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Biomedical subjects

R F Mueller

Publications and source records attributed to R F Mueller.

At least 55 records · Page 3Linked to original sources
PubMed1997

Selective IgG2 subclass deficiency--a marker for the syndrome of pre/postnatal growth retardation, developmental delay, hypotrophy of distal extremities, dental anomalies and eczema.

We report a third family with members displaying pre- and postnatal growth retardation, hypotonia, psychomotor retardation, small puffy hands and feet, dental anomalies and eczematous skin. The four affected members are all females born to unrelated parents consistent with the previously proposed autosomal recessive mode of inheritance. We report a further clinical feature of selective immunoglobulin IgG2 subclass deficiency which would explain some of the clinical findings and might provide an immunological marker for diagnostic confirmation of the syndrome.

Biomarkers↗
PubMed1996

Linkage studies of non-syndromic recessive deafness (NSRD) in a family originating from the Mirpur region of Pakistan maps DFNB1 centromeric to D13S175.

Autosomal recessive non-syndromal hearing impairment (NSRD) is genetically heterogeneous. Five loci have been identified to date which map to chromosomes 13 (DFNB1), 11 (DFNB2), 17 (DFNB3), 7 (DFNB4) and 14 (DFBN5). We report definite linkage of NSRD to the locus DFNB1 in a single family of 27 families studied of Pakistani origin. Haplotype analysis of markers in the pericentromeric region of chromosome 13q revealed a recombination event which maps DFNB1 proximal to the marker D13S175 and in the vicinity of D13S143.

Child↗
PubMed1996

Human sequences homologous to the gene for the cochlear protein Ocp-II do not map to currently known non-syndromic hearing loss loci.

The abundant and almost exclusive expression of OCP-II protein in the mammalian cochlea has fuelled speculation that mutations in the OCP2 gene may result in inherited forms of hearing impairment. We have identified several human sequences related to OCP2 and sublocalised three of these OCP2 related loci to 4q12-p14 or 4p16.2-pter, 5q15-q21.3 and 7p22-q22 by PCR. 2 YACs with sequence consistent with the chromosome 7 locus were also used for FISH analysis and hybridised to chromosome 7q11. Our data suggest that the cytogenetic localisations of these OCP2 related sequences do not correlate with the precise chromosomal positions of deafness loci so far identified.

Amino Acid Sequence↗
PubMed1996

Characterization of thermophilic consortia from two souring oil reservoirs.

The microbial consortia from produced water at two different oil fields in Alaska (Kuparuk) and the North Sea (Ninian) were investigated for sulfate-reducing and methanogenic activity over a range of temperatures and for a variety of substrates. The consortia were sampled on site, and samples were either incubated on site at 60(deg)C with various substrates or frozen for later incubation and analyses. Temperature influenced the rates of sulfate reduction, hydrogen sulfide production, and substrate oxidation, as well as the cell morphology. The highest rates of sulfate reduction and substrate oxidation were found between 50 and 60(deg)C. Formate and n-butyrate were the most favorable electron donors at any tested temperature. Acetate was utilized at 35(deg)C but not at 50 or 70(deg)C and was produced at 60(deg)C. This indicates that the high levels of acetate found in produced water from souring oil formations are due mainly to an incomplete oxidation of volatile fatty acids to acetate. The cell size distribution of the microbial consortium indicated a nonuniform microbial composition in the original sample from the Kuparuk field. At different temperatures, different microbial morphologies and physiologies were observed. Methane-producing activity at thermophilic temperatures (60(deg)C) was found only for the Kuparuk consortium when hydrogen and carbon dioxide were present. No methane production from acetate was observed. Suppression of methanogenic activity in the presence of sulfate indicated a competition with sulfate-reducing bacteria for hydrogen.

Journal Article↗
PubMed1996

A cross sectional study of renal involvement in tuberous sclerosis.

Renal disease is a frequent manifestation of tuberous sclerosis (TSC) and yet little is known about its true prevalence or natural history. We reviewed the notes of 139 people with TSC, who had presented without renal symptoms, but who had been investigated by renal ultrasound. Information on the frequency, type, and symptomatology of renal involvement was retrieved. The prevalence of renal involvement was 61%. Angiomyolipomas were detected in 49%, renal cysts in 32%, and renal carcinoma in 2.2%. The prevalence of angiomyolipoma was positively correlated with age, compatible with a two hit aetiology. Renal cysts were the commoner lesion in young children, and their prevalence did not appear to be age related. Renal investigation in people with TSC had been inconsistent and limited. We suggest guidelines for renal investigation in those with TSC.

Adolescent↗
PubMed1996

A study of FRAXE in mentally retarded individuals referred for fragile X syndrome (FRAXA) testing in the United Kingdom.

