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PubMed2001

Estimation of the genetic parameters of meat characteristics and of their genetic correlations with growth and body composition in an experimental broiler line.

Genetic parameters of breast meat characteristics [pH 15 min postmortem (pH15min), ultimate pH (pHu), CIELAB color parameters (L*, lightness; a*, redness; b*, yellowness) and drip loss (DL)] as well as their genetic correlations with BW and body composition [breast yield (BRY) and abdominal fat percentage (AFP)] were estimated in an experimental meat-type chicken line. Heritability of the pH of meat was high for pHu (0.35 +/- 0.03) and even more so for pH15min (0.49 +/- 0.01). Color parameters appeared to be the most heritable traits, with heritability values ranging from 0.50 to 0.57. Drip loss heritability was estimated at 0.39 +/- 0.04. The rate and the extent of pH decline seemed to be controlled by different genes, as shown by the extremely low estimated genetic correlation (0.02 +/- 0.04) between pH15min and pHu. The ultimate pH of the meat was genetically very strongly related to its lightness (-0.91 +/- 0.02) and water-holding capacity (-0.83 +/- 0.04). These results suggest that selection for pHu could be exploited to prevent increased incidence of pale and exudative meat. The pH15min was poorly correlated with the other meat characteristics, with estimated correlations of 0.13, -0.23, 0.05, and -0.29 for L*, a*, b*, and DL, respectively. These results may be explained by the fact that, in our experimental conditions, pH15min remained high (between 6.01 and 6.75). Body weight and BRY exhibited poor genetic correlations (ranging from -0.06 to 0.13) with the pH of the meat at 15 min and 24 h postmortem. Both of the former traits were moderately negatively correlated with a* and b* values. A significant negative genetic correlation was observed between abdominal fatness and pHu. These results do not support the idea that selection for growth and breast development has a detrimental effect on breast meat quality even if, in the long term, the color intensity could be decreased.

Animals↗

PubMedDate not supplied

Genetic and environmental influences in adolescent peer socialization: evidence from two genetically sensitive designs.

Harris argues that peer relationships are the chief determinants of personality development. Harris's thesis makes the behavioral genetic investigation of peer groups particularly timely. The present study examined genetic and environmental contribution to self-reported peer-group characteristics in two samples of adolescent siblings: 180 adoptive and nonadoptive sibling pairs from the Colorado Adoption Project, and 386 sibling pairs from the Nonshared Environment and Adolescent Development Study. Substantial genetic influence emerged for college orientation, with the remaining variance accounted for by nonshared environment. For delinquency, however, the majority of the variance was explained by nonshared environment. Although genetic influence was implicated for peer popularity in twin analyses, genetic factors were not important in explaining individual differences in nontwin siblings. These results suggest that although some dimensions of peers are somewhat mediated by genetic factors, nonshared environmental influence is substantial.

Adolescent↗

PubMed2003

Genetic variation in male effects on female reproduction and the genetic covariance between the sexes.

Males of many insect species increase the fecundity and/or egg size of their mates through the amount or composition of their nuptial gifts or ejaculate. The genetic bases of such male effects on fecundity or egg size are generally unknown, and thus their ability to evolve remains speculative. Likewise, the genetic relationship between male and female investment into reproduction in dioecious species, which is expected to be positive if effects on fecundity are controlled by at least some of the same genes in males and females, is also unknown. Males of the seed beetle Stator limbatus contribute large ejaculates to females during mating, and the amount of donated ejaculate is positively correlated with male body mass. Females mated to large males lay more eggs in their lifetime than females mated to small males. We describe an experiment in which we quantify genetic variation in the number of eggs sired by males (mated to a single female) and found that a significant proportion of the phenotypic variance in the number of eggs sired by males was explained by their genotype. Additionally, the number of eggs sired by a male was highly positively genetically correlated with his body mass. The between-sex genetic correlation, that is, the genetic correlation between the number of eggs sired by males and the number of eggs laid by females, was highly positive when eggs were laid on Acacia greggii seeds. This indicates that males that sire many eggs have sisters that lay many eggs. Thus, some of the genes that control male ejaculate size (or some other fecundity-enhancing factor) when expressed in males appear to control fecundity when expressed in females. We found no significant interaction between male and female genotype on fecundity.

Animals↗

PubMed2004

Genetic structuring of Patagonian toothfish populations in the Southwest Atlantic Ocean: the effect of the Antarctic Polar Front and deep-water troughs as barriers to genetic exchange.

