Biomedical subjects
S B Dowton
Publications and source records attributed to S B Dowton.
Vertebral anomalies in a new family with ODED syndrome.
We report a new family with oculodigitoesophagoduodenal syndrome (ODED syndrome), which associates microcephaly, abnormalities of the hands and feet, shortened palpebral fissures, tracheoesophageal fistula and duodenal atresia. In addition, previously unreported vertebral anomalies are described. This report further delineates the clinical and radiographic spectrum of this syndrome, providing useful information for diagnosis and family counseling.
Partial monosomy of distal 10q: three new cases and a review.
We report on 3 patients with partial deletions of the long arm of chromosome 10-46,XY,del (10)(q26.2), 46,XX,del(10) (q25.3q26.3) or 46,XX,del(10)(q26.1), and 46,XX,del (10)(q26.1). They are compared with other known cases with interstitial or terminal deletions involving chromosome bands 10q25 or q26. Unique manifestations are identified, including scoliosis and a severe behavior disorder with attention deficit and hyperactivity in a 12-year-old boy as well as patchy alopecia in a 6-year-old patient.
Deletion of 1q in a patient with acrofacial dysostosis.
The Nager syndrome is the most common form of acrofacial dysostosis. Although autosomal dominant and recessive forms of acrofacial dysostosis have been described the molecular etiology of these disorders is unknown. We report on a child with acrofacial dysostosis, critical aortic stenosis, and a deletion of chromosome 1q involving the heterochromatic block and adjacent euchromatin.
Methylmalonic aciduria (cblF): case report and response to therapy.
Methylmalonic acidemia can be secondary to a deficiency of methylmalonyl CoA mutase or to a defect of cobalamin metabolism that is classified by complementation group. We report on a new patient with cblF complementation group that is associated with an elevation of both methylmalonic acid and homocysteine, and her outcome in response to routine therapy and a dietary restriction.
Unique cardiac and cerebral anomalies with chondrodysplasia punctata.
Chondrodysplasia punctata (CDP) is associated with a variety of genetic and nongenetic conditions. We report a girl with CDP, complex congenital cardiac disease, central nervous system (CNS) anomalies, and clinical findings that resemble those of the sibs described by Toriello et al. [1993, Am J Med Genet 47:797-799]. The cardiac defects and CNS abnormalities reported are unique in the context of CDP and may serve to expand the phenotypic spectrum of the unique form of CDP described by Toriello et al. [1993].
Serum amyloid A gene expression in rabbit, mink and mouse.
The expression of serum amyloid A (SAA) protein, a major acute-phase reactant in most species, was examined by in situ hybridization in multiple organs of rabbit, mink and mouse. In livers of unstimulated mice and rabbits a heterogeneous pattern of SAA expression in hepatocytes was observed. In all three species, lipopolysaccharide (LPS) administration resulted in extensive uniform hybridization of SAA probes to hepatocytes and in the rabbit SAA transcripts were detected in cells in the white pulp of the spleen, the adrenal cortex and ovary as well as in the mucosa and lymphatic vessels of the small intestine. Examination of hybridizing SAA signals in the rabbit myocardium showed a speckled distribution in myocytes. The rabbit endocardium was strongly positive, and in the kidney rabbit SAA mRNA was mainly confined to epithelial cells of the proximal and distal convoluted tubules. In the unstimulated mouse, SAA mRNA was detected in the liver and epithelial cells of the small and large intestine. After stimulation of an acute-phase response with LPS a strong response was seen in these organs as well as in the convoluted tubules of the kidney. In extrahepatic organs of the mink, no SAA mRNA was detectable in unstimulated animals, while the convoluted tubules of the kidney and uterine endometrium were strongly positive after systemic LPS injection.
Chromosome 18q22.2-->qter deletion and a congenital anomaly syndrome with multiple vertebral segmentation defects.
Multiple vertebral segmentation defects occur in a group of conditions variably associated with anomalies of other organ systems. This report describes a female child in whom a deletion of chromosome 18 (18q22.2-->qter) is associated with congenital anomalies including multiple vertebral segmentation defects resembling sporadic spondylocostal dysplasia. The child also has unilateral renal agenesis and unilateral fibular aplasia. The association of severe multiple vertebral segmentation defects with 18q- in this patient suggests the possibility that a gene important for somite formation or vertebral differentiation maps to this segment of chromosome 18.
Need for velopharyngeal management following palatoplasty: an outcome analysis of syndromic and nonsyndromic patients with Robin sequence.
