Trisomy 19 q.

Two sibs with trisomy for the long arm of chromosome 19 are reported. The common features included flat facial profile with microcephaly, hypertelorism, ptosis, prominence of the glabella, small nose with anteverted nostrils and a characteristic fish-shaped mouth. In addition congenital heart disease, physical retardation and seizures were seen in both sibs. That tristomy 19q can be suspected clinically is emphasized.     

Malformative syndrome associated with a ring 10 chromosome and a translocated 10q/19 chromosome

Summary A male newborn with a ring 10 chromosome is described. The distal part of the long arm of chromosome 10, deleted during ring formation (10q25), is translocated to the short arm of chromosome 19.     

Distal 19q duplication

Summary Two brothers with a distal 19q duplication due to a maternal balanced reciprocal translocation were observed. Clinical features included intrauterine and postnatal growth retardation, microcephaly, and mental retardation with seizures. Dysmorphic facies consisted of coarse hair with a high frontal hairline, short philtrum and nose, flat nasal root, and a broad mouth with downturned commissures. Both routine G-banded and high-resolution prometaphase chromosome studies were employed in evaluation of the family. The dysmorphic features and karyotypes of the affected brothers are compared with those of the two previously reported families with 19q duplication, and a common distal-19q phenotypes is suggested.     

High-resolution cytogenetic characterization of telomeric associations in ring chromosome 19

High-resolution cytogenetic studies of a normal individual with ring chromosome 19 indicate that, at the late-to-mid prophase level of band resolution, no apparent chromosomal material is missing, and that telomeric fusion/association, not deletion, is the cause of the ring chromosome formation. Sub-band analysis of the telomeric fusion shows thin chromatin filaments between the telomeres of some of the very elongated ring chromosomes, which cannot be resolved by metaphase chromosme analysis. The ring chromosome found in this individual shows evidence of the characteristic instability associated with ring chromosomes, including duplicated segments, double rings, and subsequent loss of the ring resulting in cells with monosomy 19. The lack of phenotypic effect and the unstable ring behavior, unlike previously reported patients with ring 19, support the formation of this ring by telomeric association.     

Localisation of the myotonic dystrophy locus to 19q13.2–19q13.3 and its relationship to twelve polymorphic loci on 19q

Summary The order of fourteen polymorphic markers localised to the long arm of human chromosome 19 has been established by multipoint mapping in a set of 40 CEPH (Centre d'Étude de Polymorphisme Humain, Paris) reference families. We report here the linkage relationship of the myotonic dystrophy (DM) locus to twelve of these markers as studied in 45 families with DM. The resulting genetic map is supported by the localisation of the DNA markers in a panel of somatic cell hybrids. Ten of the twelve markers have been shown to be proximal to the DM gene and two, PRKCG and D19S22, distal but at distances of approximately 25 cM and 15 cM, respectively. The closest proximal markers are APOC2 (apolipoprotein C-II) and CKM (creatine kinase, muscle) approximately 3 cM and 2 cM from the DM gene respectively, in the order APOC2-CKM-DM. The distance between APOC2, CKM and DM (of the order of 2 million base pairs) and their known orientation should permit directional chromosome walking and jumping. The data presented here should enable us to determine whether or not new markers are distal to APOC2/CKM and thus potentially flank the DM gene.     

Assignment of the gene encoding DNA ligase I to human chromosome 19q13.2-13.3.

The gene encoding DNA ligase I has been mapped on human chromosome 19 by analysis of rodent-human somatic cell hybrids informative for this chromosome and by two-color fluorescence in situ hybridization. The DNA ligase I gene (LIG1) is localized to 19q13.2-13.3 and is distal to ERCC1, the most telomeric of three DNA repair genes on this chromosome.     

A new variant translocation (19q plus, 22q minus) in chronic myelocytic leukemia

A translocation between chromosome 19 and chromosome 22 was found in one out of nine patients with CML. All the remaining eight patients demonstrated a translocation between chromosomes 9 and 22. The clinical pattern of the disease was similar in the patient with the translocation between chromosomes 19 and 22 and in the other CML patients. Thus the presence of the Ph¹ chromosome appears to be more important for the course and pattern of the disease than the location of the translocated fragment.     