The environmental and/or life history factors affecting genetic exchange in marine species with potential for high dispersal are of great interest, not only from an evolutionary standpoint but also with regard to effective management. Previous genetic studies have demonstrated substantial differentiation among populations of the Patagonian toothfish around the Southern Ocean, indicating breakdown of gene flow across large distances between inhabited shelf areas. The present study examined genetic structuring through analysis of microsatellite loci and restriction fragment length polymorphism (RFLP) of the mitochondrial ND2 gene and control region of the toothfish population in the SW Atlantic, allowing examination of the relative effects of the Antarctic Polar Front (APF), deep-water troughs and distance between sites. Mitochondrial DNA (mtDNA) data indicated a sharp genetic division between the Patagonian Shelf/North Scotia Ridge and the Shag Rocks/South Georgia samples, whereas microsatellite data showed much less distinct structuring and an intermediate position of the North Scotia Ridge samples. We suggest these data indicate that the APF, as a barrier to larval dispersal, is the major inhibitor of genetic exchange between toothfish populations, with deep-water troughs and distance between sites contributing to genetic differentiation by inhibiting migration of relatively sedentary adults. We also suggest that differences between mtDNA and nuclear DNA population patterns may reflect either genome population size effects or (putative) male-biased dispersal.

Animals↗

PubMed2006

Extremely low effective population sizes, genetic structuring and reduced genetic diversity in a threatened bumblebee species, Bombus sylvarum (Hymenoptera: Apidae).

Habitat fragmentation may severely affect survival of social insect populations as the number of nests per population, not the number of individuals, represents population size, hence they may be particularly prone to loss of genetic diversity. Erosion of genetic diversity may be particularly significant among social Hymenoptera such as bumblebees (Bombus spp.), as this group may be susceptible to diploid male production, a suggested direct cost of inbreeding. Here, for the first time, we assess genetic diversity and population structuring of a threatened bumblebee species (Bombus sylvarum) which exists in highly fragmented habitat (rather than oceanic) islands. Effective population sizes, estimated from identified sisterhoods, were very low (range 21-72) suggesting that isolated populations will be vulnerable to loss of genetic variation through drift. Evidence of significant genetic structuring between populations (theta = 0.084) was found, but evidence of a bottleneck was detected in only one population. Comparison across highly fragmented UK populations and a continental population (where this species is more widespread) revealed significant differences in allelic richness attributable to a high degree of genetic diversity in the continental population. While not directly related to population size, this is perhaps explained by the high degree of isolation between UK populations relative to continental populations. We suggest that populations now existing on isolated habitat islands were probably linked by stepping-stone populations prior to recent habitat loss.

Animals↗

PubMed2006

France: genetics education for non-genetics health care providers.

OBJECTIVE: This paper explores the treatment of medical genetics in undergraduate medical education, specialists' training and continuing medical education (CME) for general practitioners, specialists, nurses and midwives. METHODS: We conducted a qualitative survey of websites, published or unpublished documents, telephone interviews and mailed questionnaires. RESULTS: Genetics is a medical specialty in France, and the small number of university professors in genetics are in charge of the genetic component of medical training of all future practitioners. The study was complicated by the ongoing waves of reforms in the French health and educational systems and by the autonomy of the faculties. Specialist training and CME in genetics is heterogeneous and not organised as a priority. CONCLUSIONS: Specialist education and CME in genetics of non-geneticist health care providers needs to be adapted to the fast ongoing developments of this field of knowledge.

Education, Medical, Continuing↗

PubMed1994

Pathology of atheromatous lesions in inbred and genetically engineered mice. Genetic determination of arterial calcification.

