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51.
Predominance of null mutations in ataxia-telangiectasia 总被引:15,自引:4,他引:15
Gilad S; Khosravi R; Shkedy D; Uziel T; Ziv Y; Savitsky K; Rotman G; Smith S; Chessa L; Jorgensen TJ; Harnik R; Frydman M; Sanal O; Portnoi S; Goldwicz Z; Jaspers NG; Gatti RA; Lenoir G; Lavin MF; Tatsumi K; Wegner RD; Shiloh Y; Bar-Shira A 《Human molecular genetics》1996,5(4):433-439
Ataxia-telangiectasia (A-T) is an autosomal recessive disorder involving
cerebellar degeneration, immunodeficiency, chromosomal instability,
radiosensitivity and cancer predisposition. The responsible gene, ATM, was
recently identified by positional cloning and found to encode a putative
350 kDa protein with a Pl 3-kinase-like domain, presumably involved in
mediating cell cycle arrest in response to radiation-induced DNA damage.
The nature and location of A-T mutations should provide insight into the
function of the ATM protein and the molecular basis of this pleiotropic
disease. Of 44 A-T mutations identified by us to date, 39 (89%) are
expected to inactivate the ATM protein by truncating it, by abolishing
correct initiation or termination of translation, or by deleting large
segments. Additional mutations are four smaller in-frame deletions and
insertions, and one substitution of a highly conserved amino acid at the Pl
3-kinase domain. The emerging profile of mutations causing A-T is thus
dominated by those expected to completely inactivate the ATM protein. ATM
mutations with milder effects may result in phenotypes related, but not
identical, to A-T.
相似文献
52.
53.
Recessively inherited L-DOPA-responsive parkinsonism in infancy caused by a point mutation (L205P) in the tyrosine hydroxylase gene 总被引:4,自引:0,他引:4
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56.
Characterization of melanocyte stimulating hormone receptor variant alleles in twins with red hair 总被引:7,自引:3,他引:7
The association between MSHR coding region variation and hair colour in
humans has been examined by genotyping 25 red haired and 62 non-red
Caucasians, all of whom were 12 years of age and members of a twin pair
study. Twelve amino acid substitutions were seen at 11 different sites,
nine of these being newly described MSHR variants. The previously reported
Val92Met allele shows no association with hair colour, but the three
alleles Arg151Cys, Arg160Trp and Asp294His were associated with red hair
and one Val60Leu variant was most frequent in fair/blonde and light brown
hair colours. Variant MSHR genotypes are associated with lighter skin types
and red hair (P < 0.001). However, comparison of the MSHR genotypes in
dizygotic twin pairs discordant for red hair colour indicates that the MSHR
gene cannot be solely responsible for the red hair phenotype, since five of
13 pairs tested had both haplotypes identical by state (with three of the
five having both identical by descent). Rather, it is likely that
additional modifier genes exist, making variance in the MSHR gene necessary
but not always sufficient, for red hair production.
相似文献
57.
Apoptotic cell death in mouse models of GM2 gangliosidosis and observations on human Tay-Sachs and Sandhoff diseases 总被引:5,自引:2,他引:5
Huang JQ; Trasler JM; Igdoura S; Michaud J; Hanal N; Gravel RA 《Human molecular genetics》1997,6(11):1879-1885
Tay-Sachs and Sandhoff diseases are autosomal recessive neurodegenerative
diseases resulting from the inability to catabolize GM2 ganglioside by
beta-hexosaminidase A (Hex A) due to mutations of the alpha subunit
(Tay-Sachs disease) or beta subunit (Sandhoff disease) of Hex A. Hex B
(beta beta homodimer) is also defective in Sandhoff disease. We previously
developed mouse models of both diseases and showed that Hexa-/- (Tay-Sachs)
mice remain asymptomatic to at least 1 year of age while Hexb-/- (Sandhoff)
mice succumb to a profound neurodegenerative disease by 4-6 months of age.
