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Biomedical subjects

W G Pearce

Publications and source records attributed to W G Pearce.

At least 37 records · Page 2Linked to original sources
PubMed1993

Manifestations of X-linked congenital stationary night blindness in three daughters of an affected male: demonstration of homozygosity.

X-linked congenital stationary night blindness (CSNB1) is a hereditary retinal disorder in which clinical features in affected males usually include myopia, nystagmus, and impaired visual acuity. Electroretinography demonstrates a marked reduction in b-wave amplitude. In the study of a large Mennonite family with CSNB1, three of five sisters in one sibship were found to have manifestations of CSNB1. All the sons of these three sisters were affected. Each of the two nonmanifesting sisters had at least one unaffected son. Analysis of Xp markers in the region Xp21.1-Xp11.22 showed that the two sisters who were unaffected had inherited the same maternal X chromosome (i.e., M2). Two of the daughters who manifested with CSNB had inherited the other maternal X chromosome (M1). The third manifesting sister inherited a recombinant X chromosome with a crossover between TIMP and DXS255, which suggests that the CSNB1 locus lies proximal to TIMP. One of the affected daughters' sons had inherited the maternal M1 X chromosome, a finding consistent with that chromosome carrying a mutant CSNB gene; the other affected sons inherited the grandfather's X chromosome (i.e., P). Molecular analysis of DNA from three sisters with manifestations of CSNB is consistent with their being homozygous at the CSNB1 locus and with their mother being a carrier of CSNB1.

Adolescent↗
PubMed1992

Mapping of locus for X-linked congenital stationary night blindness (CSNB1) proximal to DXS7.

A recombinant chromosome in a male affected with X-linked congenital stationary night blindness (CSNB1) provides new information on the location of the CSNB1 locus. A four-generation family with five males affected with X-linked CSNB was analyzed with five polymorphic markers for four X-chromosome loci spanning the region OTC (Xp21.1) to DXS255 (Xp11.22). Four of the males inherited the same X chromosome; one male inherited a chromosome that from OTC to DXS7, inclusive, was derived from the normal X chromosome of his unaffected grandfather and that from a location between DXS7 and DXS426 proximally was derived from the chromosome carrying the CSNB1 locus. This recombinant maps the CSNB1 locus in this family to a region on the short arm of the X chromosome proximal to the DXS7 locus.

Alleles↗
PubMed1991

Autosomal dominant megalocornea with congenital glaucoma: evidence for germ-line mosaicism.

After the presentation of a newborn with congenital glaucoma, four additional members in two generations of a family were found to be affected with megalocornea. The absence of the disorder in the parents of three affected siblings can be explained by autosomal recessive inheritance, autosomal dominant inheritance or germ-line mosaicism. Each affected member showed iris stroma hypoplasia, miotic pupils and defects of the iris pigment epithelium. Less frequently encountered features included increased axial length, high myopia and congenital cataract. Most of the abnormalities can be accounted for by a disturbance in the growth and development of neural crest cells of the anterior chamber angle.

Adult↗
PubMed1990

A locus for X-linked congenital stationary night blindness is located on the proximal portion of the short arm of the X chromosome.

Linkage between X-linked congenital stationary night blindness (CSNB1) and seven markers on the X chromosome was investigated in a large four-generation Albertan kindred. We detected significant linkage between the CSNB1 locus and the locus DXS255 (maximum lod score = 6.73 at a recombination fraction of 6%; confidence interval of 1% to 18%), which anchors the CSNB1 locus to the proximal region near p11.22 on the short arm of the X chromosome.

Female↗
PubMed1990

Recession of the superior oblique tendon in A-pattern strabismus.

We performed 9 to 12 mm of recession of the superior oblique tendon for A-pattern strabismus in 10 patients. The average preoperative A-pattern measured 29.4 prism dioptres (PD), and the average pattern correction was 29.3 PD. All patients had a residual pattern of 6 PD or less (average 2.3 PD). No patient experienced significant underaction of the superior oblique, and other surgical complications, such as ptosis, Brown's syndrome, and laceration of the vortex vein or superior rectus, did not occur. The procedure corrected 14 to 40 PD of A-pattern. The amount of pattern corrected was correlated with the size of the preoperative A-pattern but not with the total amount of recession done. No significant shift in esodeviation in primary position was noted in the patients who underwent only superior oblique recession. The procedure appears to be of particular value in patients with moderate superior oblique overaction. The advantages of recession of the superior oblique tendon include the potential for reversibility and reoperation, low risk of induced superior oblique palsy, allowance for asymmetric surgery and potential for adjustable suture technique.

Accommodation, Ocular↗
PubMed1990

Variable expressivity in X-linked congenital stationary night blindness.

X-linked congenital stationary night blindness (CSNB) is a well-documented disorder in which the most striking clinical features are impaired night vision, nystagmus and myopia. Recent reports have highlighted differing features between families, and it has been suggested that these discrepancies may be the result of two loci on the X chromosome or of two mutant alleles. We outline the clinical and visual function findings in 42 affected members from 10 families and 1 adopted person. There was a relative unawareness of the disorder in clinical practice. At least one of the main features of CSNB was absent in 75% of the patients. The visual function values varied widely, both between and within families (visual acuity 20/30 to 20/400, refractive error +1.50 to -22.50 and rod segment elevation 1.5 to 3.0 log units). The findings are consistent with a single allele exhibiting a wide variation in clinical expression.

Adolescent↗
PubMed1989

Inferior rectus muscle restriction after retrobulbar anesthesia for cataract extraction.

