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Biomedical subjects

D Bixler

Publications and source records attributed to D Bixler.

At least 73 records · Page 4Linked to original sources
PubMed1981

Dominant inheritance of velopharyngeal incompetence.

A family is described in which a girl, two boys and their father showed speech hypernasality. A half-sib, a grandfather, a great-aunt, and a cousin of these sibs also showed a similar speech defect. Analysis of recorded speech of the father and three sibs revealed articulation deficiencies in addition to hypernasality. Intra-oral examination and neurologic evaluation of the cranial nerves failed to reveal any abnormality in palate morphology or cranial nerve function. Psychometric and audiometric studies of the affected did not contribute to an explanation of the defect. Speech cinefluoroscopy and cephalometric radiographs confirmed that the speech defect involved velopharyngeal incompetence resulting from an anatomic disproportion of the velopharyngeal structures. The family pedigree supports the concept that this type of nasal speech, resulting from disproportion of velopharyngeal structures, is transmitted as an autosomal dominant trait.

Adolescent↗
PubMed1980

Cleft lip+/-cleft palate: an overview of the literature and an analysis of Danish cases born between 1941 and 1968.

In recent years there has been some controversy over the analytical designs and the meaning of varying results with regard to studies of facial clefting and other common congenital malformations. Regardless, it is still unclear as to the nature of the genetic and environmental components of the etiology as well as the nature of the relevant pathogenetic mechanisms. Despite claims to the contrary, the predictions of a particular multifactorial/threshold inheritance (MF/T) model delineated by Carter [1977d] and others are not well supported by studies worldwide. The present study population consists of 1,895 persons born in Denmark with cleft lip with or without cleft palate (CL +/- P) between 1941 and 1968. A test of the MF/T predictions revealed the following: 1) the incidence of CL +/- P in siblings was 40 X greater than that in the general population 2) the risk to siblings of CL +/- P females was not significantly different from the risk to siblings of CL +/- P males; 3) recurrence risk for siblings of CL +/- P probands was dependent upon the proband's cleft type; 4) only 0.4% of the variation in risk to the siblings born after the proband could be accounted for by the number of previously affected siblings; 5) the consanguinity rate was 6 times less than the general population rate; 6) heritability estimates from siblings and parents by sex suggest, either the presence of significant dominance effects, or a common sibling environment component in the etiology of the disorder. Further, testing with a multiple-sex threshold method, designed and provided us by [Kidd and Spence, 1976] revealed that neither the MF/T nor single-major locus with random environmental variation provided a good fit. In light of recent experimental mouse and human data, an alternative model of monogenic-dependent susceptibility to a variety of teratogens is discussed.

Cleft Lip↗
PubMed1980

The syndrome of multisynostotic osteodysgenesis with long-bone fractures.

Described here are two patients with a newly recognized syndrome of bone and cartilage maldevelopment which, we believe, results from a single embryonic defect, probably of genetic origin. The cardinal manifestations of this association are craniosynostosis, radiohumeral synostosis (RHS), and femoral bowing. Specific secondary defects include midface hypoplasia with characteristic facial appearance and ears, neonatal femoral fractures, and multiple minor anomalies of the limbs. Though the differential diagnosis includes such disorders as the campomelic syndrome, osteogenesis imperfecta (OI) and certain of acrocephalosyndactyly syndromes, the unique combination of clinical and radiographic abnormalities allows ready differentiation. The cause cannot be determined from these two cases.

Bone Diseases, Developmental↗
PubMed1980

Misconceptions about dental treatment for patients with genetic disease.

It is the goal of this conference to define the role of dentistry to the interdisciplinary treatment of genetic diseases. Certainly, with the inclusion of dental disciplines in centers devoted to the diagnosis and treatment of genetic disease, the diagnosis and treatment of secondary craniofacial manifestation and the diagnosis and treatment of genetic disease primary to the craniofacial and oral complex will be greatly accelerated and the many misconceptions about dental treatment for patients with any genetic disease will be significantly reduced.

Dental Care↗
PubMed1979

The human X-chromosome and the levels of serum immunoglobulin M.

The serum concentrations of immunoglobulins G, A and M were measured in a sample of 93 pairs of monozygotic twins, their spouses, and their offspring. The hypothesis that the human X-chromosome carries genes which control the levels of immunoglobulin M was tested with three different approaches. Our results indicate that environmental factors are primarily responsible for the observed variation in the levels of IgG and IgA. The variance of IgM seems to be mostly the result of X-linked gene effects, with women having higher IgM levels than men.

Female↗
PubMed1979

Analysis of intrafamilial correlations, serum levels of IGM and the human X-chromosome.

The serum concentrations of immunoglobulin M (IgM) were measured in a sample of 93 monozygotic twin pairs, their spouses, and their offsprings. The hypothesis that the human X chromosome carries genes that control the levels of IgM was tested with two different approaches neither one of which provided conclusive evidence to support the IgM X-linked gene hypothesis.

Female↗
PubMed1979

Facial clefts in Danish twins.

A total of 74 Danish twin pairs with cleft lip +/- palate (CL(P)) and isolated cleft palate (CP) born in Denmark from 1941 to 1969 were studied. Eight pairs were of indeterminate zygosity status' and 26 pairs of unlike sex were dizygous (DZ). Of the remaining 42 like-sexed pairs, zygosity assignments were made from genotyping and physical resemblance data. Twelve pairs were given MZ status and thirty pairs DZ status. The following data was calculated: 1) in contrast to other reports, the incidence of either CL(P) or CP was not increased for either MZ or DZ twins; 2) using the pairwise method for concordance rate calculation, concordance rates for CL(P) twins were: MZ = 36 per cent; DZ = 1.5 per cent. For CP, MZ = 33 per cent; DZ = 0 per cent. The results support the concept that heredity is a prime factor in the etiology of clefting, but the low MZ concordance rates also suggest genetic heterogeneity in this cleft population.

Cleft Lip↗
PubMed1978

Multiple pterygium syndrome.

After treating a 12-year-old patient with multiple pterygium syndrome, we ascertained the minimal diagnostic criteria of pterygia in the neck, axilla, antecubital, and even popliteal areas; evidence supports autosomal recessive inheritance for this syndrome.

Adult↗
PubMed1978

Linkage studies in Van der Woude syndrome.

A newly ascertained kindred segregating Van der Woude syndrome through four generations is described. Linkage studies using the methods of Ott (1974) were carried out using 19 marker loci.

Amylases↗
PubMed1978

Linkage analysis in dominant acrocephalosyndactyly.

Linkage analysis was performed on a previously reported family in which multiple dominantly inherited acrocephalosyndactyly syndromes were present. An underlying axiom of linkaged analysis is that the trait analysed be monogenic. This prerequisite was presumptively established in the single kindred analysed because acrocephalosyndactyly was observed in multiple cases in multiple generations.

Acrocephalosyndactylia↗
PubMed1977

Dentin dysplasia, type II: a rare autosomal dominant disorder.

Dentin dysplasia, Type II, is a rare autosomal dominant disorder. The primary teeth are amber and translucent and the pulp chambers are obliterated. The permanent teeth have a normal to brown-gray coloration and a thistle-tube pulp configuration with multiple true denticles. To date, only five families with this disorder have been reported. This article presents two additional families. Light and scanning electron microscopy of an affected primary incisor showed the dentin, including the mantle layer, to be highly disorganized throughout. Possible pathogenic events associated with the phenotype are discussed.

Adolescent↗