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Biomedical subjects

D Loesch

Publications and source records attributed to D Loesch.

At least 19 recordsLinked to original sources
PubMed1992

Experience with direct molecular diagnosis of fragile X.

The utility of the pfxa3 probe for direct molecular diagnosis of the fragile X (FRAXA) has been established. This probe detects amplification of an unstable DNA element consisting of variable length CCG repeats. The size of the amplified fragment is correlated with phenotype and was determined using PstI digested DNA in family members. In 35 families with the fragile X, there was correspondence in 183 cases between the presence of an amplified unstable element and the presence of the fragile X chromosome independently determined by cytogenetics, position in the pedigree, or linked DNA markers flanking the fragile X. There was also correspondence in 124 cases between the presence of the normal 1.0 kb PstI fragment and absence of the fragile X chromosome independently determined by linked flanking markers. Six additional families considered to be isolated cases of 'fragile X' had been diagnosed before recognition of FRAXD. The pfxa3 probe confirmed the cytogenetic diagnosis in three families, the other three being rediagnosed as non-fragile X. A further two families had consistent expression of a different folate sensitive fragile site, FRAXE, close to FRAXA but not associated with fragile X syndrome and not detectable with the pfxa3 probe. Subsequent referrals were received from additional family members or from members of new families for whom carrier status had not been predetermined by linked markers. Direct pfxa3 diagnosis for the 135 females within these 222 additional cases was confirmed by dosage analysis with the control probe pS8.(ABSTRACT TRUNCATED AT 250 WORDS)

Artifacts↗
PubMed1992

Fragile-X syndrome: unique genetics of the heritable unstable element.

The fragile site at Xq27.3 is an unstable microsatellite repeat, p(CCG)n. In fragile-X syndrome pedigrees, this sequence exhibits variable amplification, the length of which correlates with fragile-site expression. There is a direct relationship between increased p(CCG)n copy number and propensity for instability: individuals having large amplifications exhibit somatic variation due to increased instability. The instability of the p(CCG)n repeat, when transmitted through affected pedigrees, explains the unusual segregation patterns of fragile-X phenotype, referred to as the Sherman paradox. All individuals of fragile-X genotype were found (where testing was possible) to have a parent with amplified p(CCG)n repeat, indicating that few, if any, cases of fragile-X syndrome are not familial.

Blotting, Southern↗
PubMed1984

Evidence for polygenic epistatic interactions in man?

Studies of multifactorial inheritance in man have ignored nonadditive gene action or attributed it entirely to dominance. Reanalyses of dermatoglyphic data on monozygotic and dizygotic twins, siblings and parents and offspring suggest that a substantial proportion of variation in total finger pattern intensity is due to epistatic interactions between additive genetic deviations, not dominance. Bootstrapping and power simulations support this interpretation of the data. We believe this is the strongest evidence so far for polygenic epistasis in man.

Dermatoglyphics↗
PubMed1983

Dermatoglyphic sole patterns in 21 trisomics.

Frequencies of loop patterns on the proximal sole have been estimated in the sample of 21 trisomic subjects and compared with those previously obtained in a sample of normal individuals. Results indicate that, in Down's syndrome, a lowered pattern intensity, characteristic of the distal sole does not occur on the proximal sole. Studies of patterns on the proximal portion of the sole should be pursued using larger samples of 21 trisomics, providing that care is taken to obtain the best quality footprints; the main limitation in such studies is in the common occurrence of ridge dissociation. In addition, some previous estimates of the frequency of zygodactylous triradii on the distal sole have been reconsidered on the basis of the results obtained in the present sample of footprints with complete recording of areas under the toes.

Dermatoglyphics↗
PubMed1982

Directional and absolute asymmetry of digital ridge counts.

Distributions, correlations and weighted least squares estimates of the components of variation in right-left asymmetry for individual finger ridge counts have been obtained from 221 pairs of twins and 80 pairs of opposite sex siblings. Asymmetry has been measured by two indices: signed right-left difference representing unidirectional asymmetry and absolute difference, representing ambidirectional asymmetry. The results indicate that both types of asymmetry are largely under environmental control, but with significant genetic components, particularly in males. The proportion of genetic variation in these measures of asymmetry varies somewhat between individual fingers.

Dermatoglyphics↗
PubMed1981

Dermatoglyphic studies in the parents of trisomy 21 children I. Distribution of dermatoglyphic discriminants.

