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Biomedical subjects

G N Wilson

Publications and source records attributed to G N Wilson.

At least 55 records · Page 3Linked to original sources

Intracranial angioblastic meningioma and an aged appearance in a woman with Rubinstein-Taybi syndrome.

Here we report on a 39-year-old woman with severe mental retardation, short stature, unusual face with prominent nose, broad thumbs, and broad first toes diagnostic of the Rubinstein-Taybi syndrome. Following admission because of headache and anorexia, a bifrontal lobe neoplasm was excised and diagnosed as an angioblastic meningioma. The unusual tumor and aged appearance of the patient add 2 facets to the natural history of Rubinstein-Taybi syndrome.

Abnormalities, Multiple↗

Maternal meiosis II nondisjunction in a case of 47,XXY testicular feminization.

An 11-year-old patient with incomplete testicular feminization and a 47,XXY karyotype is described. The patient had female external genitalia, clitoromegaly, and some features of Klinefelter's syndrome, including speech delay and delayed intellectual development. DNA analysis using X chromosomal DNA sequences suggest that the supernumerary X chromosome in the patient resulted from maternal nondisjunction during meiosis II. The M II error thereby provides the basis for homozygosity of a mutation in the androgen receptor locus.

Androgen-Insensitivity Syndrome↗

Office approach to the genetics patient.

Knowledge of a few disease categories and their associated laboratory tests can award the pediatrician full partnership in the management of genetic disease. The provision of a DNA test for cystic fibrosis is a recent example of the important advances occurring in genetics. Only the enlightened practitioner can ensure that patients have full and proper access to such advances.

Child↗

Pediatric approach to the skeletal dysplasias.

Named for their common impact on bone histogenesis, the category of skeletal dysplasias contains over 100 entities of sporadic, teratogenic, or genetic etiology.

Bone Diseases, Developmental↗

The frequency of aneuploidy in cultured lymphocytes is correlated with age and gender but not with reproductive history.

The clinical significance of low numbers of aneuploid cells in routine cytogenetic studies of cultured lymphocytes is not always clear. We compared the frequencies of chromosome loss and gain among five groups of subjects whose karyotypes were otherwise normal; these groups were (1) subjects studied because of multiple miscarriages, (2) parents of live borns with autosomal trisomy, (3) subjects studied because they had a relative with Down syndrome, (4) an age-matched control group of phenotypically normal adults studied for other reasons (e.g., parent of a dysmorphic child or member of a translocation family), and (5) other mostly younger and phenotypically abnormal subjects who could not be assigned to the first four groups (e.g., individuals with multiple congenital anomalies or mental retardation). No significant age, sex, or group effects were observed for autosomal loss (hypodiploidy) or gain (hyperdiploidy). Autosomal loss was inversely correlated with relative chromosome length, but autosomal gain was not. Sex-chromosome gain was significantly more frequent in females than in males, but sex-chromosome loss was not significantly different between the sexes. Significant age effects were observed for both gain and loss of sex chromosomes. When age and sex were accounted for, the frequencies of sex-chromosome loss and gain were not significantly different among the five clinical groups. In general, low numbers of aneuploid cells are not clinically important when observed in blood chromosome preparations of subjects studied because of multiple miscarriages or a family history of autosomal trisomy.

Abortion, Spontaneous↗

Glutaric aciduria type II: review of the phenotype and report of an unusual glomerulopathy.

A male infant with glutaric aciduria II secondary to electron transfer flavoprotein: ubiquinone oxidoreductase deficiency is compared to previously reported cases of glutaric aciduria II. A common pattern of anomalies in patients with malformations (8/16) includes macrocephaly, large anterior fontanelle, high forehead, flat nasal bridge, telecanthus, and malformed ears. Abnormalities such as hypotonia, cerebral gliosis, heterotopias, hepatomegaly, hepatic periportal necrosis, polycystic kidneys, and genital defects in glutaric aciduria II are reminiscent of those in Zellweger syndrome, whereas elevations of glutaric, ethylmalonic, adipic, and isovaleric acids are quite distinctive. A unique ultrastructural alteration of the glomerular basement membrane was observed in the proposita. This manifestation may represent an early stage in renal cyst formation and provide a diagnostic criterion for glutaric aciduria II when enzyme studies are unavailable.