Among the recognized complications of retrobulbar anesthesia, postoperative permanent diplopia has rarely been reported. We describe two patients with inferior rectus muscle restriction after retrobulbar anesthesia for cataract extraction and intraocular lens implantation. Both did well after inferior rectus recession with placement of an adjustable suture.

Aged↗
PubMed1987

Autosomal recessive juvenile cataract in Hutterites.

Autosomal recessive inheritance of juvenile cataract is described amongst several related sibships of Lehrerleut Hutterites. The main features of the cataract include onset between three and seven years of age; rapid progression to maturity within one to three months; normal intelligence; no systemic associations, and no urinary reducing substances and normal erythrocyte galactokinase activity. Genetic analysis demonstrates the close relationship between parents of affected sibships with a coefficient of inbreeding of affected sibships of 0.0512. Estimates of heterozygote frequency within Lehrerleut Hutterites at 0.128 indicate that if current inbreeding practice continues additional cases can be expected.

Alberta↗
PubMed1986

Corneal involvement in autosomal dominant coloboma/microphthalmos.

Peripheral corneal opacification in the line of closure of the embryonic fissure associated with hyperopic astigmatism and anisometropic amblyopia was identified in two eyes of two members of a family with isolated autosomal dominant coloboma-microphthalmos. A review of the literature disclosed no previously reported cases. It would appear that the gene for isolated coloboma-microphthalmos can affect the growth and differentiation of mesenchymal cells of neural crest origin, as well as the neuroectodermal tissues of the embryonic fissure.

Adult↗
PubMed1985

Variable severity in autosomal dominant optic atrophy.

There are some indications in the literature on autosomal dominant optic atrophy that there are two genetic types - a congenital and a post-natal. This paper reviews the ocular findings of three affected members of a family with autosomal dominant optic atrophy - a father and two daughters - which appear to fit the criteria for a 'congenital' type of optic atrophy. Comparison with an additional 17 cases indicates that those with an early or congenital onset are at the more severe end of a distribution curve of involvement. The less severely affected patients were older and often had passed many years with little or no visual difficulties. Such variation is a recognized feature of autosomal dominant inheritance and is the basis for suggesting that there is probably only one genetic locus for autosomal dominant optic atrophy.

Adolescent↗
PubMed1984

Adjustable sutures: experimental assessment of final muscle position.

The likelihood of forward "creep" of muscles recessed with the use of adjustable loops of suture in the correction of strabismus was investigated. Twelve orthotropic dogs underwent both regular and loop recessions of the lateral and medial rectus muscles; the data for two of the dogs were excluded because of loss of muscles. Three months later it was found that in the majority of cases the recessed muscles had minimally advanced from the position of surgical placement. Although the type of recession made little difference to the results, the mean forward creep was much greater for the medial rectus muscles (1.55 +/- 0.68 mm [p less than 0.01] and 2.00 +/- 2.44 mm [p = 0.09] for those undergoing regular and loop recessions respectively) than for the lateral rectus muscles (0.35 +/- 0.58 mm and 0.60 +/- 0.62 mm respectively). During the operations the amount of contraction of the medial rectus muscle had been noted to vary. It is likely that in some instances the tension on the suture loops was insufficient to hold them taut, and the muscles therefore adhered to the sclera at variable sites. Hence, adequate intrinsic muscle tone may be important for predictable clinical results of loop recession.

Animals↗
PubMed1984

Bardet-Biedl syndrome and retinitis punctata albescens in an isolated northern Canadian community.

Autosomal recessive inheritance of various conditions is well documented among inbreeding groups. In northern Canada inbreeding occurs in communities as a result of language and cultural uniqueness as well as geographic isolation. In one such community--Rae, in the Northwest Territories--two autosomal recessive disorders, the Bardet-Biedl syndrome and retinitis punctata albescens, are segregating. This report outlines the major clinical features of the disorders, establishes for both conditions the high frequency of the heterozygous carrier genotype in the community and suggests a possible way to reduce the likelihood of increased numbers of affected individuals in forthcoming generations.

Adolescent↗
PubMed1983

Autosomal dominant iridogoniodysgenesis: glaucoma management.

In a family of 55 people in seven generations 28 were known to be affected with autosomal dominant iridogoniodysgenesis. Their glaucoma was characterized by early onset of high intraocular pressures, lability of the pressure both with and without medical treatment, poor response to such treatment and resistance of the optic nerve head to damage even into early middle age. Among the surgical procedures undertaken, goniotomy was not successful but, oddly, iridencleisis was. All indications were that surgery could be delayed into adult life.

Adolescent↗
PubMed1983

Autosomal dominant iridogoniodysgenesis: genetic features.

Twenty-two members of two families have been identified as being affected with iridogoniodysgenesis. The major clinical features of this disorder are mesodermal remnants in the iridociliary angle associated with abnormal angle vasculature, marked hypoplasia of the iris stroma and increased intraocular pressure leading to glaucoma. The involvement of the two eyes is remarkably symmetric. Pedigree analysis of the larger family provided firm evidence for regular autosomal dominant inheritance as the mechanism of genetic transmission.

Adult↗
PubMed1981

End-stage cytomegalic inclusions retinitis and disseminated intravascular coagulation.

Areas of necrosis of the retinal pigment epithelium developed in each eye of a 40-year-old renal transplant recipient. Myocardial infarctions supervened and eventually caused his death. Autopsy demonstrated cytomegalic inclusion bodies in the lungs and liver, and areas of retinal scarring and fibrin thrombi in the choriocapillaris of both eyes. The ocular features likely resulted from the resolved retinitis and preterminal disseminated intravascular coagulation.

Adult↗