Mapping of the HSD17B2 gene encoding type II 17β-hydroxysteroid dehydrogenase close to D16S422 on chromosome 16q24.1–q24.2

The enzymes of the 17β-hydroxysteroid dehydrogenase (17β-HSD) gene family are responsible for a key step in the formation and degradation of androgens and estrogens: catalyzing the interconversion of 17-ketosteroids and their active 17β-hydroxysteroid counterparts. The structure of human type II 17β-HSD cDNA was recently reported. This enzyme catalyzes the interconversion of Δ⁴-androstenedione and testosterone, androstanedione and dihydrotestosterone, and estrone and 17β-estradiol, whereas type I 17β-HSD catalyzes exclusively the interconversion of estrogens. To locate the HSD17B2 gene, the novel dinucleotide CA repeat sequence found 571 bp downstream from the end of exon 1 was genotyped into eight CEPH reference families by PCR. Two-point linkage analysis was performed between the latter polymorphism and the 2066 microsatellite markers of Généthon. The maximal pairwise lod score (Z_max = 33.3) with a maximal recombination fraction (θ_max) of 0.008 was obtained with the marker D16S422 located on 16q24.1–q24.2. To define further the localization of the HSD17B2 gene, we constructed a high-resolution genetic map of the region flanking the polymorphic HSD17B2 gene including eight Généthon markers. The order of the HSD17B2 gene and markers is qter-D16S516 — D16S504 — D16S507 — D16S505 — D16S511 — [HSD17B2—D16S422]—D16S520—D16S413—tel.     

Human Rod Monochromacy: Linkage Analysis and Mapping of a Cone Photoreceptor Expressed Candidate Gene on Chromosome 2q11

We have performed linkage analysis in eight families with rod monochromacy, an autosomal recessively inherited condition with complete color blindness. Significant linkage was found with markers located at the pericentromeric region of chromosome 2. A maximum lod score of 5.36 was obtained for marker D2S2333 at θ = 0.00. Mapping of meiotic breakpoints localized the disease gene between markers D2S2187 and D2S2229. Homozygosity for a number of subsequent markers indicating identity by descent was found in two families and provides evidence for a further refinement of the locus proximal to D2S373. This defines an interval of ≈3 cM covering theACHM2locus for rod monochromacy. Radiation hybrid mapping of theCNGA3gene encoding the α-subunit of the cGMP gated cation channel in human cone photoreceptors resulted in a maximum lod score of 16.1 with marker D2S2311 combined with a calculated physical distance of 6.19cR_10,000. Screening of the CEPH YAC library and subsequent STS mapping indicated the physical order cen–D2S2222–D2S2175–(D2S2187/D2S2311)–qtel ofmarkers on 2q11 and showed that theCNGA3gene maps most closely to D2S2187 and D2S2311. These data indicate that theCNGA3gene maps within the critical interval of theACHM2locus for rod monochromacy and thus is a candidate gene for this disease.     

Genetic fine localization of the β-glucocerebrosidase (GBA) and prosaposin (PSAP) genes: implications for Gaucher disease

Mutations in the glucocerebrosidase (GBA) and prosaposin (PSAP) genes are responsible for Gaucher disease, the most prevalent sphingolipidosis. Somatic cell hybrid analysis and in situ hybridization experiments have localized the GBA gene to 1q21 and the PSAP gene to 10q21-q22. We performed pairwise and multi-point linkage analyses between the two genes and several highly polymorphic markers from the Généthon human linkage map. Our results show that six markers cosegregate with the GBA gene (Z_max = 8.73 at θ = 0.00 for marker D1S2714) and define a 3.2-cM interval between D1S305 and D1S2624 as the most probable location for the gene. Three of these markers (D1S2777, D1S303, and D1S2140), as well as the gene encoding pyruvate kinase (PKLR), are contained in a single YAC clone together with the GBA gene. A new polymorphism was identified within the PSAP gene (C16045T) and used for linkage studies. The multi-point analysis places the gene in a 9.8-cM interval between D10S1688 and D10S607. The fine localization of these genes provides a useful tool for cosegregation analysis, indirect molecular diagnosis, and population genetic studies. Received: 22 October 1996 / Accepted: 4 February 1997     

Mapping of the Gene for Machado-Joseph Disease within a 3.6-cM Interval Flanked by D14S291/D14S280 and D14S81, on the Basis of Studies of Linkage and Linkage Disequilibrium in 24 Japanese Families

