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Results for “Phenotypic variability”

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PubMed1982

[Phenotypic variability of the causative agent of pseudotuberculosis and its reflection in the immune response].

The avirulent rough form of Y. pseudotuberculosis has been shown to be a weak antigen, not stimulating antibody formation, quickly destroyed in phagocytes and possessing no immunogenic properties. The virulent bacteria in the smooth form multiply in macrophages and polymorphonuclear leukocytes, sharply suppress phagocytosis, stimulate the synthesis of IgM and IgG and possess low immunogenicity. The pseudorough form of Y. pseudotuberculosis quickly spreads in the organs and tissues, is destroyed by phagocytes, stimulates only the synthesis of IgM and produces a good protective effect.

Animals↗

PubMed2003

Phenotypic variability of aprataxin gene mutations.

The clinical and genetic features of three non-Portuguese and non-Japanese patients with aprataxin gene mutations are reported. Patient 1 came from Italy and presented with typical ataxia with ocular motor apraxia (OMA). She was homozygous for the W279X nonsense mutation, which is associated with the Portuguese founding haplotype. Patients 2 and 3 were French siblings and did not present with either OMA or hypoalbuminemia. They were compound heterozygous for the nonsense W279X mutation and a missense K197Q mutation.

Adult↗

PubMed1984

Phenotypic variability in Townes-Brocks syndrome.

This is a report on a child with sensorineural deafness, imperforate anus with rectovaginal fistula, hypoplastic thumb, and congenital heart defect. This pattern of congenital anomalies is similar to that described in patients with the Townes-Brocks syndrome, although the present patient has characteristics that have not been reported previously in this syndrome. It is proposed that the clinical spectrum of the Townes-Brocks syndrome must be extended to include congenital heart defect, auricular changes differing from those previously described, and anomalies of other internal organs. The syndrome is an autosomal dominant trait. The present case may represent a de novo mutation.

Abnormalities, Multiple↗

PubMed1992

The role of hereditary factors in phenotypic variability of hormone levels in the population genetically adapted to circumpolar environment.

The variability of the plasma cortisol, T3, T4, TSH and estradiol levels were studied in the North Khanty population genetically adapted to the extreme conditions of the North. The relationships between genetic markers and hormone concentrations were also studied. Negative linear correlations of T3 and T4 levels with age were obtained. Cortisol, estradiol and T3 levels showed nonlinear age dependency. T4 concentrations were significantly lower in August than in February and November. The highest heritability estimate was shown for estradiol levels (44%).

Acclimatization↗

PubMed1991

The role of hereditary factors in phenotypic variability of hormone levels in a population genetically adapted to the circumpolar environment.

The variability of plasma cortisol, T3, T4, TSH, and estradiol levels was studied in the North Khanty population genetically adapted to the extreme conditions of the North. Negative linear correlations of T3 and T4 levels with age were obtained. Cortisol, estradiol, and T3 levels showed nonlinear age dependency. T4 concentrations were significantly lower in August than February and November. The highest heritability estimate was shown for estradiol levels (44%). The relationships between genetic markers and hormone concentrations were studied.

Adult↗

PubMed1988

Phenotypic variability and heterozygosity at an esterase locus in the mosquito Aedes aegypti.

Populations of the yellow fever mosquito, Aedes aegypti L. are polymorphic for esterase alleles. This could be because the alleles are neutral or because selection protects the polymorphism, as had been concluded from a study of allele frequencies. A test has been carried out to look for possible associations of esterase heterozygosity with speed of development, body size and spine number symmetry in two spine rows. Heterozygotes were found to be larger and slower growing than homozygotes, but there was no difference in degree of asymmetry. There were fewer heterozygotes and a greater deficiency compared with expectation in insects reared at higher temperatures. It is concluded that different genotypes do differ in fitness.

Aedes↗

PubMedDate not supplied

[Phenotypic variability of a recombinant luminescent strain of Escherichia coli in water microcosms].

The behavior of Escherichia coli Z905, carrying a recombinant plasmid pPHL7 with genes determining ampicillin resistance and bacterial luminescence, and the efficiency of expression of cloned genes were studied after introduction of the strain into model aqueous ecosystems with different trophic chain lengths. The E. coli Z905 variants isolated from ecosystems after different periods of time were found to vary in their resistance to ampicillin (from 50 to 0.05 micrograms/ml) and in the intensity of bioluminescence. An increase in the concentration of the selective factor (ampicillin) or in the extent of the aqueous microcosm blooming restored the expression of the recombinant plasmid genes in some clones.

Ampicillin Resistance↗

PubMed2003

Leaf-level phenotypic variability and plasticity of invasive Rhododendron ponticum and non-invasive Ilex aquifolium co-occurring at two contrasting European sites.