We report comprehensive pathological studies of atheromatous lesions in various inbred mouse strains fed a high-fat, high-cholesterol diet and in two genetically engineered strains that develop spontaneous lesions on a low-fat chow diet. Coronary and aortic lesions were studied with respect to anatomic locations, lesion severity, calcification, and lipofuscin deposition. Surprisingly, the genetic determinants for coronary fatty lesion formation differed in part from those for aortic lesion development. This suggests the existence of genetic factors acting locally as well as systematically in lesion development. We used immunohistochemical analyses to determine the cellular and molecular compositions of the lesions. The aortic lesions contained monocyte/macrophages, lipid, apolipoprotein B, serum amyloid A proteins, and immunoglobulin M and showed expression of vascular cell adhesion molecule-1 and tumor necrosis factor-alpha, all absent in normal arteries. In certain strains, advanced lesions developed in which smooth muscle cells were commonly observed. The lesions in mice targeted for a null mutation in the apolipoprotein E gene were much larger, more widely dispersed, and more fibrous, cellular, and calcified in nature than the lesions in laboratory inbred strains. When apolipoprotein A-II transgenic mice were maintained on a low-fat chow diet, the lesions in these mice were relatively small and located in the very proximal regions of the aorta. There were clear differences in the occurrence of arterial wall calcification among genetically distinct inbred mouse strains, indicating for the first time a genetic component in this clinically significant trait. Analysis of a genetic cross indicated a complex pattern of calcification inheritance with incomplete penetrance.

Animals↗

PubMed2001

Genetic counselling for schizophrenia in the era of molecular genetics.

OBJECTIVE: To review the role of genetic counselling for individuals with psychiatric illnesses. METHOD: Using schizophrenia as an example and including updated information about a genetic subtype (22q deletion syndrome), we discuss the value of the genetic counselling process in psychiatry, with support from the literature and our clinical experience. RESULTS: Genetic counselling, the process through which knowledge about the genetics of illnesses is shared, provides information on the inheritance of illnesses and their recurrence risks; addresses the concerns of patients, their families, and their health care providers; and supports patients and their families dealing with these illnesses. For comprehensive medical management, this service should be available to all individuals with schizophrenia and their families. CONCLUSIONS: New findings in the genetics of psychiatric illness may have important clinical implications for patients and their families.

Chromosome Deletion↗

PubMedDate not supplied

Genetic variability of six French meat sheep breeds in relation to their genetic management.

Some demographic parameters, the genetic structure and the evolution of the genetic variability of six French meat sheep breeds were analysed in relation with their management. Four of these breeds are submitted to more or less intense selection: the Berrichon du Cher (BCH), Blanc du Massif Central (BMC), Charollais (CHA) and Limousin (LIM); the other two breeds are under conservation: the Roussin de La Hague (RLH) and Solognot (SOL). Genealogical data of the recorded animals born from 1970 to 2000 and of their known ancestors were used. The most balanced contributions of the different flocks to the sire-daughter path was found in the SOL. In the BCH, a single flock provided 43% of the sire-AI sire path, whereas the contributions of the flocks were more balanced in the BMC and LIM (the only other breeds where AI is used to a substantial amount). The distribution of the expected genetic contribution of the founder animals was found to be unbalanced, especially in the BCH and LIM. The effective numbers of ancestors (founders or not) for the ewes born from 1996 to 2000 were equal to 35 (BCH), 144 (BMC), 112 (CHA), 69 (LIM), 40 (RLH) and 49 (SOL). Inbreeding was not analysed in the BMC, due to incomplete pedigree information. From 1980 on, the rates of inbreeding, in percentage points per year, were +0.112 (BCH), +0.045 (CHA), +0.036 (LIM), +0.098 (RLH) and +0.062 (SOL). The implications of the observed trends on genetic variability are discussed in relation to the genetic management of each breed. The need for a larger selection basis in the BCH, the efficiency of the rules applied in the SOL to preserve the genetic variability and the need for a more collective organisation in the CHA and RLH are outlined.

Animals↗

PubMedDate not supplied

Genetic management of infectious diseases: a heterogeneous epidemio-genetic model illustrated with S. aureus mastitis.

Given that individuals are genetically heterogeneous in their degree of resistance to infection, a model is proposed to formulate appropriate choices that will limit the spread of an infectious disease. The model is illustrated with data on S. aureus mastitis and is based on parameters characterizing the spread of the disease (contact rate, probability of infection after contact, and rate of recovery after infection), the demography (replacement and culling rates) and the genetic composition (degree of relationship and heritability of the disease trait) of the animal population. To decrease infection pressure, it is possible to apply non-genetic procedures that increase the culling (e.g., culling of chronically infected cows) and recovery (e.g., antibiotic therapy) rates of infected cows. But the contribution of the paper is to show that genetic management of infectious disease is also theoretically possible as a control measure complementary to non-genetic actions. Indeed, the probability for an uninfected individual to become infected after contact with an infected one is partially related to their degree of kinship: the more closely they are related, the more likely they are to share identical genes like those associated to the non-resistance to infection. Different prospective genetic management procedures are proposed to decrease the contact rate between infected and uninfected relatives and keep the number of secondary cases generated by one infected animal below 1.