The gene locus of Machado-Joseph disease (MJD) has recently been mapped within a 29-cM subregion of 14q chromosome. We did a linkage study of 24 multigenerational MJD Japanese pedigrees, in an attempt to narrow the candidate region of this gene. Pairwise and multipoint linkage analysis, together with haplotype segregation analysis, led to the conclusion that the MJD gene is located at the 6.8-cM interval between D14S256 and D14S81 (Z_max = 24.78, multipoint linkage analysis). D14S291 and D14S280, located at the center of this interval, showed no obligate recombination with the MJD gene (Z_max = 5.93 for D14S291 and 9.99 for D14S280). A weak, but significant, linkage disequilibrium of MJD gene was noted with D14S81 (P < .05) but not with D14S291 or D14S280. These results suggest that a 3.6-cM interval flanked by D14S291/D14S280 and D14S81 is the most likely location of the MJD gene and that it is closest to D14S81.     

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.     

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.     

CONTIG EXPLORER: Interactive Marker-Content Map Assembly

In STS-content mapping of a region, multiple optimal or near-optimal putative orders of markers exist. Determining which of the markers in this region can be placed reliably on the physical map of the chromosome and which markers lack sufficient evidence to be placed requires software that facilitates exploratory sensitivity analysis and interactive reassembly with different subsets of the input data and that also assists the evaluation of any arbitrary (user-specified) marker order. We describe CONTIG EXPLORER, a package for interactive assembly of STS-content maps that provides the user with various ways of performing such analyses, thereby facilitating the design of laboratory experiments aimed at reducing ambiguity in STS order. We then compare the output of CONTIG EXPLORER with two other assembly programs, SEGMAP and CONTIGMAKER, for a region of chromosome 12p between 21 and 38 cM on the sex-averaged CEPH/Généthon linkage map.     

Genetic and physical map of the interferon region on chromosome 9p.

A region of chromosome 9, surrounding the interferon-beta (IFNB1) locus and the interferon-alpha (IFNA) gene cluster on 9p13-p22, has been shown to be frequently deleted or rearranged in a number of human cancers, including leukemia, glioma, non-small-cell lung carcinoma, and melanoma. To assist in better defining the precise region(s) of 9p implicated in each of these malignancies, a combined genetic and physical map of this region was generated using the available 9p markers IFNB1, IFNA, D9S3, and D9S19, along with a newly described locus, D9S126. The relative order and distances between these loci were determined by multipoint linkage analysis of CEPH (Centre d'Etude du Polymorphisme Humain) pedigree DNAs, pulsed-field gel electrophoresis, and fluorescence in situ hybridization. All three mapping approaches gave concordant results and, in the case of multipoint linkage analysis, the following gene order was supported for these and other closely linked chromosome 9 markers present in the CEPH database: pter-D9S33-IFNB1/IFNA-D9S126-D9S3-D9S19 -D9S9/D9S15-ASSP3-qter. This map serves to extend preexisting chromosome 9 maps (which focus primarily on 9q) and also reassigns D9S3 and D9S19 to more proximal locations on 9p.     

Leaf traits and photosynthetic parameters of saplings and adult trees of co-existing species in a temperate broad-leaved forest