To understand the role of leaf-level plasticity and variability in species invasiveness, foliar characteristics were studied in relation to seasonal average integrated quantum flux density (Qint) in the understorey evergreen species Rhododendron ponticum and Ilex aquifolium at two sites. A native relict population of R. ponticum was sampled in southern Spain (Mediterranean climate), while an invasive alien population was investigated in Belgium (temperate maritime climate). Ilex aquifolium was native at both sites. Both species exhibited a significant plastic response to Qint in leaf dry mass per unit area, thickness, photosynthetic potentials, and chlorophyll contents at the two sites. However, R. ponticum exhibited a higher photosynthetic nitrogen use efficiency and larger investment of nitrogen in chlorophyll than I. aquifolium. Since leaf nitrogen (N) contents per unit dry mass were lower in R. ponticum, this species formed a larger foliar area with equal photosynthetic potential and light-harvesting efficiency compared with I. aquifolium. The foliage of R. ponticum was mechanically more resistant with larger density in the Belgian site than in the Spanish site. Mean leaf-level phenotypic plasticity was larger in the Belgian population of R. ponticum than in the Spanish population of this species and the two populations of I. aquifolium. We suggest that large fractional investments of foliar N in photosynthetic function coupled with a relatively large mean, leaf-level phenotypic plasticity may provide the primary explanation for the invasive nature and superior performance of R. ponticum at the Belgian site. With alleviation of water limitations from Mediterranean to temperate maritime climates, the invasiveness of R. ponticum may also be enhanced by the increased foliage mechanical resistance observed in the alien populations.

Journal Article↗

PubMed1994

Cuticular hydrocarbon composition, phenotypic variability, and geographic relationships in allopatric populations of Amblyomma variegatum (Acari: Ixodidae) from Africa and the Caribbean.

Gas chromatography of cuticular hydrocarbons is used to determine the degree of genetic similarity and heterozygosity among 20 populations of Amblyomma variegatum (F.) collected from Africa and the Caribbean. Twenty-one compounds were detected in at least 90% of the specimens studied; another 57 hydrocarbons were detected in a variable number of specimens, ranging from 50 to 90% of all ticks extracted. Visual inspection of chromatograms revealed prominent differences in the relative abundance of hydrocarbons among the populations. Average heterozygosity was unexpectedly high (41.61%), whereas the average genetic identity among all populations was 0.8397. Principal components analysis for the relative amounts of several compounds did not provide adequate separation of populations according to geographical origin. Our data suggested that A. variegatum ticks are rapidly evolving and, while using several separate pathways, are sharing an undifferentiated genetic pool and retaining features that are typical for each population cluster.

Africa↗

PubMed1999

Basis of phenotypic variability in sporadic Creutzfeldt-Jakob disease.

OBJECTIVE: To determine the correlation of clinical and pathologic features with prion protein (PrP) gene polymorphism at codon 129 and with biochemical characteristics of the protease-resistant PrP (PrPres) in sporadic Creutzfeldt-Jakob disease (CJD). METHODS: Clinical data acquisition, determination of the codon 129 genotype of the PrP gene, brain pathologic study, and immunoblot analysis of crude brain extracts were carried out in 14 patients. RESULTS: The first group of 10 subjects showed the classic clinical triad, with dementia, myoclonus, and periodic sharp waves on EEG. None of the subjects had amyloid plaques, but PrP immunoreactivity was of diffuse synaptic type in the cerebellar cortex. All subjects were methionine-methionine at codon 129 and the PrPres had a biochemical profile of type 1 (unglycosylated band of 21.5 kD). A second group of three patients showed cerebellar ataxia and later dementia. Periodic sharp waves on EEG were absent. PrP amyloid plaques predominated in the cerebellar cortex, along with diffuse PrP immunoreactivity. These subjects were valine-valine at codon 129 and had a type 2 PrPres (unglycosylated band of 19.4 kD). In the last patient cerebellar ataxia and dementia appeared simultaneously. Many Kuru-type plaques were present in the cerebellar cortex; many PrP amyloid plaques were present in the basal ganglia. This patient was methionine-valine at codon 129 and the PrPres was of type 1. CONCLUSIONS: The codon 129 genotype is only one of the factors determining CJD phenotype, and the biochemical pattern of PrP has no direct correlation with this phenotype.

Aged↗

PubMed2004

Familial PAX8 small deletion (c.989_992delACCC) associated with extreme phenotype variability.