Abnormalities, Multiple↗

Heterochrony and human malformation.

The role of altered developmental timing or heterochrony in morphologic evolution has intrigued classical and modern biologists. Analogous manifestations of developmental asynchrony occur in human dysmorphogenesis where they illustrate the residue and repertoire of phylogenetic change. Certain single malformations such as holoprosencephaly immediately suggest heterochrony by their resemblance to antecedent phylogenetic or embryologic structures. Multiple malformation syndromes of genetic, chromosomal, or teratogenic etiology may have altered developmental timing as an underlying theme. The persisting alpha-fetoprotein synthesis in ataxia-telangiectasia, the morphologic atavisms in Down or trisomy 13 syndromes, and the delayed growth or fetal to adult hemoglobin switch in diabetic embryopathy all exemplify developmental asynchrony. The perspective of heterochrony stresses the molecular history and hierarchy which is recapitulated with each pregnancy, and reconciles apparent discrepancies between the rates of molecular and morphologic evolution. Recognition of heterochrony places isolated anomalies in the context of pattern and suggests monitoring of teratogenesis through altered expression of ontogenetically regulated, phylogenetically relevant molecules.

Aneuploidy↗

Peroxisomal disorders: clinical commentary and future prospects.

Recent progress in the classification, biochemistry, and molecular biology of peroxisomal disorders is reviewed from a clinical perspective. Diseases such as Zellweger syndrome, neonatal adrenoleukodystrophy, infantile Refsum disease, hyperpipecolic acidemia, chondrodysplasia punctata, and Leber amaurosis share a common phenotype and involve deficiency of multiple peroxisomal enzymes. These disorders are associated with diverse metabolic abnormalities which are useful in pre- or postnatal diagnosis and distinguish these disorders from others such as X-linked adrenoleukodystrophy, adult Refsum disease, hyperoxaluria type I, and acatalasemia. Peroxisome structure is difficult to quantify histologically, since recent studies emphasize its developmental variability and tissue heterogeneity. The ability to manipulate this structure by dietary or pharmaceutical means provides a novel approach to therapy. At the molecular level, deficiency of peroxisomal enzymes responsible for fatty acid beta-oxidation or ether lipid synthesis reflects enhanced protein degradation due to abnormal peroxisomes; messenger RNA for the beta-oxidation enzymes is transcribed normally in peroxisomal disorders and can be increased by peroxisome proliferators. At least one integral structural protein of the peroxisome is synthesized normally in Zellweger syndrome. Hypotheses for the basic defect include defective regulation, uptake, or coenzyme stimulation of imported proteins, as well as defective biosynthesis. One clue to this defect may be a similar evolutionary history of peroxisomes and mitochondria which would explain their common alteration in Zellweger syndrome.

Adrenoleukodystrophy↗

MCA/MR syndrome in a female infant with tetraploidy mosaicism: review of the human polyploid phenotype.

We report on a 3-month-old girl with unusual facial appearance, short neck with low posterior hairline, wide chest, valvular pulmonic stenosis, abnormal fingernails, and diploid-tetraploid mosaicism (46,XX/92,XXXX in 7.2% of peripheral leucocytes and in 29% of skin fibroblasts). Comparison with 11 previously reported cases with mosaic or complete tetraploidy does not establish an easily recognizable syndrome. However, a malformation pattern is apparent when tetraploidy patients are compared with 14 cases of triploid mosaicism and 44 previously reported cases of nonmosaic triploidy. A history of sex hormone exposure was present in 5 of 11 pregnancies resulting in tetraploidy; this exposure may correlate with the occurrence of tetraploidy in polycystic ovary syndrome and in tumors of the female reproductive tract. The mechanism of dysmorphogenesis involved in polyploidy is considered, including hypotheses of altered nuclear/cytoplasmic ratio, of trophoblastic alteration, of delayed cell division, or of altered autosome/active X chromosome ratio.