Confirmation of linkage of prostate cancer aggressiveness with chromosome 19q

Regions on chromosomes 7 and 19 were recently reported to contain susceptibility loci that regulate tumor aggressiveness of prostate cancer. To confirm these findings, we analyzed genome scan data from 161 pedigrees affected with prostate cancer. Using the Gleason score as a quantitative measure of tumor aggressiveness, we regressed the squared trait difference, as well as the mean-corrected cross product, on the estimated proportion of alleles shared identical-by-descent at each marker position. Our results confirm the previous linkage results for chromosome 19q (D19S902, P<.00001). In addition, we report suggestive evidence for linkage on chromosome 4 (D4S403, P=.00012). The results of previous findings, together with our results, provide strong evidence that chromosome 19 harbors a gene for tumor aggressiveness.     

An informative panel of somatic cell hybrids for physical mapping on human chromosome 19q.

A panel of 22 somatic cell hybrids divides the q arm of human chromosome 19 into 22 ordered subregions. The panel was characterized with respect to 41 genetic markers. In most cases, a single fragment of chromosome 19 was present in each hybrid. In two cell lines the presence of multiple fragments of the chromosome was demonstrated by segregation of these fragments in subclones. On the basis of the results of marker analysis in this panel, the most likely order of the markers tested is MANB-D19S7-PEPD-D19S9-GPI-C/EBP-TGFB1++ +-(CYP2A,BCKDHA,CGM2,NCA)-PSG1-(D19S8, XRCC1)-(ATP1A3,D19S19)-(D19S37,APOC2)-C KM-ERCC2-ERCC1-(D19S116,D19S117)- (D19S118,D19S119, D19S63,p36.1,D19S112,D19S62,D19S51,D19S54, D19S55)-pW39-D19S6-(D19S50,TNNT1)-D19S2 2-(HRC,CGB,FTL,PRKCG)-qter. This gene order is generally consistent with published physical and genetic mapping orders, although some discrepancies exist. By means of a mapping function that relates the frequency of cosegregation of markers to the distance between them, estimates were made of the sizes, in megabases, of the 19q subregions. The relative physical distances between reference markers were compared with published genetic distances for 19q. Excellent correlation was observed, suggesting that the physical distances calculated by this method are predictive of genetic distances in this region of the genome and, therefore, are just as useful in estimating relative positions of markers.     

Assignment of the human urokinase receptor gene (PLAUR) to 19q13.

Through in situ hybridization of a cDNA probe to metaphase chromosomes, we localized the gene for the human urokinase receptor (PLAUR) on chromosome 19. RBG-banding permitted subchromosomal localization of the PLAUR gene to 19q13.     

cDNA cloning and mapping of the human creatine kinase M gene to 19q13

We describe the first isolation of a human creatine kinase M cDNA clone and its mapping of the gene to human chromosome 19. A human creatine kinase M cDNA clone, pJN2CK-M, harboring a 1,160-bp insert, was isolated by colony hybridization with a previously sequenced chicken creatine kinase M cDNA probe. The human cDNA was used as a probe in Southern transfers of TaqI-digested genomic DNA from mouse/human somatic-cell hybrids to localize the human creatine kinase-M gene to chromosome 19. In situ hybridization of the tritiated cDNA probe to metaphase chromosomes of peripheral blood lymphocytes from normal males revealed significant labeling to chromosome 19. These two independent methodologies assign the human creatine kinase-M gene to chromosome 19. Since greater than 69% of the grains of chromosome 19 label band q13, the human creatine kinase-M gene has been mapped to 19q13. On the basis of high-resolution G-banding, the predominant labeling site was 19q13.2-q13.3.     

Assignment of the urokinase-type plasminogen activator receptor gene (PLAUR) to chromosome 19q13.1-q13.2.

