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PubMedDate not supplied

Multifactorial inheritance of white facial markings in the Arabian horse.

The hypothesis was tested that white facial markings in the Arabian horse show multifactorial inheritance. The hypothesis assumes that (1) alleles at different loci acting in a cumulative manner influence the variation in white facial markings, (2) the amount of whiteness is correlated with the number of genes, and (3) interacting nongenetic factors influence the variation. The study was based on computerized data obtained from the Arabian Horse Registry of America, Inc. The facial region was divided into five areas, and each horse was given a score according to the number of areas with a white marking. Twenty-two sire families were analyzed. Each sire family consisted of a sire, his foals, and the dams of those foals. The results of the investigation, including dam-foal and sire-foal regression analyses, were totally compatible with the hypothesis. A heritability study suggested that about two-thirds of the phenotypic variation in white facial markings among Arabian horses is attributable to genetic differences.

Animals↗
PubMedDate not supplied

Patchy fur (Paf), a semidominant X-linked gene associated with a high level of X-Y nondisjunction in male mice.

Several X-linked mutations that have associated sex chromosomal nondisjunction have been identified in the mouse. We describe a new semidominant X-linked mutation called patchy fur (Paf) that produces an abnormal coat. It maps to the distal end of the murine X chromosome very near the XY pseudoautosomal region. The degree of severity in affected mice is hemizygous males greater than homozygous females greater than heterozygous females. An unusual feature of Paf is that either the mutation itself or an inseparable chromosomal abnormality causes delayed disjunction of the X and Y chromosomes at meiotic metaphase I, which in turn results in approximately 19% XO progeny and slightly less than 1% XXY progeny from Paf/Y males. The effect occurs only in male carriers and thus must extend into the proximal end of the XY pairing region.

Animals↗
PubMedDate not supplied

Multifactorial inheritance of common white markings in the Arabian horse.

The results of a previous study were compatible with the hypothesis that common white facial markings in the Arabian horse have a multifactorial mode of inheritance. I expanded that study to (1) include the legs and therefore obtain insight into the heritability of common white markings in all peripheral regions (face and legs) of the Arabian horse and (2) investigate the influence of sex and the genotypes that produce the bay and chestnut phenotypes on the variation in common white markings. Both studies were based on computerized data obtained from the Arabian Horse Registry of America, Inc. Each leg of a horse was scored from 0 to 5 depending on the amount of whiteness present, and the four leg scores were added to obtain the total leg score for each horse. The facial region was divided into five areas, and each horse was given a score from 0 to 5 according to the number of areas with whiteness. Sire families were analyzed in which each sire family consisted of a sire, his foals, and the dams of those foals. There was a correlation between white facial scores and white leg scores, suggesting that both types of white markings are influenced by the same genetic mechanism. Sire-foal and dam-foal regression analyses were compatible with the hypothesis that common white leg markings also show multifactorial inheritance. Although the results support the model that additively acting genes (polygenes) influence the presence and extent of common white markings, the results also show that males are slightly more marked than are females and that chestnut horses are more heavily marked than are bay horses.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMedDate not supplied

The inheritance of the leopard complex of spotting patterns in horses.

The leopard complex of white spotting patterns in horses consists of the leopard, few-spot leopard, blanket, blanket with spots, varnish roan (or marble), snowflake, frosted, speckled, and mottled patterns. Horses with any of these patterns can produce the other patterns when mated to nonpatterned horses. Twenty-two horses of the Welsh Pony, Noriker, Appaloosa, and Pony of the Americas breeds produced 270 foals in a distribution consistent with a single dominant allele being responsible for the patterns. The symbol for this dominant allele, Lp, is retained from previous work on the leopard pattern. Heterozygotes are less extensively marked than are homozygotes, but the two classes overlap. The differences in the patterns are related to varying degrees of expression of this allele.

Alleles↗
PubMedDate not supplied

Common white facial markings in bay and chestnut Arabian horses and their hybrids.