Alleles↗

PubMed1994

Genetic influences on type I collagen synthesis and degradation: further evidence for genetic regulation of bone turnover.

Circulating osteocalcin, a marker of bone formation, is under strong genetic influence, and this effect is related to the genetic influence on bone density. To examine genetic influences on bone turnover further, other markers of bone formation (serum carboxyterminal propeptide of type I procollagen, PICP), bone resorption (serum pyridinoline cross-linked carboxyterminal telopeptide of type I collagen, ICTP), and nonosseous connective tissue synthesis (serum aminoterminal propeptide of type III procollagen, PIIINP) were studied in 82 female twin pairs: 42 monozygotic (MZ) and 40 dizygotic (DZ) twin pairs (mean age, MZ; 48.4 yr; DZ; 45.6 yr). The intraclass correlation coefficients of MZ twin pairs, rMZ, for serum PICP (0.78) and serum ICTP (0.68) were significantly greater than the corresponding rDZ (0.31 and 0.36, respectively), but a genetic effect on serum PIIINP was not demonstrable. Within DZ twin pair differences in serum PICP predicted differences in lumbar spine bone density (r = -0.37); higher serum PICP levels indicating the twin with the lower lumbar spine bone density. Also within pair differences in serum ICTP and PICP predicted differences in bone density at the lumbar spine independent of serum osteocalcin. These data indicate that both synthesis and degradation of type I collagen are genetically determined and that this phenomenon is related to the genetic regulation of bone density.

Analysis of Variance↗

PubMed2003

Does advertisement call variation coincide with genetic variation in the genetically diverse frog taxon currently known as Leptodactylus fuscus (Amphibia: Leptodactylidae)?

The frog Leptodactylus fuscus is found throughout much of South America in open and disturbed habitats. Previous study of genetic differentiation in L. fuscus demonstrated that there was lack of genetic exchange among population units consistent with multiple species, rather than a single species. We examine advertisement vocalizations of L. fuscus to determine whether call variation coincides with genetic differentiation. Calls were analyzed for 32 individual frogs from 25 localities throughout the distributional range of L. fuscus. Although there is variation in calls among geographic samples, call variation is not concordant with genetic variation or geographic distance and the call variation observed is less than that typically found among other closely related species of Leptodactylus. This study is an example of the rare pattern of strong genetic differentiation unaccompanied by salient differences in advertisement calls. The relative infrequency of this pattern as currently understood may only reflect the lack of detailed analyses of genetic and acoustic differentiation within population systems currently understood as single species with substantial geographic distributions.

Animals↗

PubMed2000

[The importance of genetics in the public health care system: report on the closing down of a genetics division in São Paulo, Brazil].

The availability of genetics services in hospitals should be an issue of public concern. Having genetics services helps shorten the time spent in making diagnoses and reduces the average number of inpatient days; it also helps accelerate the choice of adequate treatments, prevents or minimizes sequelae, and, ultimately, reduces costs. The objective of the present study was to describe the closing down in 1996 of the genetics division at the Menino Jesus Children's Hospital, a pediatric institution located in the city of São Paulo, SP, Brazil. A retrospective analysis was carried out of the work performed by this division between 1992 and 1996, with an emphasis on the detection of chromosomal abnormalities. Of all cases assessed during the study period, 571 were entered into a database. Some kind of chromosomal abnormality was observed in 20% of the 350 karyotypes performed. The existence of genetics services in hospitals helps minimize the appearance of clinical symptoms in carriers of genetic abnormalities, improves the quality of life of these patients, and enables them to receive information regarding risk of recurrence, while preventing the waste of resources that results from tests that are costly and unnecessary. Such benefits amply justify the investment in setting up genetics services of the type described here.

Brazil↗

PubMed2000

New insights into genetic aspects of Alzheimer's disease. Does genetic information make a difference in clinical practice?

