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Biomedical subjects

R R Frants

Publications and source records attributed to R R Frants.

At least 127 records · Page 7Linked to original sources
PubMed1995

A four-generation Dutch family with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), linked to chromosome 19p13.

We describe a four-generation Dutch family suffering from cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Of twenty affected family members, ten are still alive. Age at onset of the strokes was between 29 and 52 years, with a mean of 41.8 years. This family has the typical clinical and radiological features of CADASIL (except for the occurrence of ischemic heart disease at a relatively young age in some subjects), and is linked to chromosome 19p13. This disease has so far been described in families from Finland, France, Germany, Italy, Japan, Spain and the United Kingdom, and there is a remarkable clinical and genetical homogeneity among all families reported, including this Dutch family.

Adult↗
PubMed1995

Homozygotes for CDKN2 (p16) germline mutation in Dutch familial melanoma kindreds.

The p16 gene (CDKN2) which is localized on chromosome 9p21, is deleted in a significant number of sporadic cancers. Moreover, germline mutations identified in some melanoma-prone kindreds last year suggested that CDKN2 is identical to the 9p21-linked melanoma susceptibility gene (MLM); however, failure to identify p16 mutations in all melanoma kindreds putatively linked to 9p21 left some doubts. We have analysed CDKN2 coding sequences in 15 Dutch familial atypical multiple mole-melanoma (FAMMM) syndrome pedigrees, and identified a 19 basepair (bp) germline deletion in 13 of them. All 13 families originate from an endogamous population. The deletion causes a reading frame shift, predicted to result in a severely truncated p16 protein. Interestingly, two family members are homozygous for the deletion, one of whom shows no obvious signs of disease. This surprising finding demonstrates that homozygotes for this CDKN2 mutation are viable, and suggests the presence of a genetic mechanism that can compensate for the functional loss of p16. Our results also greatly strengthen the notion that p16 is indeed MLM.

Amino Acid Sequence↗
PubMed1995

Is familial hemiplegic migraine a hereditary form of basilar migraine?

We studied aura symptoms in 83 patients from 6 unrelated families suffering from familial hemiplegic migraine. Fifty-five of the patients reported symptoms that allowed us to categorize them as basilar migraine (BM) patients, in accordance with the International Headache Society (IHS) criteria. In a control group of 33 patients suffering from migraine with aura and 33 patients suffering from migraine without aura, 9 patients complained of vertigo, and only one patient of diplopia during one of her attacks. None of these control patients fulfilled the IHS criteria for BM. We suggest that familial hemiplegic migraine and BM may share certain pathophysiologic mechanisms, which may consist of a (genetically determined) disturbance of basilar artery blood flow.

Adolescent↗
PubMed1995

Localization of a gene for non-syndromic hearing loss (DFNA5) to chromosome 7p15.

Progressive hearing loss affects approximately 50% of the elderly by the age of 80, and is most likely caused by an interaction of genetic and environmental factors. Identification of the genes responsible for hereditary hearing loss is therefore important. Families with pure genetic degenerative hearing disorders may be helpful as the same genes may be also involved in age-related hearing loss in general. In this study we have performed a genome search in an extended Dutch family with autosomal dominant progressive hearing loss starting in the high frequencies. The gene causing hearing loss in this family was localized to the short arm of chromosome 7, in a 15 cM interval between markers D7S493 and D7S632.

Chromosome Mapping↗
PubMed1995

Inactivation of Apoe and Apoc1 by two consecutive rounds of gene targeting: effects on mRNA expression levels of gene cluster members.