Abnormalities, Multiple↗

Further delineation of the G syndrome: a manageable genetic cause of infantile dysphagia.

Three families including five subjects with the G or Opitz-Frias syndrome are added to 23 published cases who had dysphagia; characteristics of the two affected relatives were added to 19 well documented published reports. The data from index cases support the concept of the G syndrome as a constellation of midline defects, which include hypertelorism or telecanthus (89%), oesophageal dysmotility (69%), laryngotracheal clefts (44%), cleft palate or bifid uvula (34%), heart defects (29%), hypospadias (100% of males), renal or ureteral anomalies (42%), and mental retardation (38%). Affected relatives, often identified by hypertelorism, dysphagia, or hypospadias, had a much lower incidence of associated defects and mental retardation. They provide a more rounded but still biased view of a syndrome compatible with normal intelligence and life span. The data do not support a highly characteristic face in the G syndrome, which discriminates it from the phenotypically similar BBB syndrome. The variable expressivity and five cases of male to male transmission observed in 18 families are consistent with autosomal dominant inheritance. Vigilance for the morphological characteristics of G syndrome in patients with dysphagia is underscored by the potential for normal development with appropriate intervention.

Abnormalities, Multiple↗

Effect of aneuploidy and neoplasia on human ribosomal DNA inheritance.

A DNA length polymorphism in the nontranscribed spacer region of the repeating unit that codes for human ribosomal RNA produces a characteristic pattern or restriction fragments in each individual. Quantitative densitometric analysis of ribosomal ribosomal DNA fragment distribution in families demonstrates additive inheritance in those with chromosomally normal or aneuploid offspring. Differences between offspring and parental ribosomal DNA patterns could be explained by a heterogeneous distribution of length variants on the acrocentric chromosomes. New ribosomal DNA length variants of 9.0, 6.7, 5.5, and 5.2 kilobases were observed in normal individuals after BamHI restriction, and the former two were present in multiple copies. A panel of solid tumor specimens exhibited ribosomal DNA patterns that were generally characteristic of the patient rather than tumor type. However, novel ribosomal DNA length variants or changes in length variant proportions were noted in three of the four tumors for which adjacent normal tissue was available for comparison; these alterations occurred in a Burkitt lymphoma, a teratoma, and a Wilms tumor. A consistent karyotype of 50,XY in the Wilms tumor specimen supports previous evidence for increased repetitive DNA variation in aneuploid, neoplastic tissues.

Aneuploidy↗

Cell-specific ribosomal DNA spacer variability in human urothelial carcinoma cultures.

Length variation of a ribosomal DNA "spacer" region in four chromosomally characterized transitional cell carcinoma cultures was analyzed by restriction endonuclease cleavage and Southern blotting. Cell lines with relative karyotypic conservation, such as UM-UC-2 (modal chromosome number 48, four marker chromosomes) demonstrate little change in the genetically regulated pattern of rDNA spacer length polymorphisms (7.6, 6.7 and 6.0 kilobases) which may be found in normal cells. Cell lines with more aberrant karyotypes, such as UM-UC-3 (modal chromosome number 86, 12 marker chromosomes) and UM-UC-4 (modal number 51, ten marker chromosomes) show fewer ribosomal DNA length variants (7.6, 6.7 kilobases for the former, 7.6 kilobases for the latter), consistent with relaxed constraints on the drive for ribosomal gene homogeneity through inter and intrachromosomal exchange. Uncharacterized rDNA length variants of low copy number were observed in cell lines with many marker chromosomes. Analysis of repetitive DNA structure provides an additional criterion for tumor diagnosis and staging, and a characterized series of tumor cell lines may provide a useful system for understanding repetitive DNA evolution.

Carcinoma, Transitional Cell↗