Common white facial and leg markings have a multifactorial mode of inheritance in Equus caballus. Evidence for the complexity of the genetic component is the observation that chestnut (e/e) horses have more extensive white markings than do bay (E/-) horses. Computerized records obtained from the Arabian Horse Registry of America, Inc., were used to determine if heterozygous (E/e) bay horses have more extensive white facial markings than do homozygous (E/E) bay horses. Thirty-five sire families were analyzed. Each sire family consists of a sire, his foals, and the dams of those foals. The facial region was divided into five areas, and each horse was given a score from 0 to 5 according to the number of areas with whiteness. Since dams and foals with E/E genotypes cannot be identified in these sire families, mean facial scores were compared in dams and foals that were E/e and E/-. It was assumed that if a difference exists between E/e and E/E horses, the presence of E/E horses in the E/- group would reduce the mean of the E/- group. The results show that Arabian horses with the genotype E/e have more white markings than do horses with the genotype E/-, leading to the conclusion that horses with the genotypes e/e, E/e, and E/E vary as to the quantitative expression of white facial markings, with heterozygotes having an intermediate expression.

Animals↗
PubMedDate not supplied

Locally associated alleles of cat coat genes.

Published allele frequencies of coat genes from 204 cat (Felis catus) populations all over the world are studied by means of correlation and principal component analyses. Locally associated groups of alleles with correlated frequencies are revealed [the (0, d, I, W), (a, tb), and (S) allele groups]. The phenomenon must have resulted from the parallel action of local selection vectors on a worldwide scale. In particular, the (0, d, I, W)-group is formed by the vector of artificial selection. It is shown that principal component analysis facilitates revealing of such associated alleles connected by moderate correlation. This analysis also allows us to classify the populations by plotting them in two-dimensional space of two main components containing the most part of the total allele frequency variance.

Alleles↗
PubMedDate not supplied

Dominant inheritance of overo spotting in paint horses.

Analysis of selected studbook records of the American Paint Horse Association, consisting of 687 foals sired by 13 overo stallions from non-overo mares, supports the inheritance of overo spotting as an autosomal dominant gene. More than one gene may control patterns registered as overo. Additional studies are necessary to explain the sporadic occurrence of overo spotting from nonspotted quarter horse parents and to confirm the inheritance of overo spotting in other breeds.

Animals↗
PubMedDate not supplied

Influence of stochastic events on the phenotypic variation of common white leg markings in the Arabian horse: implications for various genetic disorders in humans.

One method of assessing the influence of stochastic events on phenotypic variation is to study morphological differences in paired limbs of the same individual. These limbs have identical genotypes and similar intra-uterine environments and are analogous to monozygotic twins. Common white leg markings have a multifactorial mode of inheritance in the Arabian horse. Asymmetry occurs frequently for these markings. Using computerized registration records obtained from the Arabian Horse Registry of America, Inc., the types of markings were quantified in the left foreleg and left hind leg of bay and chestnut horses when a specific marking occurred in (1) a paired right leg, (2) both right legs, and (3) both right legs and the other left leg. The variation in the markings in the left legs of these horses is evidence of the role of stochastic events during development. The relatively high frequency of a specific type of asymmetry, with one leg being completely pigmented, is of special biological interest and has implications for various human disorders that are characterized by reduced penetrance and variable expressivity.

Animals↗
PubMed1993

Genetic affinities of inbred mouse strains of uncertain origin.