The genes encoding apolipoprotein (apo) E and apoC1 are, together with the gene for apoC2, located in a conserved gene cluster on human chromosome 19q12-13.2 and mouse chromosome 7. Although the significance of apoE as a ligand for receptor-mediated uptake of lipoprotein remnant particles is undisputed, the in vivo function of apoC1 and the possible interaction between apoE and apoC1 in the modulation of plasma cholesterol and triglyceride levels is far from understood. Our strategy to unravel the metabolic relationship between apoE and apoC1 in vivo is to first generate mice deficient in both apolipoproteins, enabling future production of transgenic mice with variable ratios of normal and mutant apoE and apoC1 on a null background. Here we report the creation and characterization of mice deficient in both apoE and apoC1. As these genes are tightly genetically linked, double-deficient mice were obtained by two consecutive rounds of gene targeting in mouse embryonic stem cells. Surprisingly, double inactivation of the Apoe and Apoc1 gene loci as well as single inactivations at either one of these loci were found to affect also the RNA expression levels of the other gene members in the Apoe-c1-c2 cluster. This indicates that targeted insertions are not necessarily neutral for the expression of nearby gene members in a given gene cluster. Homozygous Apoe-c1 knockout mice are hypercholesterolemic, with serum cholesterol levels of 12.5 +/- 4.3 mM compared with 2.9 +/- 0.5 mM in control mice, resembling mice solely deficient in apoE.

Animals↗
PubMed1995

CDKN2 explains part of the clinical phenotype in Dutch familial atypical multiple-mole melanoma (FAMMM) syndrome families.

Combined multi-point linkage analysis in seven Dutch families with FAMMM syndrome confirmed the location of a melanoma susceptibility (MLM) gene in the 9p21 area. The occurrence of a shared high-risk haplotype in six of the families strongly suggests a founder effect in the Leiden region. No indication for locus heterogeneity was observed. Recently, the CDKN2 (p16) gene, an important regulator of the cell cycle, was isolated from the 9p21 region. A 19-bp germline deletion in the CDKN2 gene was detected in the high-risk haplotype, suggesting CDKN2 to be identical to MLM. Loss of heterozygosity studies in melanoma and pancreatic carcinoma from gene carriers strongly support the view that CDKN2 is a general tumour suppressor gene predisposing not only to melanoma but also to other malignancies. Interestingly, the occurrence of apparent clinical FAMMM cases with melanoma but without the high-risk deletion haplotype suggests the necessity of additional (naevus) genes to explain the complete FAMMM phenotype.

Adolescent↗
PubMed1995

Mutations in the low density lipoprotein receptor gene of familial hypercholesterolemic patients detected by denaturing gradient gel electrophoresis and direct sequencing.

Familial hypercholesterolemia (FH) results from mutations in the low density lipoprotein receptor (LDLR) gene. We applied denaturing gradient gel electrophoresis (DGGE) to screen for sequence variations in the coding and splice site consensus sequences of the LDLR gene. For amplification of each exon by the polymerase chain reaction (PCR), optimal pairs of primers were designed by the MELT 87 computer algorithm. To increase the sensitivity, an artificial GC-clamp was included in either the 5'- or the 3'-end of each fragment. DGGE screening of 32 apparently unrelated heterozygous FH patients revealed 16 unique different aberrant DGGE patterns in 27 patients, while in a group of 32 normal subjects none of these DGGE patterns could be observed, suggesting that the aberrant patterns represent disease-causing mutations. Interestingly, 16 out of 27 patients showed an aberrant DGGE pattern in the part of the gene encoding the ligand binding domain (exons 2-6). Direct solid-phase sequencing of the corresponding exon-specific PCR products revealed the nature of the mutations: three nonsense, four splicing, two frameshift, one silent, and six missense mutations. Six of the mutations have been previously reported, while ten are novel mutations. These results indicate that DGGE provides a reliable method for the detection of the presence of point mutations in the LDLR gene of FH patients, thereby facilitating the introduction of rapid DNA diagnosis for this common and genetically heterogeneous disorder.

Base Sequence↗
PubMed1995

Fish mapping of 250 cosmid and 26 YAC clones to chromosome 4 with special emphasis on the FSHD region at 4q35.

Facioscapulohumeral muscular dystrophy (FSHD) is located on chromosome 4q35, close to the telomere. FSHD patients carry deletions within a cluster of tandemly repeated DNA. Although expression of a functional FSHD gene will be altered in patients, the sequence itself may be unaffected by this deletion. Hence, the FSHD gene could lie outside of the deleted region. This study employs fluorescent in situ hybridization using chromosome 4-specific cosmid and YAC clones to rapidly saturate chromosome 4 with new markers. Some 250 cosmids and 26 YACs were regionally mapped, of which 5 YACs and 55 cosmids mapped to the distal portion of 4q. Only one of these clones (D4S1454) mapped telomerically to a translocation breakpoint specified by D4S187. Using two-color interphase mapping, the following marker order was obtained: Cen-D4S187-D4S1454-HSPCAL2-D4S163-D4S139-+ ++D4F35S1. Absence of additional markers mapping distal to D4F35S1 indicates that the linkage group containing the FSHD gene lies extremely close to the 4q telomere.