A sample of 312 parents of a child with complete trisomy 21 (168 mothers and 144 fathers) has been compared with 295 parents of non-mongol children (61 mothers and 134 fathers) with respect to distribution of individual dermatoglyphic discriminant scores. Selection of dermatoglyphic traits as well a weightings have been based on the discriminant function, constructed for normal controls against cytogenetically diagnosed trisomy 21 mosaics. The results indicate that the proportion of individuals with an increased chance of mosaicism is appreciably greater in a sample of both the mothers and the fathers of mongol children, as compared with the parents of non-mongol children. For D greater than + 3.00, including also the overlap range values, it is, on the average, twice as high as in the control parents, while for the D values greater than + 4.00, strongly indicative of mosaicism, it is about five times higher than in control parents. This is so in spite of the fact that all parents, who had previously been cytogenetically tested and diagnosed as mosaics, were not included in this sample. Although the meaning of these results cannot yet be completely understood, they justify the extension of the use of dermatoglyphic discriminants in studies on parental mosaicism in trisomy 21.

Age Factors↗
PubMed1979

An outbreak of infections caused by strains of Staphylococcus aureus resistant to methicillin and aminoglycosides. I. Clinical studies.

In a 22-month period, strains of Staphylococcus aureus resistant to methicillin and multiple aminoglycosides, (designated MARS) were recovered from 108 inpatients with nosocomial infections at a hospital in the midwestern United States. Sixty-six of these patients were staying in a burn unit, and 42 were on other hospital wards. Among the patients with burns, MARS were recovered from the burn wounds of 64%; 32% of the patients with burns had MARS bacteremia. The patients without burns were age-matched with patients with nosocomial infections caused by antibiotic-susceptible strains of S. aureus. Patients from whom MARS were isolated had a longer mean hospital stay (79.6 days vs. 36.9 days; P less than 0.01), developed infection later (26.5 days vs. 13.5 days after admission; P less than 0.01), and had received antibiotic therapy before infection more often (81% vs. 38% of patients; P less than 0.01) than patients in the comparative population. Types of infection and incidences of death and bacteremia were similar in the two groups. Antibiotic-resistant strains of S. aureus may cause serious infections and significant mortality.

Aminoglycosides↗
PubMed1979

Dermatoglyphic distances and position of 21 trisomy mosaics.

The position of 21 trisomy mosaics with an average proportion of trisomic cells approximating 0.5 in relation to normal subjects and those with complete 21 trisomy has been evaluated by means of dermatoglyphic distances, using samples of 142 mosaics, 302 normal controls and 225 complete 21 trisomics for males and females separately and combined. Distances were calculated by means of the simplified D2k method. Penrose's "size and shape" analysis of variance has been applied for comparison to obtain distance coefficients, C2H, based on pattern intensities. Results indicate that mosaics are not intermediate but much closer to 21 trisomics in spite of the fact that the average proportion of trisomic cells in blood approximates 0.5; secondly, that the degree of deviation from the intermediate position of the mosaic sample is roughly proportional to the degree of cytological mosaicism. The position of mosaics is appreciably more intermediate in respect of finger-tip patterns than in respect of palmar and sole loops and triradii. The results obtained here have thus given evidence for the usefulness of dermatoglyphic distances, which enable all the differences in frequencies or means of the respective characters to be conveniently represented by a single number, in studies of the abnormal development of phenotypic characteristics in cases of incomplete trisomy.

Dermatoglyphics↗
PubMed1979

Genetical studies of the palmar and sole patterns and some dermatoglyphic measurements in twins.

The within- and between-pair mean squares and means have been estimated for dermatoglyphic patterns on finger-tips, palms and soles and compared between samples of 110 MZ and 111 DZ twins of Polish origin. Dermatoglyphic patterns have been represented by topologically significant pattern elements (loops and triradii) on finger-tips, palms and soles, considered separately and in various combinations, ridge counts on finger-tips and on palms and several other palmar and sole measurements. Some genetic parameters such as: genetic variance (GCT) based on within and between mean squares of the two types of twins, the within-pair variance ratio and the covariance/variance ratio in MZ twins have also been obtained for all these traits and considered in relation to differences in respect of the total and between-pair variances and means for all specified characters. The highest values of genetic parameters have been obtained for pattern intensities and ridge counts on finger-tips, considered separately or combined, for the H hypothenar loop and the axial t triradii on palms, and for the majority of sole loops and triradii. The lowest values have been found for several palmar loops and measurements such as minutiae counts. These results are, in respect of some pattern elements, not in agreement with the estimated heritability based on correlations between other relatives. A comparison of genetic parameters for single loops or triradii and for their various combinations indicates that some pattern elements or their combinations may be each influenced by a specific genetic system which modifies their phenotypic expression. It is believed that the obtained results are, for some proportion of characters, clearly biased by inequality of the total variances in MZ and DZ twins.