Phylogenetic analyses of genetic data arising from 144 gene loci are used to describe the interrelationships among 24 widely used inbred strains of mice. An unordered-parsimony analysis gives a cladogram that is virtually identical to the known genealogy of the mouse strains. A loss-parsimony analysis is used to evaluate the hypothesis that the observed patterns of genetic divergence among these 24 strains can be explained by the segregation of residual heterozygosity arising from a small population of highly heterozygous mice. The loss-parsimony cladogram is very similar to both the unordered-parsimony cladogram and the known genealogy of the mice. The phylogenetic analyses of these 144 loci are integrated with data on the type and origin of the Y chromosome. Inclusion of the Y-chromosome data provides additional insights into the genetic composition of several of the original stocks used to produce the current inbred strains of mice. Ten strains of uncertain origin are contained in these analyses, including AKR, BUB, CE, I, NZB, P, RF, SJL, ST, and SWR. SJL is hypothesized to have been derived from the same Swiss albino stock previously used to produce SWR. The BUB strain appears to have had a complex origin and shows closest genetic similarity to SWR and ST. AKR and RF are shown to be closely related, while the I strain shows greatest genetic similarity to DBA/2 for the 144 loci. However, I and DBA possess different types of Y chromosome. The NZB strain shows genetic similarity to several stocks of both U.S. and European origins. The power of the genetic data used in these analyses reiterates that inbred strains of mice can be a valuable paradigm for studies in evolutionary biology.

Animals↗
PubMed1992

Production of chimeric hamsters by aggregation of eight-cell embryos.

Chimeric animals were produced by aggregation of 8-cell-stage embryos from two strains of hamsters (LVG and Bio 1.5). Two series of experiments were performed. In the first series, embryo pairs in contact with each other were classified as aggregates even if 2 distinct embryos could still be distinguished. Of 88 aggregates transferred, 2 chimeras were obtained. Pregnancy rate was 25%, and embryo survival was 35%. In the second set of experiments, only embryo pairs that had coalesced to form a single giant blastocyst were classified as aggregates. Of 56 aggregates transferred, 6 chimeras were obtained. Pregnancy rate was 83%, and embryo survival was 30%. Of the 8 chimeras, 6 were phenotypic males, and 2 were phenotypic females. Both females were germ line chimeras. Of the 6 males, 4 reproduced normally, 1 had abnormal external genitalia but normal spermatogenesis, and 1 was sterile and had atrophic testes. Each of the fertile males transmitted only a single component, either the LVG or the Bio 1.5. Examination of the testes from the sterile chimera revealed that in excess of 80% of the seminiferous cords were devoid of germ cells. These results demonstrate that hamster chimeras can be obtained by aggregation of 8-cell-stage embryos.

Animals↗
PubMed2004

Anesthetic requirement is increased in redheads.

BACKGROUND: Age and body temperature alter inhalational anesthetic requirement; however, no human genotype is associated with inhalational anesthetic requirement. There is an anecdotal impression that anesthetic requirement is increased in redheads. Furthermore, red hair results from distinct mutations of the melanocortin-1 receptor. Therefore, the authors tested the hypothesis that the requirement for the volatile anesthetic desflurane is greater in natural redheaded than in dark-haired women. METHODS: The authors studied healthy women with bright red (n = 10) or dark (n = 10) hair. Blood was sampled for subsequent analyses of melanocortin-1 receptor alleles. Anesthesia was induced with sevoflurane and maintained with desflurane randomly set at an end-tidal concentration between 5.5 and 7.5%. After an equilibration period, a noxious electrical stimulation (100 Hz, 70 mA) was transmitted through bilateral intradermal needles. If the volunteer moved in response to stimulation, desflurane was increased by 0.5%; otherwise, it was decreased by 0.5%. This was continued until volunteers "crossed over" from movement to nonmovement (or vice versa) four times. Individual logistic regression curves were used to determine desflurane requirement (P50). Desflurane requirements in the two groups were compared using Mann-Whitney nonparametric two-sample test; P < 0.05 was considered statistically significant. RESULTS: The desflurane requirement in redheads (6.2 vol% [95% CI, 5.9-6.5]) was significantly greater than in dark-haired women (5.2 vol% [4.9-5.5]; P = 0.0004). Nine of 10 redheads were either homozygous or compound heterozygotes for mutations on the melanocortin-1 receptor gene. CONCLUSIONS: Red hair seems to be a distinct phenotype linked to anesthetic requirement in humans that can also be traced to a specific genotype.

Adult↗
PubMed2005

Increased sensitivity to thermal pain and reduced subcutaneous lidocaine efficacy in redheads.

