Stephen F. Kingsmore

Familial antiphospholipid antibody syndrome: Criteria for disease and evidence for autosomal dominant inheritance

OBJECTIVE To develop diagnostic criteria for a familial form of antiphospholipid antibody syndrome (APS), identify families with >1 affected member, examine possible modes of inheritance, and determine linkage to potential candidate genes. METHODS Family members of probands with primary APS were analyzed for clinical and laboratory abnormalities associated with APS. Families with > or =2 affected members were analyzed by segregation analysis and typed for candidate genetic markers. RESULTS Seven families were identified. Thirty of 101 family members met diagnostic criteria for APS. Segregation studies rejected both environmental and autosomal recessive models, and the data were best fit by either a dominant or codominant model. Linkage analysis showed independent segregation of APS and several candidate genes. CONCLUSION Clinical and laboratory criteria are essential to identify the spectrum of disease associated with APS. We believe a set of criteria was developed that can precisely define affected family members with APS. Modeling studies utilizing these criteria strongly support a genetic basis for disease in families with APS and suggest that a susceptibility gene is inherited in an autosomal dominant pattern. However, in these families, APS was not linked with HLA, Fas, or other candidate genes, including beta2-glycoprotein 1, HLA, T cell receptor beta chain, Ig heavy chain, antithrombin III, Fas ligand, factor V, complement factor H, IgK, and Fas.

A 6000 kb segment of chromosome 1 is conserved in human and mouse.

A murine linkage map generated from analyses of 428 meiotic events in an interspecific cross and pulsed field gel electrophoresis allowed examination of the genomic organization of a 6000 kb segment of mouse and human chromosome 1. Analysis of five genes within this syntenic segment of both species revealed striking conservation of gene order, intergenic distance and, to a lesser extent, CpG dinucleotides. In the mouse, meiotic crossover events were not evenly distributed; a hot spot for meiotic recombination was coincident with a CpG‐island. These studies provide a practical approach to aid physical mapping of the human genome and a model for determining the molecular principles that govern meiotic recombination. In addition, these findings demonstrate profound conservation of genomic organization over mammalian evolution.

Characterization of an Atypical Member of the Na+/Cl−-Dependent Transporter Family: Chromosomal Localization and Distribution in GABAergic and Glutamatergic Neurons in the Rat Brain

Abstract: A 3.7‐kb cDNA fragment, designated rat‐XT1, was isolated from a rat whole‐brain cDNA library. The nucleotide sequence of XT1 codes for a 727 amino acid protein with a calculated molecular mass of 81,139 Da and 12 putative transmembrane domains. This protein shares significant homology (28–32%) with the monoamine‐ (dopamine, norepinephrine, serotonin), amino acid‐ (taurine, proline, GABA, glycine), choline‐, and betaine‐, Na+/Cl−‐dependent transporters. The homology is especially high within the first, second, sixth, and eighth transmembrane domains (45–75%). Thus, XT1 clearly belongs to the Na+/Cl−‐dependent neurotransmitter transporter superfamily. However, XT1 may define a new subfamily of transporter because it differs structurally from other members of this family in that the extracellular loop linking transmembrane domains 7 and 8 and the C‐terminal tail are significantly larger in size. Transient or stable expression of rat‐XT1 failed to confer to the transfected cells the ability to transport actively any of the >60 established or putative neurotransmitter substances assessed. Northern blot analyses of peripheral and neural tissues demonstrated that expression of the 8‐kb XT1 mRNA is essentially restricted to the nervous system. In situ hybridization demonstrated a broad but discrete localization of XT1 message in the CNS, particularly in the cerebellum (Purkinje and granular cell layers), the hippocampus (pyramidal and granular cell layers), and the thalamus and throughout the cerebral cortex. This distribution parallels that of the neurotransmitters glutamate and aspartate; however, neither of these excitatory amino acids is a substrate for transport. One noticeable exception to the codistribution of the mRNA for rat‐XT1 and these excitatory neurotransmitters is the cerebellar Purkinje cell layer, in which GABAergic neurons are localized. The gene encoding for XT1 is localized to the mouse chromosome 3 in the vicinity of the locus for the mouse neurological disorder spastic (spa).