Analysis of Variance↗
PubMed1978

Dermatoglyphic total patterns on palms, finger-tips and soles in twins.

110 palms of MZ twins and 111 like-sexed pairs of DZ twins have been compared in respect of a concordance rate of the palmar, sole and finger-tip total pattern types. Dermatoglyphic patterns have been classified according to the topological method, and the distributions of the numbers of discordant pattern elements from homolateral, heterolateral and bilateral comparisons in MZ and DZ twins, respectively, are presented. The highest concordance occurs in homolateral comparisons in MZ twins and the lowest in heterolateral comparisons. Bilateral concordance is highest for sole and finger-patterns, while palmar patterns present a considerable degree of dermatoglyphic asymmetry. Palmar, sole and finger-tip patterns are also not alike in homolateral concordance rates within MZ and DZ twin pairs. The differences between MZ and DZ twins are much more pronounced for sole patterns than for palmar or finger-tip patterns, which is also reflected in the estimated H values. For soles, this may be in some way related to the considerable symmetry of patterns. The fact that some pattern elements are intercorrelated may also introduce a bias in estimates of heritability, based on twin material.

Dermatoglyphics↗
PubMed1978

Genetical distance and dermatoglyphic characters. II. Intrapopulation distance coefficients.

This paper attempts to evaluate the dermatoglyphic (genetical) distance between two Polish population samples in relation to the intrapopulation distance coefficients estimated within each sample. All the coefficients have been based, in turn, on frequencies of fingertip, palmar and sole pattern elements, separately and for all characters combined. The results of a comparison of various combinations of dermatoglyphic characters with one another in respect of all successive values of a distance coefficient indicate that, if populations of mostly related individuals were compared, sole patterns have been the most efficient ones in differentiating between the two normal population samples. The values of inter- and intrapopulation distance coefficients obtained from samples consisting mostly of family units have been compared with those estimated in samples of non-related individuals. The limitations and difficulties in the interpretation of the values of a distance coefficient related both to the material used and statistical procedures are discussed.

Dermatoglyphics↗
PubMed1978

Genetical distance and dermatoglyphic characters. III. Dermatoglyphic distances within twin pairs, between left and right sides and between normals and 21-trisomics.

The dermatoglyphic (genetical) distance coefficients have been estimated within monozygotic and dizygotic twin pairs, between left and right sides of the same individual and between normal subjects and 21-trisomics. All the coefficients have been based, in turn, on frequencies of fingertip, palmar and sole pattern elements, separately and for all characters combined. Quantitative variables (pattern intensities) have also been used for independent evaluation of the C2H distance coefficient in monozygotic and dizygotic twins, and in 21-trisomics as compared with normal individuals. The values of a distance have then been considered in relation to the degree of genetical likeness between the compared items as well as to the relative contribution of each pattern combination to the overall value of a distance. Some limitations in the interpretation of the results, connected mainly with statistical procedures, are also discussed.

Chromosomes, Human, 21-22 and Y↗
PubMed1977

Topologically significant dermatoglyphic patterns in twins.

A total of 58 dermatoglyphic characters, consisting of topologically significant pattern elements, i.e., loops and triradii, on palms, soles and fingertips, were tested in a sample of 110 MZ and 111 like-sexed DZ twin pairs. The analysis included homolateral, heterolateral and bilateral concordance rates, the derived Hc coefficient, coefficients of the within-pair association, phi, derived chi2 intraclass correlation coefficients and heritability estimates based on variances (h2) and correlations (Hr), and the variance ratio F. A considerable difference was found in respect of "heritability" values between palmar and sole patterns, in that they are the highest for sole loops and triradii and the lowest for most palmar loops. These data are compared with the h2 values obtained from family correlations. The difficulties in the interpretation of "heritability" estimates based on the material of twins are pointed out and particular attention is drawn to a possibility of the additional bias in twin studies related to a degree of symmetry of the characters investigated.

Dermatoglyphics↗
PubMed1976

Genetical distance and dermatoglyphic characters. I. Interpopulation distance coefficients.

The distance coefficients between two relatively isolated population groups in Poland, based on various combinations of dermatoglyphic non-measurable characters were estimated. These were compared with the overall dermatoglyphic distance coefficients estimated separately for left and right, as well as with the serologic distance coefficient, based on ABO, Rh and Duffy blood groups. Dermatoglyphic distance coefficients, estimated from quantitative variables (pattern intensities) using Penrose's C2H analysis of variance method, were also introduced for a comparison. The differences in frequencies between two populations, separately for each character, were also compared with its heritability values.

ABO Blood-Group System↗