Genetic testing sometimes offers definitive information for patients who have a family history of early-onset Alzheimer's disease that occurs before age 50 in a Mendelian pattern. However, for patients who are already symptomatic, especially those with sufficient symptoms to warrant a clinical diagnosis of Alzheimer's disease, genetic testing may not contribute a great deal of information beyond that already available from the clinical and family history. For prediction of disease onset, genetic testing can sometimes give a clear picture of disease risk, but each patient must carefully weigh the risks and benefits of having that information. For early-onset Alzheimer's disease occurring beyond age 50 or without a clear Mendelian pattern, genetic testing is unlikely to be informative. In patients who have a family history of late-onset Alzheimer's disease, while APOE's contribution to increased risk is indisputable, its potential use as a genetic test is very limited. Testing may be helpful as an adjunct to clinical diagnosis but does not obviate the need for a full workup for treatable causes. Thus, the benefit of testing may be marginal. No consensus has been reached as to the value of genetic testing for early detection of late-onset disease, but APOE testing might become important in the future if it helps to define the need for intervention or to select an optimal intervention. There is a broad consensus that APOE testing lacks sufficient predictive value to be suitable for predictive testing in asymptomatic persons.

Adult↗

PubMed1990

Innovations in human genetics education. Incorporation of genetics into a problem-based medical school curriculum.

There has been recent interest in the development of problem-based human genetics curricula in U.S. medical schools. The College of Human Medicine at Michigan State University has had a problem-based curriculum since 1974. The vertical integration of genetics within the problem-based curriculum, called "Track II," has recently been revised. On first inspection, the curriculum appeared to lack a significant genetics component; however, on further analysis it was found that many genetics concepts were covered in the biochemistry, microbiology, pathology, and clinical science components. Both basic science concepts and clinical applications of genetics are covered in the curriculum by providing appropriate references for basic concepts and including inherited conditions within the differential diagnosis in the cases studied. Evaluations consist of a multiple-choice content exam and a modified essay exam based on a clinical case, allowing evaluation of both basic concepts and problem-solving ability. This curriculum prepares students to use genetics in a clinical context in their future careers.

Curriculum↗

PubMed1986

[Genetic analysis of the structure of predisposition to diabetes mellitus. III. Genetic heterogeneity of diabetes mellitus with different ages of onset].

The results of genetical-epidemiological analysis of the three conventional forms of diabetes mellitus (DM) differentiated for age-at-onset are presented (the form I - from 0 to 29 y. the form II - from 30 to 59 y. the form III - 60 y. and older). The estimates of heritability of liability to the forms I, II and III of DM were 0.57, 0.70 and 0.65, respectively. It was shown that genetic components of the forms I and II are virtually different: genetic correlation between these forms was rA = 0.216 +/- 0.203, which is statistically insignificant. These data support the hypothesis assuming genetic independence of juvenile and adult forms of DM. On the other hand, the forms II and III were found to have an essential number of genes in common: genetic correlation was rA = 0.495 +/- 0.134, being significant at the 5% level. Thus, the forms II and III of DM are not to be considered as two genetically distinct diseases. The low recurrence risks of the form I for siblings (not more than 3.6%) allow to reject the hypothesis of simple monogenic inheritance of juvenile DM and to propose multifactorial nature of the disease.

Adolescent↗

PubMed1982

Population genetics in the State of Nuevo Leon, Mexico. V. Frequencies of ABO, Rh (D), MN blood groups and other genetic traits.

During the last years we have been studying the phenotype and gene frequencies of blood groups and other genetic traits in order to learn the genetic composition of the human population in the State of Nuevo Leon. We tried to assess the influence of the different ancestral contributions in the degree of genetic diversity within the state, and also to evaluate the frequencies of some genetic traits in groups of persons suffering from various diseases. It has been found that for most traits the frequencies are intermediate to those reported for Mexican native and Spanish populations. It appears that the populations that recently immigrated to the State are the ones that have received more genetic influence from the Mexican natives, and those that have lived in the state since the last century are the ones that have received more genetic contribution from the Spanish.

ABO Blood-Group System↗

PubMed1982

Lack of impact of undergraduate genetic courses on the teaching of medical genetics.

The impact of undergraduate genetic courses on the academic performance of first-year medical students in the medical genetics course at the University of Pittsburgh School of Medicine was evaluated over a period of 9 years. Comparisons were made between medical students who had taken a formal undergraduate course in genetics and those who had not. Little if any differences were found in the academic performance in the medical genetics course between these two groups of students. Perhaps the design of undergraduate courses in genetics should be re-evaluated to give more depth to the medical student's preparation for appreciating the significance of genetics in normal and abnormal human variation.

Education, Medical, Undergraduate↗