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Biomedical subjects

H Scheffer

Publications and source records attributed to H Scheffer.

At least 73 records · Page 4Linked to original sources
PubMed1995

A sublocus of the multicopy microsatellite marker CMS1 maps proximal to spinal muscular atrophy (SMA) as shown by recombinant analysis.

The critical region containing the spinal muscular atrophy (SMA) gene is flanked by the 5q11-q13 markers, D5S435 and D5S557, as determined by linkage analysis. Here we present the results of an analysis of a Dutch SMA family with the multicopy microsatellite marker CMS1. A crossover is revealed in the critical SMA region. We conclude that at least one of the CMS1 subloci maps proximal to the SMA gene. This reduces the minimal SMA region from approximately 1.4 Mb to 600-700 kb.

Chromosome Mapping↗
PubMed1995

Refinement by linkage analysis in two large families of the candidate region of the third locus (SCA3) for autosomal dominant cerebellar ataxia type I.

The autosomal dominant cerebellar ataxias (ADCA) are clinically and genetically heterogeneous. To date, several loci (SCAI-V) have been identified for ADCA type I. We have studied two large families from the northern part of The Netherlands with ADCA type I with a broad intra-familial variation of symptoms. In both families significant linkage is shown of the disease to the markers of the SCA3 locus on chromosome 14. Through recombinations, the candidate region for SCA3 could be refined to a 13-cM range between D14S256 and D14S81. No recombinations were detected with the markers D14S291 and D14S280, which suggests that the SCA3 gene lies close to these loci. This finding will benefit the individuals at risk in these two families who are seeking predictive testing or prenatal diagnosis.

Adult↗
PubMed1995

Hereditary myokymia and paroxysmal ataxia linked to chromosome 12 is responsive to acetazolamide.

A sixth family with autosomal dominantly inherited myokymia and paroxysmal ataxia is described. The syndrome in this family is linked to the recently discovered locus for inherited myokymia and paroxysmal ataxia on the human chromosome 12p, and a missense mutation is shown in the KCNA1 gene. The attacks of ataxia in this family compare well with those of previously described families and similarly are precipitated by kinesigenic stimuli, exertion, and startle. Responsiveness of these attacks to low dose acetazolamide is confirmed, but some loss of efficacy occurs with prolonged treatment, and side effects are notable. Although not all affected family members showed myokymia on clinical examination, electromyography invariably showed myokymic discharges, in one patient only after a short provocation with regional ischaemia. One affected family member also had attacks of paroxysmal kinesigenic choreoathetosis, responsive to carbamazepine.

Acetazolamide↗
PubMed1995

A provisional transcript map of the spinal muscular atrophy (SMA) critical region.

YACs from the region containing the spinal muscular atrophy (SMA) locus at 5q12 have been used as probes in a direct screening of cDNA libraries to isolate 8 cDNAs, mapped to different YAC fragments. Three clones showed complete identity to the genes for cyclin B1 (CCNB1), the p44 subunit of the transcription factor BTF2 (BTF2p44), and cofilin (CFL). Two clones showed partial identity to the beta-glucuronidase gene (GLCB) and a rat integral membrane glycoprotein gene (RNINMEGLA). CFL turned out to have been identified by a pseudogene sequence. Related sequences occurred on other chromosomes. CCNB1 and BTF2p44 were given an exact location. The GLCB-like gene and the RNINMEGLA-like gene detected loci on both 5q and 5p. The remaining three cDNA clones were localized to the SMA region only. Their sequences did not show identity to any gene for which a function is already known. Two of them have now turned out to be identical to recently reported candidate genes for SMA.

Actin Depolymerizing Factors↗
PubMed1995

An integrated map of human chromosome 13 allowing regional localization of genetic markers.