BACKGROUND: Anesthetic requirement in redheads is exaggerated, suggesting that redheads may be especially sensitive to pain. Therefore, the authors tested the hypotheses that women with natural red hair are more sensitive to pain and that redheads are resistant to topical and subcutaneous lidocaine. METHODS: The authors evaluated pain sensitivity in red-haired (n = 30) or dark-haired (n = 30) women by determining the electrical current perception threshold, pain perception, and maximum pain tolerance with a Neurometer CPT/C (Neurotron, Inc., Baltimore, MD). They evaluated the analogous warm and cold temperature thresholds with the TSA-II Neurosensory Analyzer (Medoc Ltd., Minneapolis, MN). Volunteers were tested with both devices at baseline and with the Neurometer after 1-h exposure to 4% liposomal lidocaine and after subcutaneous injection of 1% lidocaine. Data are presented as medians (interquartile ranges). RESULTS: Current perception, pain perception, and pain tolerance thresholds were similar in the red-haired and dark-haired women at 2,000, 250, and 5 Hz. In contrast, redheads were more sensitive to cold pain perception (22.6 [15.1-26.1] vs. 12.6 [0-20] degrees C; P = 0.004), cold pain tolerance (6.0 [0-9.7] vs. 0.0 [0.0-2.0] degrees C; P = 0.001), and heat pain (46.3 [45.7-47.5] vs. 47.7 [46.6-48.7] degrees C; P = 0.009). Subcutaneous lidocaine was significantly less effective in redheads (e.g., pain tolerance threshold at 2,000-Hz stimulation in redheads was 11.0 [8.5-16.5] vs. > 20.0 (14.5 to > 20) mA in others; P = 0.005). CONCLUSION: Red hair is the phenotype for mutations of the melanocortin-1 receptor. Results indicate that redheads are more sensitive to thermal pain and are resistant to the analgesic effects of subcutaneous lidocaine. Mutations of the melanocortin-1 receptor, or a consequence thereof, thus modulate pain sensitivity.

Adult↗
PubMed1993

Scrotal construction by expansion of labia majora in biological female transsexuals.

Construction of male genitalia in biological female transsexual patients is problematic. We report 3 transsexuals with scrotal construction by tissue expansion of the labia majora. In each patient, tissue expanders were inserted into the labia majora several months before free flap phalloplasty. In 2 patients, the tissue expanders were removed, and testicular implants were placed into the labial pockets. In the other patient, the tissue expanders were left in place. Because of the close embryological relationship between the labia majora and the scrotum, the neoscrotum appears natural in color match, hair pattern, and skin texture. The anatomical position of the labia majora produces a scrotum properly located in relation to surrounding anatomical structures. Excellent aesthetic results can be achieved with this procedure. Based on our experience, we advocate this procedure for scrotal construction in biological female transsexual patients.

Adult↗
PubMed1996

Genotype-phenotype correlations in type 1 Waardenburg syndrome.

Type 1 Waardenburg syndrome (WS1) is an autosomal dominant disorder characterized by dystopia canthorum, sensorineural deafness, and pigmentary disturbances. Previous work has linked the disease to PAX3, a transcription factor with two highly conserved DNA binding motifs: a paired box and a homeobox. Several mutations within the paired box of PAX3 have been reported. We have identified the first two mutations within the homeobox in two different families. Herein, we report the phenotypic expression of WS1 in these two families and explore the implications for possible genotype-phenotype correlations. The phenotypic expression was variable within and between the families. Sensorineural hearing loss was present in 71% of affected individuals. Spectrum of hearing loss included unilateral high frequency (>4000 Hz), profound unilateral hearing loss, and bilateral profound hearing loss. The severity of hearing impairment varied significantly within and among families. Phenotypically, these two WS1 families with mutations within the PAX3 homeobox could not be differentiated from those families with paired box mutations. More precise genotype/phenotype correlation may be possible when additional mutations are described throughout the PAX3 gene.

Base Sequence↗