In Central European forestry the establishment of broad-leaved mixed forests is attaining increasing importance, but little information exists about gas exchange characteristics of some of the tree species involved, which are less abundant today. In an old-growth forest in Central Germany (Hainich, Thuringia), (i) I compared morphological and chemical leaf traits that are indicative of leaf gas exchange characteristics among eight co-existing species, and (ii) analysed photosynthetic parameters of saplings and adult trees (lower and upper canopy level) in four of these species (Acer pseudoplatanus L., Carpinus betulus L., Fraxinus excelsior L. and Tilia platyphyllos Scop.).Leaves from the upper canopy in the eight species studied varied significantly in their specific leaf area (12.9–19.4 m² kg⁻¹), stomatal density (125–313 stomata mm⁻²), leaf nitrogen concentration (95–157 mmol N m⁻²) and δ¹³C content (–27.81 to –25.85‰). F. excelsior and C. betulus were largely contrasting species, which suggests that the species, which were studied in more detail, include the widest difference in leaf gas exchange among the co-existing species. The saplings of the four selected species exhibited shade acclimated leaves with net photosynthesis rates at saturating irradiance (A_max) between 5.0 and 6.4 μmol m⁻² s⁻¹. In adult trees A_max of fully sunlit leaves was more variable and ranged from 10.5 (C. betulus) to 16.3 μmol m⁻² s⁻¹ (F. excelsior). However, less negative δ¹³C values in F. excelsior sun leaves point to a strong limitation in gas exchange. In the lower canopy of adult trees A_max of F. excelsior (12.0 μmol m⁻² s⁻¹) was also greater than that of A. pseudoplatanus, C. betulus and T. platyphyllos (5.0–5.6 μmol m⁻² s⁻¹). This can be explained by the small leaf area and the absence of shade leaves in mature F. excelsior trees. Thus, a considerable variation in leaf traits and gas exchange was found among the co-existing tree species. The results suggest that species-specific characteristics increase the spatial heterogeneity of canopy gas exchange and should be taken into account in the interpretation and prediction of gas flux from mixed stands.In der Forstwirtschaft Mitteleuropas gewinnt die Begründung von Laubmischwäldern zunehmend an Bedeutung, aber über Eigenschaften im Gasaustausch einiger beteiligter Baumarten, die heute nicht so häufig sind, ist wenig bekannt. In einem Altbestand in Mitteldeutschland (Hainich, Thüringen) habe ich (i) morphologische und chemische Eigenschaften von Sonnenblättern, die Hinweise auf Charakteristika im Blattgaswechsel geben, an acht koexistierenden Baumarten untersucht, und (ii) Photosyntheseparameter von juvenilen und adulten Bäumen (unteres und oberes Kronenniveau) von vier dieser Arten (Acer pseudoplatanus L., Carpinus betulus L., Fraxinus excelsior L. and Tilia platyphyllos Scop.) erhoben.Blätter aus dem oberen Kronenraum der acht untersuchten Arten variierten signifikant in der spezifischen Blattfläche (12.9–19.4 m² kg⁻¹), der Stomatadichte (125–313 Stomata mm⁻²), dem Blattstickstoffgehalt (95–157 mmol N m⁻²) und den δ¹³C-Werten (–27.81 bis –25.85‰). In diesem Kollektiv zeigten F. excelsior und C. betulus groβe Unterschiede, was darauf hindeutet, dass die Arten, die genauer untersucht wurden, die Spannweite an Gaswechseleigenschaften unter den koexistierenden Baumarten umfassen. Die Jungpflanzen der vier ausgewählten Arten besaßen Schattenblätter, deren Netto-Photosyntheserate bei hoher Lichtintensität (A_max) zwischen 5.0 and 6.4 μmol m⁻² s⁻¹ variierte. An Sonnenblättern von Altbäumen war A_max variabler und lag zwischen 10.5 (C. betulus) und 16.3 μmol m⁻² s⁻¹ (F. excelsior). Allerdings weisen hohe δ¹³C-Werte in Sonnenblättern von F. excelsior auf eine starke Limitierung des Gasaustauschs hin. Auch in der unteren Krone der Altbäume war A_max von F. excelsior (12.0 μmol m⁻² s⁻¹) höher als A_max von A. pseudoplatanus, C. betulus und T. platyphyllos (5.0–5.6 μmol m⁻² s⁻¹). Dies kann durch die geringe Blattfläche und die Abwesenheit von Schattenblättern in der Krone adulter Bäume von F. excelsior erklärt werden. Zwischen den koexistierenden Baumarten wurde somit in Bezug auf Blatteigenschaften und Photosyntheseparameter eine erhebliche Variation festgestellt. Die Ergebnisse legen nahe, dass artspezifische Eigenschaften die räumliche Heterogenität des Gaswechsels im Kronenraum erhöhen und bei der Interpretation und Vorhersage von Gasflüssen über Mischbeständen berücksichtigt werden sollten.     

Refined genetic localization for central core disease

Central core disease (CCO) is an autosomal dominant myopathy clinically distinct from malignant hyperthermia (MHS). In a large kindred in which the gene for CCO is segregating, two-point linkage analysis gave a maximum lod score, between the central core disease locus (CCO) and the ryanodine receptor locus (RYR1), of 11.8, with no recombination. Mutation within RYR1 is responsible for MHS, and RYR1 is also a candidate locus for CCO. A combination of physical mapping using a radiation-induced human-hamster hybrid panel and of multipoint linkage analysis using the Centre d'Etude du Polymorphisme Humain families established the marker order and sex-average map distances (in centimorgans) on the background map as D19S75–(5.2)–D19S9–(3.4)–D19S191–(2.2)–RYR1–(1.7)–D19S190–(1.6)-D19S47–(2.0)–CYP2B. Recombination was observed between CCO and the markers flanking RYR1. These linkage data are consistent with the hypothesis that CCO and RYR1 are allelic. The most likely position for CCO is near RYR1, with a multipoint lod score of 11.4, in 19q13.1 between D19S191 and D19S190, within the same interval as MHS (RYR1).     