The urokinase-type plasminogen activator receptor (uPAR) is a key molecule in the regulation of cell-surface plasminogen activation and, as such, plays an important role in many normal as well as pathological processes. We applied a cDNA probe from the corresponding gene (PLAUR) in a location analysis using a panel of human/rodent cell hybrids and in a multipoint linkage analysis of 40 CEPH families. These two independent studies both found PLAUR to be located on chromosome 19. The cell hybrid study suggested that PLAUR is located at chromosome 19q13-qter, and the multipoint analysis indicated that PLAUR is located at chromosome 19q13.1-q13.2 and surrounded by DNA markers in the following way (with distances given in recombination fractions): D19S27-.11-CYP2A-.06-PLAUR-.03-D19S8-.04-APOC 2-.24-PRKCG. Further, a ligand-binding study performed on cell hybrids verified the species specificity of the uPAR and confirmed the chromosome assignment.     

Identification of microdeletions spanning the Diamond-Blackfan anemia locus on 19q13 and evidence for genetic heterogeneity.

Diamond-Blackfan anemia (DBA) is a rare pure red-cell hypoplasia of unknown etiology and pathogenesis. A major DBA locus has previously been localized to chromosome 19q13.2. Samples from additional families have been collected to identify key recombinations, microdeletions, and the possibility of heterogeneity for the disorder. In total, 29 multiplex DBA families and 50 families that comprise sporadic DBA cases have been analyzed with polymorphic 19q13 markers, including a newly identified short-tandem repeat in the critical gene region. The results from DNA analysis of 29 multiplex families revealed that 26 of these were consistent with a DBA gene on 19q localized to within a 4.1-cM interval restricted by loci D19S200 and D19S178; however, in three multiplex families, the DBA candidate region on 19q13 was excluded from the segregation of marker alleles. Our results suggest genetic heterogeneity for DBA, and we show that a gene region on chromosome 19q segregates with the disease in the majority of familial cases. Among the 50 families comprising sporadic DBA cases, we identified two novel and overlapping microdeletions on chromosome 19q13. In combination, the three known microdeletions associated with DBA restrict the critical gene region to approximately 1 Mb. The results indicate that a proportion of sporadic DBA cases are caused by deletions in the 19q13 region.     

Detailed Comparative Map of Human Chromosome 19q and Related Regions of the Mouse Genome

One of the larger contiguous blocks of mouse–human genomic homology includes the proximal portion of mouse chromosome 7 and the long arm of human chromosome 19. Previous studies have demonstrated the close relationship between the two regions, but have also indicated significant rearrangements in the relative orders of homologous mouse and human genes. Here we present the genetic locations of the homologs of 42 human chromosome 19q markers in the mouse, with an emphasis on genes also included in the human chromosome 19 physical map. Our results demonstrate that despite an overall inversion of sequences relative to the centromere, apparent “transpositions” of three gene-rich segments, and a local inversion of markers mapping near the 19q telomere, gene content, order, and spacing are remarkably well conserved throughout the lengths of these related mouse and human regions. Although most human 19q markers have remained genetically linked in mouse, one small human segment forms a separate region of homology between human chromosome 19q and mouse chromosome 17. Three of the four rearrangements of mouse versus human 19q sequences involve segments that are located directly adjacent to each other in 19q13.3–q13.4, suggesting either the coincident occurrence of these events or their common association with unstable DNA sequences. These data permit an unusually in-depth examination of this large region of mouse–human genomic homology and provide an important new tool to aid in the mapping of genes and associated phenotypes in both species.     

Assignment of the HOX2 and HOX3 gene clusters to the bovine chromosome regions 19q17-qter and 5q14-23

The homeobox 2 (HOX2) and homeobox 3 (HOX3) clusters have been chromosomally assigned in cattle by in situ hybridization. The probes employed were a murine probe for the mapping of HOX2 to 19q17-qter and human probes for the mapping of HOX3 to 5q14-q23. These assignments confirm the chromosomal assignment of two syntenic groups, consisting of loci located on human chromosome 12 (bovine chromosome 5) and the long arm of human chromosome 17 (bovine chromosome 19).     