The PAX8 gene, mapped on 2q12-q14, encodes for a transcription factor involved in thyroid cell proliferation and differentiation. Five mutations in PAX8 have been so far described in both sporadic and rare familial forms of thyroid dysgenesis with proposed autosomal dominant inheritance, all associated with thyroid hypoplasia and/or dysfunction. Fifty-four subjects with congenital hypothyroidism detected during neonatal screening and associated with an ultrasound or scintiscan picture of thyroid dysgenesis were investigated for PAX8 mutations. The entire PAX8 coding region with exon-intron boundaries was amplified from genomic DNA, and a mutational screening was performed by denaturing HPLC followed by direct sequencing when denaturing HPLC elution abnormalities appeared. A new heterozygous deletion (c.989_992delACCC) in exon 7 causing a frameshift with premature stop codon after codon 277 was identified in a subject with thyroid hypoplasia. This mutation is the only one so far identified that lies outside the paired domain. The predicted mutant protein completely lacks the C-terminal region but contains the paired box, octapeptide, and homeodomain. It retains the ability to bind a paired-domain sequence in vitro but is transcriptionally inactive. These results provide evidence that the C-terminal region is essential for transcriptional activity. The new mutation has been inherited from the completely euthyroid mother. It was also present in a brother with slightly elevated TSH only. Thus, it is associated with thyroid dysgenesis in the proband and both euthyroidism and compensated hypothyroidism in her family. This suggests that other factors/genes may modulate phenotypic expression.

Amino Acid Sequence↗

PubMed1994

Platelet-mediated transformation of mtDNA-less human cells: analysis of phenotypic variability among clones from normal individuals--and complementation behavior of the tRNALys mutation causing myoclonic epilepsy and ragged red fibers.

In the present work, we demonstrate the possibility of using human blood platelets as mitochondrial donors for the repopulation of mtDNA-less (rho 0) cells. The noninvasive nature of platelet isolation, combined with the prolonged viability of platelet mitochondria and the simplicity and efficiency of the mitochondria-transfer procedure, has substantially increased the applicability of the rho 0 cell transformation approach for mitochondrial genetic analysis and for the study of mtDNA-linked diseases. This approach has been applied to platelets from several normal human individuals and one individual affected by the myoclonic-epilepsy-and-ragged-red-fibers (MERRF) encephalomyopathy. A certain variability in respiratory capacity was observed among the platelet-derived rho 0 cell transformants from a given normal subject, and it was shown to be unrelated to their mtDNA content. The results of sequential transfer of mitochondria from selected transformants into a rho 0 cell line different from the first rho 0 acceptor strongly suggest that this variability reflected, at least in part, differences in nuclear gene content and/or activity among the original recipient cells. A much greater variability in respiratory capacity was observed among the transformants derived from the MERRF patient and was found to be related to the presence and amount of the mitochondrial tRNALys mutation associated with the MERRF syndrome. An analysis of the relationship between proportion of mtDNA carrying the MERRF mutation and degree of respiratory activity in various transformants derived from the MERRF patient revealed an unusual complementation behavior of the tRNALys mutation, possibly reflecting the distribution of mutant mtDNA among the platelet mitochondria.

Adult↗

PubMed1986

Invasion and coexistence of two phenotypically variable species.

The effect of ecological polymorphism on the coexistence of species has not previously been studied. Using a model of competitive interactions within and among species I investigate invasion of both monomorphic and polymorphic species. Three comparisons are considered which place previous work in a broader context and extend it to cover the situations characterized by polymorphism. First, I examine invasion of a monomorphic species into the range of another monomorphic species. This is done in a manner which allows for generalization to the following more complex cases. Second, I examine invasion of a monomorphic species into the range of a polymorphic species. Finally, I examine invasion and coexistence of a polymorphic species in the range of another polymorphic species. This sequence of comparisons produces some simple generalizations concerning invasion and coexistence of species in a variety of ecological situations. Furthermore, it emphasizes polymorphism as a potentially important factor in shaping ecological communities.

Animals↗

PubMed1993

Phenotypic variability in autosomal dominant cerebellar ataxia type I is unrelated to genetic heterogeneity.

Families with autosomal dominant cerebellar ataxia (ADCA), a heterogeneous group of diseases, were investigated prior to and during genetic linkage analysis. We report here on the clinical features of 122 affected individuals from 36 unrelated families with ADCA type I, the most common type. Our results indicate an anticipation expressed in a mean 9.4 year earlier age at onset and more rapid clinical progression in successive generations. There was no imprinting, since age at onset, disease duration and severity of the disease were independent of parental transmission. Progressive cerebellar ataxia was variably associated with signs such as ophthalmoplegia, dysphagia, sphincter disturbances, briskness or loss of tendon reflexes, decreased vibration sense and amyotrophy, a variability correlated with disease duration. Linkage analysis of 10 informative families with microsatellite markers, located on the short arm of the chromosome 6, allowed the identification of four families showing positive linkage to the SCA1 (spinal cerebellar ataxia 1) locus and six non-SCA1 families for whom linkage to this locus was excluded. This reflects non-allelic genetic heterogeneity. Thus, the analysis of clinical signs associated with cerebellar ataxia in SCA1 versus non-SCA1 kindreds did not distinguish between the two groups. The clinical picture of ADCA type I did not reflect the genetic heterogeneity of the disease.