The Robin sequence is a pathogenetically and etiologically heterogeneous condition that can be a nonsyndromic anomaly or one feature of many syndromes. Little information is available regarding the distribution of patients having Robin sequence, with or without associated syndromes, who develop velopharyngeal dysfunction. In order to discern whether patients with Robin sequence, nonsyndromic and/or syndromic, have different velopharyngeal dysfunction rates from those observed among all patients undergoing palatoplasty during the same time period, a retrospective study was undertaken. The charts of 873 patients with overt clefts of the secondary palate managed at a single cleft center between 1978 and 1992 were reviewed. Diagnostic criteria for Robin sequence included cleft palate without cleft lip, microretrognathia, and perinatal respiratory and/or feeding difficulties; 79 such patients (9 percent) were identified from the initial group of 873. Of these, 58 patients (7 percent) were at least 3 years of age and had sufficient follow-up to allow for evaluation of speech outcome by an experienced speech pathologist through a variety of methodologies (videonasendoscopy, speech videofluoroscopy, perceptual speech characteristics). This group comprised the Robin sequence study population. All Robin sequence patients' charts were reviewed by a medical geneticist to confirm the presence or absence of a syndrome. Of the original 873 patients, there were 127 non-Robin sequence patients who were sufficiently cooperative in diagnostic testing to yield definitive information. This group comprised the non-Robin sequence study population. Among nonsyndromic Robin sequence patients, 15 of 34 (44 percent) developed velopharyngeal dysfunction and required velopharyngeal management, while 2 of 24 syndromic patients (8 percent) developed velopharyngeal dysfunction (p = 0.003). Of the 127 non-Robin sequence isolated cleft palate patients, 113 were nonsyndromic, of whom 18 percent (20 of 113) required velopharyngeal dysfunction management, and 14 were syndromic, of whom 64 percent (9 of 14) required velopharyngeal dysfunction management (p = 0.00009). We conclude that nonsyndromic Robin sequence patients have a higher rate of postpalatoplasty velopharyngeal dysfunction than the nonsyndromic non-Robin sequence cleft population. Outcome analysis of velopharyngeal function in cleft patients should take into account patients who have cleft palate in association with Robin sequence, with or without a recognizable syndrome.
Linkage of a familial platelet disorder with a propensity to develop myeloid malignancies to human chromosome 21q22.1-22.2.
Linkage analysis was performed on a large pedigree with an autosomal dominant platelet disorder and a striking propensity in affected family members to develop hematologic malignancy, predominantly acute myelogenous leukemia. We report the linkage of the autosomal dominant platelet disorder to markers on chromosome 21q22. Four genetic markers completely cosegregate with the trait and yield maximum logarithm of difference scores ranging from 4.9 to 10.5 (theta = .001). Two flanking markers, D21S1265 and D21S167, define a critical region for the disease locus of 15.2 centimorgan. Further analysis of this locus may identify a gene product that affects platelet production and function and contributes to the molecular evolution of hematologic malignancy.
A novel missense mutation in the exon containing the putative ornithine-binding domain of the OTC enzyme in a female.
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Nonketotic hyperglycinemia: atypical clinical and biochemical manifestations.
A 16-year-old boy had intermittent chorea, delirium, and vertical gaze palsy precipitated by febrile illness. Nonketotic hyperglycinemia was confirmed by measurement of liver and lymphoblast glycine cleavage enzyme activity. Deficient but residual enzyme activity was demonstrated in both tissues, possibly accounting for the mild phenotype. Confirmation of an atypical variant of nonketotic hyperglycinemia with residual glycine cleavage enzyme activity has important implications for diagnosis and treatment.
Grouped papules in Hurler-Scheie syndrome.
In a patient with Hurler-Scheie syndrome, a type of mucopolysaccharidosis (I H/S), an initial presentation was grouped papules on the extensor surfaces on the upper portions of the arms and legs. Other physical findings included progressive flexion contractures and mild developmental delay. The patient had deficient alpha-L-induronidase activity, and electron microscopy showed large cytoplasmic vacuoles and lysosomes, consistent with Hurler-Scheie syndrome. Findings of grouped papules have not been previously reported in patients with this syndrome.
Respiratory complications of Ehlers-Danlos syndrome type IV.
Pulmonary complications are described in a case of Ehlers-Danlos syndrome type IV, established by studies of collagen biosynthesis. At age 20.5 years the patient, who had previously suffered a spontaneous colonic perforation, developed intermittent recurrent hemoptysis and had a spontaneous hemopneumothorax. At presentation, imaging studies revealed multiple scattered cavitary lesions in both lungs. On separate occasions large parenchymal cysts ensued and subsequently regressed. Reviews of other reported patients indicate that pulmonary complications do occur in patients with Ehlers-Danlos syndrome type IV but have not resulted directly in patient mortality.
Linkage of preaxial polydactyly type 2 to 7q36.