A new DNA marker (D4S90) is located terminally on the short arm of chromosome 4, close to the Huntington disease gene

Genetic linkage studies have mapped Huntington's disease (HD) to the distal portion of the short arm of chromosome 4 (4p16.3), 4 cM distal to D4S10 (G8). To date, no definite flanking marker has been identified. A new DNA marker, D4S90 (D5), which maps to the distal region of 4p16.3, is described. The marker was used in a genetic linkage study in the CEPH reference families with seven other markers at 4p16. The study, together with knowledge of the physical map of the region, places D4S90 as the most distal marker, 6 cM from D4S10. A provisional linkage study with HD gave a maximum lod score of 2.14 at a θ of 0.00 and no evidence of linkage disequilibrium. As D4S90 appears to be located terminally, it should play an important role in the accurate mapping and cloning of the HD gene.     

Long range restriction map of the von Hippel-Lindau gene region on human chromosome 3p

Von Hippel-Lindau disease is a heritable tumour syndrome caused by the loss of the function of a tumour suppressor gene on the short arm of human chromosome 3. The interval RAF1-D3S18 (3p25–3p26) has been identfied by genetic linkage studies to harbour the von Hippel-Lindau gene. We have constructed a long range restriction map of this region and have succeeded in demonstrating the physical linkage of loci D3S726 (DNA probe LIB31-38), D3S18 (c-LIB-1, L162E5), D3S601 (LIB1963) and D3S587 (LIB 12–48). Since multipoint analysis has located D3S601 proximal to D3S726, the physical map should be oriented with D3S726 towards the telomere. The order and distances of probes within the von Hippel-Lindau gene region is as follows: telomere — LIB3138 — (<280 kb) — c-LIB-1 — (overlapping) — L162E5 — (900–1600 kb) — (LIB 19-63, LIB 12–48) — centromere. In tissues that included blood, semen and Epstein-Barrvirus-transformed lymphocytes, we detected a putative CpG island flanking D3S18.     

Mapping of the Gene Encoding Human β-Defensin-2 (DEFB2) to Chromosome Region 8p22–p23.1

We recently reported the isolation of human β-defensin-2 (hBD-2), a novel epithelia-derived peptide antibiotic belonging to the β-defensin family. hBD-2 is expressed in skin and epithelia of the airway system, where it is believed to contribute to its antimicrobial defense. By fluorescencein situhybridization using a hBD-2 genomic DNA probe and subsequent fluorescence R-banding, the hBD-2 gene (HGMW-approved symbol DEFB2) was assigned to human chromosome region 8p22–p23.1. PCR with a set of CEPH YAC clones spanning this chromosomal region revealed CEPH YACs 773G4, 920D12, and 820B4 to contain the hBD-2 gene. Relying on the preexisting physical maps of 8p22–p23.1, the hBD-2 gene was mapped in close proximity to D8S1993 (WI-9956) within the interval flanked by D8S552 and D8S1130 (CHLC.GATA25C10). The fact that all currently described genes encoding defensins map to chromosome 8p21–pter suggests that a gene cluster in this chromosomal region may play a major role in antimicrobial defense.     

A New Locus for Dominant “Zonular Pulverulent” Cataract, on Chromosome 13

Inherited cataract is a clinically and genetically heterogeneous disease that most often presents as a congenital autosomal dominant trait. Here we report the linkage of a new locus for dominant “zonular pulverulent” cataract (CZP) to chromosome 13. To map the CZPlocus we performed molecular-genetic linkage analysis using microsatellite markers in a five-generation English pedigree. After exclusion of eight known loci and several candidate genes for autosomal dominant cataract, we obtained significantly positive LOD scores (Z) for markers D13S175 (maximum Z [Z_max] å 4.06; maximum recombination frequency [u_max] å 0) and D13S1236 (Z_max å 5.75, u_max å 0). Multipoint analysis gave Z_maxå 6.62 (u_max å 0) at marker D13S175. Haplotype data indicated that CZP probably lies in the centromeric region of chromosome 13, provocatively close to the gene for lens connexin46.     