CD1 defines conserved linkage group border between human chromosomes 1 and mouse chromosomes 1 and 3

The mouse chromosome to which Ly-38 (CD1) genes map has not been reported. Consequently, the present studies were undertaken to examine the genomic organization of CD1 on human chromosome 1 as well as to identify the Ly-38 (CD1) locus in the mouse

Glycogen synthase: a putative locus for diet-induced hyperglycemia.

Inbred mouse strains fed a diabetogenic diet have different propensities to develop features analogous to type 2 diabetes mellitus. To define chromosomal locations that control these characteristics, recombinant inbred strains from diabetes-prone C57BL/6J (B/6J) and diabetes-resistant A/J strains were studied. Insulin levels and hyperglycemia correlated with two different regions of mouse chromosome 7 (two point LOD scores > 3.0). For insulin levels, 15 of 16 recombinant inbred strains were concordant with a region that contains the tubby mutation that results in hyperinsulinemia. For hyperglycemia, 19 of 23 strains were concordant with the D7Mit25 marker and 20 of 23 strains with the Gpi-1 locus on proximal mouse chromosome 7. Using more stringent criteria for hyperglycemia, 10 of 11 strains characterized as A/J or B/6J like were concordant with D7Mit25. This putative susceptibility locus is consistent with that of the glycogen synthase gene (Gys) recently suggested as a candidate locus by analyses of type 2 diabetes patients. Fractional glycogen synthase activity in isolated muscle was significantly lower in normal B/6J diabetic-prone mice compared with normal diabetic-resistant A/J mice, a finding similar to that reported in relatives of human patients with type 2 diabetes. These data, taken together, raise the possibility that defects in the Gys gene may in part be responsible for the propensity to develop type 2 diabetes.

Physical mapping of a family of interferon-activated genes, serum amyloid P-component, and α-spectrin on mouse chromosome 1

This report defines genetic and physical relationships among α-spectrin (Spna-1), serum amyloid P-component (Sap), and a family of interferon-activated genes, provisionally designatedIfi202, Ifi203, andIfi204. By linkage analysis using a large panel of interspecific backcross mice,Sap, Ifi202, andIfi204 were shown to be tightly linked toSpna-1 on distal mouse chromosome 1. By pulsed field electrophoresis, a genomic restriction map of 6400 kb of distal mouse chromosome 1 was generated, linking genes encodingSap, (Ifi202, Ifi203, Ifi204), andSpna-1 in that order within 450–1000 kb (where the genes within brackets were not ordered). The interferon-activated genesIfi202, Ifi203, andIfi204 were linked within 75–150 kb. Furthermore, genes transcriptionally activated by cytokines, namelySap, Ifi202, Ifi203, andIfi204, were located within 450 kb. These studies suggest the possibility that selective pressure may maintain in physical proximity gene clusters which are under coordinate transcriptional control.

Long-range restriction site mapping of a syntenic segment conserved between human chromosome 1 and mouse chromosome 3

A linkage map determined from segregation analysis of 338 meiotic events in an interspecific mouse cross was utilized to help investigate genomic organization of a linkage group conserved between human chromosome 1p and mouse chromosome 3. Using pulsed-field gel electrophoresis, the genes encoding the lymphocyte adhesion molecule human CD2/murine Ly-37, the alpha 1-subunit of Na, K-ATPase, the beta-subunit of thyrotropin, the beta-subunit of nerve growth factor, and muscle adenylate deaminase were similarly positioned on long-range restriction maps in both species. These studies indicate that the development of detailed genetic maps using interspecific Mus crosses facilitates rapid analysis of murine genomic organization and may enable physical mapping of syntenic regions within the human genome. Moreover, the data suggest profound conservation of genomic organization during mammalian evolution.