The folate-sensitive fragile site FRAXE is located in proximal Xq28 of the human X chromosome and lies approximately 600 kb distal to the fragile X syndrome (FRAXA) fragile site at Xq27.3. The cytogenetic expression of FRAXE is thought to be associated with mental handicap, but this is usually mild compared to that of the more common fragile X syndrome that is associated with the expression of the FRAXA fragile site. The exact incidence of FRAXE mental retardation is uncertain. We describe here the results of a U.K. survey designed to assess the frequency of FRAXE in a population of individuals referred for fragile X syndrome testing and found to be negative for expansion events at the FRAXA locus. No FRAXE expansion events were found in 362 cytogenetically negative males studied, and one expansion event was identified in a sample of 534 males for whom cytogenetic analyses were either unrecorded or not performed. Further FRAXE expansion events were detected in two related females known to be cytogenetically positive for a fragile site in Xq27.3-28. To gain insight into the FRAXE phenotype, the clinical details of the identified FRAXE male plus three other FRAXE individuals identified through previous referrals for fragile X syndrome testing are presented. For the population studied, we conclude that FRAXE mental retardation is a relatively rare but significant form of mental retardation for which genetic diagnosis would be appropriate.

Base Sequence↗
PubMed1995

Linkage analysis of a large pedigree with hereditary sideroblastic anaemia.

A large pedigree showing a history of pyridoxine responsive X linked sideroblastic anaemia was screened with several polymorphic DNA markers from the X chromosome. Linkage analysis between each marker and disease status was performed, giving a maximum two point lod score of 3.64 at zero recombination with the microsatellite marker PGK1P1 at Xq11.2-12. Close linkage to PGK at Xq13.3, one of the candidate regions for X linked sideroblastic anaemia, was excluded. Linkage to DNA markers distal to PGK and at Xp21 was also excluded. Multipoint linkage analysis was performed with markers located between Xq11.2-21. The maximum map specific lod score obtained was 3.56 at PGK1P1 (Xq11.2-12). Linkage remained significant over the interval 20 cM proximal to PGK1P1 and 5 cM distal to PGK1P1, with definite exclusion around the PGK locus. The most likely location of the gene involved in sideroblastic anaemia in this pedigree is therefore within the pericentromeric region of the X chromosome. This region includes the erythroid 5-aminolaevulinate synthetase gene of the haem synthesis pathway, which is a candidate gene for X linked sideroblastic anaemia located at Xp11.21.

Alleles↗
PubMed1994

Six cases of 7p deletion: clinical, cytogenetic, and molecular studies.

To date, 32 cases of partial 7p monosomy have been described, 14 of which have been associated with craniosynostosis (CRS). There is considerable variation in the size and location of the deleted segment. However, CRS appears to be consistently associated with either a deletion or partial deletion 7p21-->7p22 or more rarely a deletion of 7p13-->7p14. Analysis of a panel of six 7p deletion cases (three with CRS) was undertaken using informative DNA probes, in order to characterize and define the extent of the deletions at the molecular level. There were five de novo deletions and one resulting from the unbalanced product of a paternal balanced insertion. The putative proximal CRS locus at 7p13-->7p14 does not appear to be allelic with Greig cephalopolysyndactyly syndrome. Three probe positions have been refined: pJ5.11 (D7S10) previously mapped to 7p14-->pter does not appear to map proximal to p15; TM102L (D7S135) does not map distal to p22; CRI-P137 (D7S65) maps distal to 7p13.

Chromosome Banding↗
PubMed1994

Automated analysis of multiplex microsatellites.

The use of automated DNA fragment analysis with the Applied Biosystems 672 Genescanner system was evaluated in a routine diagnostic setting. The aim of the study was to compare automated fragment detection and analysis with conventional methods. For cystic fibrosis analysis the delta F508 mutation in exon 10 of the cystic fibrosis transmembrane regulator (CFTR) gene was multiplexed with two intragenic microsatellites. The analysis of the Prader-Willi/Angelman region of chromosome 15 used a panel of five microsatellites. For dystrophin, seven microsatellites covering the entire dystrophin gene were co-amplified. Automated analysis was faster and more accurate than analysis using radiolabelled products with sequencing gels, although some inconsistencies in the sizing of microsatellite alleles were seen.

Angelman Syndrome↗
PubMed1993

Genetic linkage analysis of chromosome 19 markers in malignant hyperthermia.

Previous studies have reported that malignant hyperthermia susceptibility is caused in some families by inherited variation in a gene located on the short arm of chromosome 19 near to, or identical with, the ryanodine receptor gene (RYR1); this is expressed in skeletal muscle as a calcium release channel of the sarcoplasm reticulum. In other families, a gene in this location is excluded, but the locations of the genes involved have not yet been defined. We have analysed DNA samples from members of three large British families in whom in vitro muscle contracture tests for malignant hyperthermia susceptibility have been carried out in accordance with the procedure recommended by the European Malignant Hyperthermia Group. The results presented here strongly suggest that the gene for malignant hyperthermia susceptibility in one or more of these three British families is located in the same region of chromosome 19q, although further work is required to decide whether or not the RYR1 gene itself is causative in these families. As genetic heterogeneity could not be excluded, we cannot yet recommend the use of DNA markers to replace in vitro contracture tests in the diagnosis of malignant hyperthermia susceptibility.

Chromosome Mapping↗
PubMed1992

The 3-M syndrome: risk of intracerebral aneurysm?

We describe a child with typical features of the 3-M syndrome who presented with acute hydrocephalus owing to haemorrhage from one of two intracranial cerebral vascular aneurysms. We suggest that other children with this disorder should be screened for similar complications.

Cerebral Angiography↗