Linkage of typical pseudoachondroplasia to chromosome 19

Pseudoachondroplasia (PSACH) is an autosomal dominant dwarfing condition associated with disproportionate short stature, marked joint deformities, and early onset osteoarthritis. Previous linkage studies have excluded linkage to cartilage and noncartilagenous extracellular matrix candidate genes. Here, we report mapping the pseudoachondroplasia gene to chromosome 19. Maximum lod scores of 4.70, 4.15, and 4.86 at θ - 0.00 were found for D19S212, D19S215, and D19S49, respectively. Multipoint analysis suggests the following order: D19S253-D19S199-(D19S212/PSACH/Dl9S215)-D19S222-D19S49.     

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 locus for autosomal dominant reflex epilepsy precipitated by hot water maps at chromosome 10q21.3-q22.3

Hot water epilepsy (HWE) is a form of reflex or sensory epilepsy wherein seizures are precipitated by an unusual stimulus, the contact of hot water over the head and body. Genome-wide linkage analysis of a large family with ten affected members, provided evidence of linkage (Z _max = 3.17 at θ = 0 for D10S412) to chromosome 10q21. Analysis of five additional HWE families, for markers on chromosome 10, further strengthened the evidence of linkage to the same chromosomal region with three out of five families showing concordance for the disease haplotype and providing a two-point LOD score of 4.86 at θ = 0 and 60% penetrance for D10S412. The centromere-proximal and -distal boundaries of the critical genetic interval of about 15 Mb at 10q21.3-q22.3 were defined by D10S581 and D10S201, respectively. Sequence analysis of a group of functional candidate genes, the ion channels KCNMA1, VDAC2 and solute carriers SLC25A16, SLC29A3 revealed no potentially pathogenic mutation. We propose to carry out further analysis of positional candidate genes from this region to identify the gene responsible for this unusual neurobehavioral phenotype.     

Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Ieukoencephalopathy, Genetic Homogeneity, and Mapping of the Locus within a 2-cM Interval

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a recently identified autosomal dominant cerebral arteriopathy characterized by the recurrence of subcortical infarcts leading to dementia. A genetic linkage analysis conducted in two large families recently allowed us to map the affected gene on chromosome 19 in a 12-cM interval bracketed by D19S221 and D19S215. In the present study, these first 2 families and 13 additional ones, including a total of 199 potentially informative meiosis, have been genotyped with eight polymorphic markers located between D19S221 and D19S215. All families were linked to chromosome 19. The highest combined lod score (Z_max = 37.24 at θ = .01) was obtained with marker D19S841, a new CA_n microsatellite marker that we isolated from chromosome 19 cosmids. The recombinant events observed within these families were used to refine the genetic mapping of CADASIL within a 2-cM interval that is now bracketed by D19S226 and D19S199 on 19pl3.1. These data strongly suggest the genetic homogeneity of this recently identified condition and establish the value of its clinical and neuroimaging diagnostic criteria. Besides their importance for the ongoing positional cloning of the CADASIL gene, these data help to refine the genetic mapping of CADASIL relative to familial hemiplegic migraine and hereditary paroxysmal cerebellar ataxia, conditions that we both mapped within the same chromosome 19 region.     

Five new microsatellite polymorphisms at the q21 region of human chromosome 21

Five clones, containing polymorphic CA-repeat sequences, have been isolated from a specific human chromosome 21 phage library and have been localised to band q21 of chromosome 21 using a somatic cell hybrid panel. These highly repetitive sequences (D21S1263, D21S1264, D21S1415, D21S1417 and D21S1420) have been characterised in the CEPH reference parents and have heterozygosities ranging from 0.30 to 0.81 and an average polymorphism information content (PIC) of 0.62. The relative order of these markers, based on the somatic cell hybrid panel, is cen-D21S1417, D21S1420-D21S1263, D21S1415-D21S1264-tel. The most polymorphic marker (D21S1264) has been included in the chromosome 21 genetic map. They have also been localised in the CEPH/ Généthon YAC panel, providing a refined localisation of these polymorphic sequences. These five CA-repeat markers should provide a better characterisation of the q21 region of chromosome 21.