37 CA repeats, 5 STSs, 9 ESTs, and 4 genes were mapped to 19 different intervals of chromosome 13 determined by the cytogenetic breakpoints of 19 different cell lines with interstitial deletions or translocations involving various parts of chromosome 13. A framework genetic linkage map was constructed from 25 of these microsatellite markers, to which 26 markers from other genetic maps were added. Thus, an integrated map of chromosome 13 resulted. Since the microsatellite markers included in this study derive from different genetic maps, an approximate regional localization can now be assigned in principle to any genetic marker on chromosome 13.

Animals↗
PubMed1995

Deletions of the survival motor neuron gene in unaffected siblings of patients with spinal muscular atrophy.

DNA studies in 103 spinal muscular atrophy (SMA) patients from The Netherlands revealed homozygosity for a survival motor neuron (SMN) deletion in 96 (93%) of 103. Neuronal apoptosis inhibitory protein deletions were found in 38 (37%) of 103 and occurred most frequently in SMA type I. SMN deletions have not yet been described to occur in healthy subjects. In this study, however, four unaffected sibs from two SMA families showed homozygosity for SMN deletions. Homozygosity for an SMN deletion in unaffected persons seems to be very rare. Therefore, demonstration of a homozygous SMN deletion in a clinically presumed SMA patient should be considered as a confirmation of the diagnosis, whether or not SMN is in fact the causal gene for SMA.

DNA↗
PubMed1994

Identification of key recombinants in multiplex SMA families.

Recent reports have provided evidence that a major gene for autosomal recessive proximal spinal muscular atrophy (SMA) resides in a small genetic interval in bands q12-q13 of chromosome 5, a 4-cM region proximally flanked by D5S125 (EF(TG/AG)n) and distally by MAP1B/D5S112 or a 0.7-cM interval (range 0.1-2.1 cM) flanked by D5S435 proximally and MAP1B/D5S112 distally. We present the identification of key recombinants between SMA and the closest flanking DNA-markers in an analysis of Dutch and Italian SMA families. These crossovers may serve as reference points for new markers in this region and may thus be instrumental in a further refined mapping of the SMA gene. Two markers, D5S351 (I105) and D5S357 (Mfd151), could be mapped distally to SMA in the interval SMA-D5S112.

Chromosome Mapping↗
PubMed1994

A giant congenital orbital tumor: an unusual presentation of retinoblastoma.

We report a case of an unusual giant congenital tumor presenting in a newborn infant as a large exophytic mass emerging from the left orbit. After enucleation orbital recurrence developed within 14 days. No anti-tumor treatment was given and the child died at the age of 4 weeks. The histopathological and cytogenetical analysis of the tumor is presented. The tumor was diagnosed as a retinoblastoma but we could not exclude the possibility of a neuroblastoma.

Eye Neoplasms↗
PubMed1994

Apparent SMA I unlinked to 5q.

A proband with a clinical picture indistinguishable from SMA type I is described. The parents are second cousins. On DNA analysis it appeared that the proband and his healthy 2 year old sib had inherited the same haplotypes for DNA markers flanking the SMA locus on 5q. This supports non-linkage of SMA to chromosome 5q in this family. The consanguinity of the parents raises the possibility of a second locus for autosomal recessive SMA type I outside the 5q12-13 region. This may have implications for genetic counselling after prenatal diagnosis in consanguineous families. Furthermore, this case illustrates the importance of the inclusion of all healthy sibs in prenatal DNA studies for SMA type I.

Chromosomes, Human, Pair 5↗
PubMed1994

A deletion hybrid breakpoint map of the chromosomal region 13q14-q21 orders 19 genetic markers in 10 intervals.

A deletion hybrid breakpoint map of the chromosomal region 13q14-q21 has been constructed using 19 DNA markers and 13 cell lines with breakpoints in this chromosomal region. The cell lines define 10 distinct intervals in this region, which spans approximately 20 Mb. The markers include 6 RFLP markers, 11 microsatellites that provisionally had been mapped to the region 13q14-21, and 2 new polymorphic CA-repeats that were developed from an EMBL3 library of cell line ICD, containing 13pter-q14.3. The following order of markers was established: CEN-D13S320-(D13S118, D13S153)-RB1-D13S319-D13S25-(D13S31, D13S59, D13S133, D13S137)-D13S163-D13S119-(D13S26, D13S55)-(D13S131, D13S134, D13S135, D13S144, D13S152)-TEL.