Here we find that neuron death in Hexb-/- mice is associated with apoptosis
occurring throughout the CNS, while Hexa-/- mice were minimally involved at
the same age. Studies of autopsy samples of brain and spinal cord from
human Tay-Sachs and Sandhoff diseases revealed apoptosis in both instances,
in keeping with the severe expression of both diseases. We suggest that
neuron death is caused by unscheduled apoptosis, implicating accumulated
GM2 ganglioside or a derivative in triggering of the apoptotic cascade.
相似文献
58.
1. We have studied the responses to light, conduction down the axons, and anatomical projections of the photoreceptors of the lateral eye in the giant barnacle, Balanus nubilus. By recording intracellularly from ganglion cells that respond to visual input, we have described convergence of the lateral and median visual pathways. 2. Each lateral eye contains three photoreceptor cells, two large and one small. Cobalt filling of single large lateral receptor axons demonstrated that they end in a restricted ovoid bush on the ipsilateral side of the ganglion in approximately the same region in which the median receptors arborize. 3. The lateral receptors have dark resting potentials and responses to light similar to those previously described for the receptors of the median eye. Like the median receptors, the lateral receptors conduct visual signals decrementally, although their axons may be twice as long (14-25 mm). 4. Passing current of either polarity into either of the large receptors produced no detectable voltage change in the other cell. Action potentials elicited in either cell by stimulating it in the presence of tetraethylammonium ion were not detected in the other cell. Light-induced membrane noise in one cell did not correlate with noise in the other. Thus, like the receptors of the median eye, the large receptors of the lateral eye are not electrically coupled. 5. By shadowing each ocellus individually, we have shown that the signals from the median and lateral photoreceptors converge at the level of the second-order cells described for the median pathway. Shadowing the median or a lateral eye gave rise to synergistic responses in second-, third-, and all higher order ganglion cells studied. No cells were found that were driven solely by the lateral eyes. Thus, the lateral and median visual pathways are highly convergent. 相似文献
59.
Coppin H Ribouchon MT Bausero P Pessac B Fontaine B Semana G Clanet M Roth MP;French Multiple Sclerosis Genetics Group 《Genes and immunity》2000,1(8):478-482
The myelin basic protein (MBP) gene is a candidate locus for susceptibility to multiple sclerosis. Several groups have tested a complex (TGGA)n repeat in the 5' region of this gene for association/linkage with multiple sclerosis, with divergent results. This region of tandem repetitive sequence has been subjected to complex rearrangements, and there is a possibility that alleles of the same size have different internal structures, which reduces the interest of this marker for linkage disequilibrium studies and may at least partly explain the conflicting results obtained so far. To overcome this problem, we isolated a new polymorphic (CA)n repeat within the Golli-MBP locus. The limited number of alleles identified makes this other marker suitable for transmission disequilibrium studies. We tested this marker for linkage with multiple sclerosis, using the transmission-disequilibrium test (TDT) on a sample of 196 nuclear families in which the genotypes of both parents could be unambiguously defined. We found no evidence of transmission disequilibrium between multiple sclerosis and any of the three alleles of this marker, even when the patients were subdivided according to their HLA-DRB1*1501 status. The present data thus provide no evidence for a contribution of the MBP gene to multiple sclerosis susceptibility in French patients. 相似文献
60.
Functional consequences of ROMK mutants linked to antenatal Bartter's syndrome and implications for treatment 总被引:4,自引:0,他引:4
The antenatal variant of Bartter's syndrome is an autosomal recessive
kidney disease characterized by polyhydramnios, premature delivery,
hypokalemic alkalosis and hypercalciuria. It is genetically heterogeneous,
having been linked recently to mutations in an ATP- sensitive, renal outer
medullary K+channel, ROMK, and earlier to mutations in the Na-K-2Cl
co-transporter, NKCC2. We characterized four of the mutations reported in
three heterozygous ROMK variants of antenatal Bartter's and found that each
expressed a distinct phenotype in Sf9 cells. One mutation expressed normal
function and appears to be an allelic polymorphism. The other three
mutations produced channels with significantly reduced K+fluxes. However,
the mechanisms in each case were different and reflected abnormalities in
phosphorylation, proteolytic processing or protein trafficking. The
different mechanisms may be important in the design of appropriate therapy
for patients with this disease.
相似文献