisulfated disaccharides.Abbreviations FABMS fast atom bombardment mass spectrometry - CID collision induced dissociation - MIKE mass analysed ion kinetic energy - MS/MS mass spectrometry/mass spectrometry - HPLC high performance liquid chromatography - UA d-gluco-4-enepyranosyluronic acid - CS chondroitin sulfate - DS dermatan sulfate - HA hyaluronan - Hep heparin - HS heparan sulfate - UA(14) GlcNAc 2-acetamido-2-deoxy-4-O-(-d-gluco-4-enepyranosyluronic acid)-d-glucose - UA(14)GlcNAc6S 2-acetamido-2-deoxy-4-O-(-d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-glucose - UA2S(14)GlcNAc 2-acetamido-2-deoxy-4-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-d-glucose - UA2S(14)GlcNAc6S 2-acetamido-2-deoxy-4-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-glucose - UA(14)GlcN6S 2-amino-2-deoxy-4-O-(-d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-glucose - UA2S(14)GlcN 2-amino-2-deoxy-4-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-d-glucose - UA2S(14)GlcN6S 2-amino-2-deoxy-4-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-glucose - UA(14)GlcNS 2-deoxy-2-sulfamino-4-O-(-d-gluco-4-enepyranosyluronic acid)-d-glucose - UA(14)GlcNS6S 2-deoxy-2-sulfamino-4-O-(-d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-glucose - UA2S(14)GlcNS 2-deoxy-2-sulfamino-4-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-d-glucose - UA2S(14)GlcNS6S 2-deoxy-2-sulfamino-4-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-glucose - UA(13)GalNAc 2-acetamido-2-deoxy-3-O-(-d-Gluco-4-enepyranosyluronic acid)-d-galatose - UA(13)GalNAc4S 2-acetamido-2-deoxy-3-O-(-d-gluco-4-enepyranosyluronic acid)-4-O-sulfo-d-galactose - UA(13)GalNAc6S 2-acetamido-2-deoxy-3-O-(-d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-galactose - UA2S(13)GalNAc 2-acetamido-2-deoxy-3-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-d-galactose - UA2S(13)GalNAc4S 2-acetamido-2-deoxy-3-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-4-O-sulfo-d-galactose - UA2S(13)GalNAc6S 2-acetamido-2-deoxy-3-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-galactose - UA(13)GalNAcDiS 2-acetamido-2-deoxy-3-O-(-d-gluco-4-enepyranosyluronic acid)-4,6-di-O-sulfo-d-galactose - UA(13)GlcNAc 2-acetamido-2-deoxy-3-O-(-d-gluco-4-enepyranosyluronic acid)-d-glucose.     

Autosomal dominant retinitis pigmentosa: a new multi-allelic marker (D3S621) genetically linked to the disease locus (RP4)

Summary We report the characterization of a new eightallele microsatellite (D3S621) isolated from a human chromosome 3 library. Two-point and multi-locus genetic linkage analysis have shown D3S621 to co-segregate with the previously mapped RP4 ( _m=0.12, Z _m=4.34) and with other genetic markers on the long arm of the chromosome, including D3S14 (R208) ( _m=0.00, Z _m= 15.10), D3S47 (C17) ( _m=0.11, Z _m=4.95), Rho ( _m= 0.07, Z _m=1.37), D3S21 (L182) ( _m=0.07, Z _m=2.40) and D3S19 (U1) ( _m=0.13, Z _m=2.78). This highly informative marker, with a polymorphic information content of 0.78, should be of considerable value in the extension of linkage data for autosomal dominant retinitis pigmentosa with respect to locii on the long arm of chromosome 3.     

Inheritance of high oleic acid content in the seed oil of soybean mutant M23

A mutant line, M23, of soybean [Glycine max (L.) Merr.] was found to have two fold increases in oleic acid content in the seed oil compared with the original variety, Bay. Our objective was to determine the inheritance of the high oleic acid content in this mutant. Reciprocal crosses were made between M23 and Bay. There were no maternal and cytoplasmic effects for oleic acid content. The F₁ seeds and F₁ plants were significantly different from either parents or the midparent value, indicating partial dominance of oleic acid content in these crosses. The oleic acid content segregated in the F₂ seeds and F₂ plants in a trimodal pattern with normal, intermediate and high classes, satisfactorily fitting a 121 ratio. The seeds of a backcross between M23 and F₁ segregated into intermediate and high classes in a ratio of 11. These results indicated that oleic acid content was controlled by two alleles at a single locus with a partial dominant effect. Thus, the allele in M23 was designated ol and the genotypes of M23 and Bay were determined to be olol and 0l0l, respectively. The oleic acid contents of the F₂ seeds and F₂ plants were inversely related with the linoleic acid content which segregated in a trimodal pattern with normal, intermediate and low classes in a 121 ratio. Thus, it was assumed that the low linoleic acid content in M23 was also controlled by the ol alleles. Because a diet with high oleic acid content reduces the content of low density lipoprotein cholesterol in blood plasma, the mutant allele, ol, would be useful in improving soybean cultivars for high oleic acid content.