We have characterized a 6-generation North American Caucasian kindred segregating one form of preaxial polydactyly type 2 (PPD-2). We demonstrate linkage to the 7q36 region and describe a submicroscopic telomeric chromosomal deletion in phase with the PPD-2 phenotype. Recently, several kindreds segregating triphalangeal thumb (TPT) with and without associated hand anomalies (syndactyly and/or postaxial polydactyly) have also been linked to the subtelomeric region of chromosome 7q [Heutink et al., 1994: Nat Genet 6:287-291; Tsukurov et al., 1994: Nat Genet 6:282-286]. We demonstrate by haplotype analysis that our North American pedigree represents a PPD allele that is independent of the founder PPD allele present in the previously described kindreds.
Deletion within chromosome 22 is common in patients with absent pulmonary valve syndrome.
Interstitial deletions in chromosome 22 and features associated with CATCH-22 syndrome have been reported in patients with conotruncal congenital heart anomalies. Absent pulmonary valve syndrome is characterized by absent or rudimentary pulmonary valve cusps, absent ductus arteriosus, conoventricular septal defect, and massive dilation of the pulmonary arteries. Because absence of the ductus arteriosus is a key element in the pathogenesis of this syndrome and aortic arch malformations are frequently seen in patients with CATCH-22 syndrome, we hypothesized that patients with absent pulmonary valve syndrome would have a high incidence of deletions in the critical region of chromosome 22. Eight patients with absent pulmonary valve syndrome were studied. Metaphase preparations were examined with fluorescent in situ hybridization of the N25 (D22S75) probe to the critical region of chromosome 22q11.2. Deletions were detected in 6 of 8 patients. The presence of deletions in chromosome 22 in most of the patients we have examined with a diagnosis of absent pulmonary valve syndrome supports a specific genetic and embryologic mechanism involving the interaction of the neural crest and the primitive aortic arches as one cause of congenital absence of the pulmonary valve.
Diagnosis of human heritable diseases--laboratory approaches and outcomes.
Detection of mutant human genes is rapidly becoming an integral part of clinical practice. Human disease may arise by genetic deletion, insertion, fusion, point mutation, or amplification of unstable sequences. Such changes in structure may occur in germ cells or somatically. Rapid advances in understanding the complex nuclear and mitochondrial genomes necessitates deployment of a variety of methods to identify aberrant genes. These techniques include polymerase chain reaction, Southern transfer, and allele-specific hybridization studies, as well as methods to unmask mismatches between mutant and normal sequences. Development of protein truncation tests has added a vehicle for assessing larger DNA segments for mutations that cause premature translational termination. Linkage analysis remains an important tool where direct assay of disease-causing mutations is not possible. Considerations of confidentiality, informed consent, and insurability are important whenever genetic testing is used. These issues will assume increasing importance as presymptomatic testing for heritable predispositions emerges for common conditions.
Serum amyloid A: an acute phase apolipoprotein and precursor of AA amyloid.
Serum amyloid A is an acute phase protein complexed to HDL as an apoprotein. The molecular weight is 11.4-12.5 kDa in different species and the protein has from 104 to 112 amino acids, without or with an insertion of eight amino acids at position 72. The protein is very well conserved throughout evolution, indicating an important biological function. The N-terminal part of the molecule is hydrophobic and probably responsible for the lipid binding properties. The most conserved part is from position 38 to 52 and this part is therefore believed to be responsible for the until now unknown biological function. The protein is coded on chromosome 11p in man, and chromosome 7 in mice, and found in all mammals until now investigated, and also in the Peking duck. In the rat a truncated SAA mRNA has been demonstrated, but no equivalent serum protein has been reported. Acute phase SAA is first of all produced in hepatocytes after induction by cytokines, but extrahepatic expression of both acute phase and constitutive SAA proteins have been demonstrated. Several cytokines, first of all IL-1, IL-6 and TNF are involved in the induction of SAA synthesis, but the mutual importance of these cytokines seems to be cell-type specific and to vary in various experimental settings. The role of corticosteroids in SAA induction is somewhat confusing. In most in vitro studies corticosteroids show an enhancing or synergistic effect with cytokines on SAA production in cultured cell. However, in clinical studies and in vivo studies in animals an inhibitory effect of corticosteroids is evident, probably due to the all over anti-inflammatory effect of the drug. Until now no drug has been found that selectively inhibits SAA production by hepatocytes. Effective anti-inflammatory or antibacterial treatment is the only tool for reducing SAA concentration in serum and reducing the risk of developing secondary amyloidosis. The function of SAA is still unclear. Interesting theories, based on current knowledge of the lipid binding properties of the protein and the relation to macrophages, in the transportation of cholesterol from damaged tissues has been advanced. A putative role in cholesterol metabolism is supported by the findings of SAA as an inhibitor of LCAT. The potential that SAA is a modifying protein in inflammation influencing the function of neutrophils and platelets is interesting and more directly related to the inflammatory process itself.(ABSTRACT TRUNCATED AT 400 WORDS)