Base Sequence↗
PubMed1994

Tissue kallikrein activity and kinin release in human endothelial cells.

The kininogenase, tissue kallikrein (EC 3.4.21.8), has been identified in different blood vessels. The enzyme was mainly found in vascular smooth muscle cells. It is not known whether it is present and functionally active in vascular endothelial cells. The following study investigates the presence of tissue kallikrein in endothelial cells from human umbilical veins and pulmonary arteries. Tissue kallikrein was demonstrated in three ways: 1) by immunostaining in endothelial cells; 2) by measurement of tissue kallikrein activity using a colorimetric assay; 3) by the measurement of kinin release in intact and homogenised endothelial cells with a radioimmunoassay. Immunostaining demonstrated the presence of tissue kallikrein in endothelial cells from human umbilical veins and endothelial cells from human pulmonary arteries. Tissue kallikrein-like activity, measured by the degradation of D-Val-cyclohexyl-Ala-Arg-4-nitraniline, was 3.57 +/- 0.5 mU/10(6) endothelial cells from human umbilical veins and 7.52 +/- 0.84 mU/10(6) endothelial cells from human pulmonary arteries. Intracellular kinin concentrations were 424 +/- 83 pg/10(6) cells in endothelial cells from human umbilical veins and 576 +/- 146 pg/10(6) cells in endothelial cells from human pulmonary arteries, and they increased in a time-dependent manner after homogenisation. The increase was abolished by aprotinin (1000 kIU), an inhibitor of tissue kallikrein in both cell types. Addition of exogenous kallikrein (5 mU) to homogenised cells led to a five fold increase of kinin concentrations after five minutes, indicating a sufficient resource of cellular kininogen. Removal of extracellularly bound kininogen by washing with dextran sulphate (100 mg/l) resulted in an approximately 75% reduction of the cellular kinin release.(ABSTRACT TRUNCATED AT 250 WORDS)

Cells, Cultured↗
PubMed1993

Physical localisation of the chromosomal marker D13S31 places the Wilson disease locus at the junction of bands q14.3 and q21.1 of chromosome 13.

D13S31 is the marker closest to the Wilson disease locus according to genetic analysis. Its physical localisation was refined by fluorescent in situ hybridisation to the junction to chromosomal bands 13q14.3 and 13q21.1. Using polymerase chain reaction analysis, D13S31 and D13S59 (the closest proximal and distal marker, respectively) were found to be located on the end of the der(13) consisting of 13pter-13q14.3: in the somatic cell hybrid ICD, and to be absent from the cell lines WC-H38B3B6 containing a del(13) (13pter-q13::13q21.1-qter) and KSF39 containing a del(13) (13pter-q14.1:).

Animals↗
PubMed1993

Linkage and apparent heterogeneity in proximal spinal muscular atrophies.

Linkage studies with 9 highly informative DNA markers on the long arm of chromosome 5 were performed in 12 multiplex families (29 patients) with spinal muscular atrophy (SMA) from The Netherlands. The results of the linkage analysis were compatible with localization of a major SMA gene in the chromosomal region 5q12-13. By minimum recombinant analysis the most likely position of the SMA locus was between loci D5S6/D5S125 and D5S112/MAP1B, which is in agreement with several linkage studies from other countries. In four families, however, more than one crossover between SMA and a flanking DNA marker appeared, and in one family the observed hybridization phenotype for the markers closely flanking the SMA locus was identical for an unaffected individual and for his two affected sibs with SMA type III. For this latter family, among several explanations the most likely are either the presence of a double crossover or linkage heterogeneity.

Chromosome Mapping↗