Physical linkage of genes encoding the lymphocyte adhesion molecules CD2 and its ligand LFA-3.

The present study was undertaken to determine the physical proximity of LFA3 and CD2 on human chromosome 1. Physical mapping studies of CD2 and LFA3 were undertaken using pulsed field electrophoresis

Genetic mapping of the mouse topoisomerase IIα gene to Chromosome 11

DNA topoisomerase II is a ubiquitous, highly conserved protein that is necessary for DNA metabolism, modulation of chromosome structure, and maintenance of genomic stability (Wang 1991). Mammalian cells contain two isozymes of DNA topoisomerase II, which differ in molecular weight and regulation (Tan et al. 1992). The functional distinction between these topoisomerase II isoforms has not been elucidated. In human, the genes encoding topoisomerase-Ilet and -11[~ have been localized to human Chromosomes (Chrs) 17 and 3, respectively (Tan et al. 1992). The present report describes the genetic mapping of a mouse topoisomerase IIa cDNA (Top2a). The chromosomal location of Top2a was determined with a panel of DNA samples from an interspecific cross that has been characterized for over 500 genetic markers throughout the genome. Restriction fragment length variants (RFLVs) were determined by Southern blot hybridization of DNA from C3H/HeJgld and (C3H/HeJ-gld • Mus spretus)F1 parental mice digested with various restriction endonucleases as previously described (Seldin et al. 1988). Mus spretus was chosen as the second parent because of the relative ease of detection of informative RFLVs in comparison with crosses of inbred strains. The Top2a probe used was a 2.3-kb partial cDNA insert, derived from pMTII 4.2, which was identified from a mouse embryonic cDNA library (Toyoba Company, Japan). The Top2a probe hybridized to an 18.0-kb and 15.0-kb BamHI fragments in C3H/HeJ DNA and to a unique 9.5-kb BamHI fragment in M. spretus DNA. Reference loci used were the genes encoding interleukin 3 (II-3) and avian erythroblastosis oncogene a (Erba). The 11-3 probe, derived from plL3 (Fung et al. 1984), hybridized to a unique 2.5-kb or 1.6-kb PvulI fragment in

Genetic mapping of Pp11r, a thymocyte gene expressed during apoptosis, to mouse Chromosome 15

Apoptosis, or programmed cell deletion, plays a pivotal role in the negative selection of certain cortical thymocytes and thereby in the acquisition of appropriate T cell repertoire. Glucocorticoid treatment can induce apoptosis of immature mouse thymocytes and has provided a model for the examination of molecular events associated with thymocyte apoptosis. The placental protein11-related gene (Ppl 1 r; formerly Tcl-30) is one of several genes identified on the basis of augmented expression during glucocorticoid-induced apoptosis of mouse WEI-II-7TW thymoma cells (Harrigan et al. 1989; Baughman et al. 1992). Although the function of Ppl lr is unknown, thymic expression appears to be restricted to T lymphocyte populations that undergo apoptosis (Harrigan et al. 1989). The present report describes the genetic mapping of Ppl l r to mouse Chromosome (Chr) 15. The chromosomal location of Ppl l r was determined with a panel of DNA samples from an interspecific cross that has been characterized for over 500 genetic markers throughout the mouse genome. Restriction fragment length variants (RFLV) were determined by Southern blot hybridization of DNA from C3H/HeJ-gld and (C3H/HeJ-gld • Mus spretus)F I parental mice digested with various restriction endonucleases as previously described (Seldin et al. 1988). Mus spretus was chosen as the second parent because of the relative ease of detection of informative RFLV in comparison with crosses of inbred strains. The Ppl lr probe used was a PCR product corresponding to bp 126-740 of the Ppl l r cDNA sequence (Baughman et al. 1992), which was identified from a mouse thymus cDNA library (Stratagene, La Jolla, Calif.). The Ppl lr probe hybridized to a unique 1.7 kb or 5.8 kb TaqI fragment in C3H/HeJ or M. spretus DNA, respectively. Reference loci used were the genes encoding