Adolescent↗

PubMed1989

[Phenotype variability in Steinert's myotonic dystrophy].

Myotonic dystrophy, best known in the French literature as Steinert disease, is a dominantly inherited disorder. When the gene is fully expressed, it shows a characteristic clinical picture. Myopathy and myotonia are the main features, but this is a systemic disease which may involve many other organs such as the central nervous system, eyes, bones, endocrine system, etc. With the complete picture, physical and behavioral features make the diagnosis easy, only to be confirmed by neurological and ophthalmologic examination and/or electromyography. This work reviews the main clinical signs seen in the classical form of the disease. We also want to stress the variability of that picture. Finally, we describe a new dysmorphic sign in myotonic dystrophy: large prominent cupped auricles. Although not recognized, prominauris has been illustrated in a number of publications on myotonic dystrophy. Three of our adult male patients presenting the congenital form of the disease at birth have been investigated to rule out concomitant fragile-X syndrome. Both syndromes include mental retardation and dysmorphic ears. Our patients show the usual testicular atrophy, whereas the fragile-X syndrome includes testicular hypertrophy. Cytogenetic studies were normal. Old clinical description and new physical signs may lack prestige in the perspective of recent molecular biological breakthroughs, but to recognize the disease and help patients live with it will always be the role of practitioners.

Adult↗

PubMed2000

Gilbert's syndrome accounts for the phenotypic variability of congenital dyserythropoietic anemia type II (CDA-II).

The molecular basis for the considerable variation of serum bilirubin levels and the incidence of gallstone formation in patients with congenital dyserythropoietic anemia (CDA) type II are unknown. We show that the combined effect of an increased bilirubin load caused by dyserythropoiesis in CDA II and decreased bilirubin conjugation caused by reduced expression of uridine diphosphate glucuronosyl transferase (UGT1A) would increase the risk of hyperbilirubinemia (P <.005) and gallstone formation (chi(2): P <. 001). The rate of gallstone formation in patients with CDA II is 4. 75-fold the rate of patients without Gilbert's syndrome, and gallstone diagnosis occurs at a younger age (P < 0.01). These findings should be considered during the follow-up of patients with CDA II.

Adolescent↗

PubMed1998

Phenotype variability of the dominant beta-thalassemia induced in four Dutch families by the rare cd121 (G-->T) mutation.

Eight patients who were carriers of beta-thalassemia induced by the cd121 (G-->T) mutation are described in four nonrelated Dutch families. This mutant, which is considered rare and inherited in a dominant manner, is expressed in a different way among each of the four families and even among carriers of the same family. The symptoms vary from an hemolytic anemia of intermediate gravity with hepatosplenomegaly, inclusion bodies and erythroblastosis, to a mild anemia with minor hematological abnormalities. We report the analytical procedures used for the detection of the mutant, the hematological and clinical data of the four families and discuss the variable physiopathology of this molecular defect. We also compare the variation in fetal hemoglobin expression in relation to the haplotypes of the beta-gene cluster and to the different hematological conditions. The presence of this rare mutant in four nonrelated Dutch families could derive from a single mutation or from multiple events. The existence of the four mutations in three different haplotypes suggests the occurrence of at least two independent events. The presence of five abnormal hemoglobins and the beta-thalassemia defect on different haplotypes at cd121 also suggests a relatively increased rate of mutations at this particular site.

Adult↗

PubMed2002

A novel mutation in PIT-1: phenotypic variability in familial combined pituitary hormone deficiencies.

Mutations in PIT-1 have been described in several cases of familial combined pituitary hormone deficiencies. This study describes a novel PIT-1 mutation that was found in two siblings of a highly consanguineous family of Israeli-Arab origin. The missense mutation (G688A) causes a lysine (K) to glutamic acid (E) substitution at codon 230. This codon resides in the first helix of the POU-homeodomain, which is directly involved in DNA binding. This amino acid is conserved in most homeodomain proteins, suggesting that the substitution disrupts the DNA-binding activity of the mutant protein. Two main observations are described: 1. The clinical presentation of the mutation involves intrauterine growth retardation. 2. One sibling had full deficency of growth hormone and thyroid stimulating hormone, whereas the other had only growth hormone deficiency. This is, to the best of our knowledge, a unique expression of a novel PIT-1 mutation.

DNA↗