Three-point linkage analysis employing C3 and 19cen markers assigns the myotonic dystrophy gene to 19q

Summary In seven large families with myotonic dystrophy (DM) comprising 102 individuals, linkage studies were perfermed employing restriction fragment length polymorphisms in the complement component 3 gene and the 19cen C banding heteromorphism as genetic markers. Three-point linkage analysis excludes DM from the 19cen-C3 segment and strongly supports its assignment to the proximal long arm of chromosome 19.     

The gene for the human IgA Fc receptor maps to 19q13.4

Summary The human gene for the receptor for the Fc portion of IgA has been mapped to chromosome 19, more specifically to 19q13.4, by Southern blot analysis of somatic cell hybrids and in situ hybridization.     

The poliovirus sensitivity (PVS) gene is on chromosome 19q12----q13.2

Sensitivity to nonmodified poliovirus infection is an autosomal dominant trait, specific to primates. The gene for poliovirus sensitivity (PVS) is encoded on human chromosome 19. In order to sublocalize the PVS gene, we infected rodent-human hybrid cell lines that divide human chromosome 19 into four regions with poliovirus 1 and/or 3. When infected, these hybrid cell lines showed the typical cytopathic effect of poliovirus infection only if they contained 19q12----q13.2 as the smallest region of overlap. Appropriate negative and positive controls were used. PVS may be of relevance to myotonic dystrophy (DM) and the inherited motor neuron diseases: to DM because it localizes to the same region of chromosome 19 and to the inherited motor neuron diseases because it encodes a cell-surface receptor expressed on motor neurons.     

Assignment of the growth hormone gene locus to 19q26-qter in cattle and to 11q25-qter in sheep by in situ hybridization

The growth hormone gene locus (GH) of cattle and sheep was mapped to a chromosomal region in each species by using in situ hybridization. The probe employed was an 830-bp cDNA sequence from the ovine growth hormone gene. Based on QFQ chromosome preparations, our results show that the GH locus is on cattle chromosome 19 in the region of bands q26-qter and in sheep on chromosome region 11q25-qter. The GH assignments together with previous localizations of type I cytokeratin genes (KRTA) and one homeobox (HOX2) gene in cattle and one type I cytokeratin gene (KRTA) in sheep identify a strongly conserved chromosomal segment on human chromosome 17, bovine chromosome 19, and sheep chromosome 11.     

Localization of familial benign hypercalcemia, Oklahoma variant (FBHOk), to chromosome 19q13.

Calcium homeostasis by the kidneys and parathyroids is mediated by the calcium-sensing receptor (CaSR), which is located on 3q21-q24 and belongs to family C of the superfamily of G-protein coupled receptors that includes those for metabotropic glutamate, certain pheromones, and gamma-amino butyric acid (GABA-B). Inactivating CaSR mutations result in familial benign hypercalcemia (FBH), or familial hypocalciuric hypercalcemia (FHH), whereas activating mutations result in hypocalcemic hypercalciuria. However, not all FBH patients have CaSR mutations, which, together with the mapping of another FBH locus to 19p13.3, suggests that additional CaSRs or second messengers may be involved. These may be identified by positional cloning, and we therefore performed a genomewide search, using chromosome-specific sets of microsatellite polymorphisms, in an Oklahoma family with an FBH variant (FBHOk), for which linkage to 3q and 19p had been excluded. Linkage was established between FBHOk and eight chromosome 19q13 loci, with the highest LOD score, 6.67 (recombination fraction.00), obtained with D19S606. Recombinants further mapped FBHOk to a <12-cM interval flanked by D19S908 and D19S866. The calmodulin III gene is located within this interval, and DNA sequence analysis of the coding region, the 5' UTR, and part of the promoter region in an individual affected with FBHOk did not detect any abnormalities, thereby indicating that this gene is unlikely to be implicated in the etiology of FBHOk. This mapping of FBHOk to chromosome 19q13 will facilitate the identification of another CaSR or a mediator of calcium homeostasis.