Cell Line↗
PubMed1995

Search for the FSHD gene using cDNA selection in a region spanning 100 kb on chromosome 4q35.

Facioscapulohumeral muscular dystrophy (FSHD) is caused by deletions of 3.3-kb tandemly repeated units contained within a large polymorphic EcoRI fragment close to the telomere of chromosome 4q. Since the rearrangements were assumed to interfere with the structure or function of the putative FSHD gene, the gene search was focused on cosmids containing these repeat units and, in addition, cosmids spanning 75 kb of upstream sequences. cDNA selection hybridization was applied to four overlapping cosmid clones, yielding a total of 150 putative cDNA clones. These clones showed a random distribution across the cosmid contig, except for three regions which contained a much larger number of clones. Nine cDNA clones hybridized to a 2.2-kb EcoRI fragment, located 22 kb centromeric to the 3.3-kb repeated units. This 2.2-kb fragment showed evolutionary conservation, and analysis of the sequence by "GRAIL" predicted the presence of several exons. Transcripts homologous to this fragment could be identified but none of them originated from the 4q35 locus. Strikingly, most clones revealed 4-10 homologous loci, and no single copy clones could be isolated. These findings are in line with earlier observations by fluorescent in situ hybridization (FISH) showing hybridization of individual cosmid clones to multiple chromosomes. The presence of homologous regions on other chromosomes seriously complicates the cloning of the FSHD gene.

Blotting, Northern↗
PubMed1995

The FSHD-linked locus D4F104S1 (p13E-11) on 4q35 has a homologue on 10qter.

Facioscapulohumeral muscular dystrophy (FSHD) has recently been shown to be associated with deletions that are detectable using probe p13E-11 (D4F104S1). Although these deletions reside within large, highly polymorphic restriction fragments (20-300 kb), the "mutant" fragment is usually shorter than 28 kb and can routinely be detected using conventional agarose gel electrophoresis. Yet, the complete visualization of the alleles requires pulsed-field gel electrophoresis (PFGE). Family studies showed that p13E-11 detects two nonallelic loci in this size range, only one of which originates from chromosome 4q35. We have assigned the other p13E-11 locus to chromosome 10qter by linkage analysis in CEPH pedigrees. Knowing the location of both loci improves the diagnostic reliability, as the exact origin of "small" EcoRI fragments can be determined by haplotyping. Since FSHD shows genetic heterogeneity, this 10qter locus became an interesting candidate to be the second FSHD locus. However, analysis of a large chromosome 4-unlinked FSHD family did not provide evidence for linkage on chromosome 10qter.

Chromosome Mapping↗
PubMed1995

Early onset facioscapulohumeral muscular dystrophy.

We report 10 patients (5 familial, 5 sporadic) with facioscapulohumeral muscular dystrophy (FSHD) with onset of facial and shoulder girdle weakness in early infancy. They showed the same broad range of clinical signs and symptoms as can be seen normally in FSHD. In 7 patients Southern blotting with p13E-11 was performed which showed an abnormal EcoRI fragment (13-22 kb) in 6 of them. We conclude that early onset FSHD does not differ from regular FSHD clinically or genetically. However, the precise mechanisms involved in the extensive clinical variability of the disease are still unknown.

Adolescent↗
PubMed1995

On the significance of retinal vascular disease and hearing loss in facioscapulohumeral muscular dystrophy.

We have performed retinal fluorescein angiography and audiometry in 32 familial and 7 sporadic cases of facioscapulohumeral muscular dystrophy. A mild to moderate retinal vasculopathy, consisting of retinal teleangiectasis and microaneurysms, was present in 18 of 37 evaluable angiograms (49%); 5 patients had minimal changes and 14 angiograms (38%) were normal. High frequency hearing loss was found in 25 (64%) out of 39 patients. Retinal changes were absent in 5 of 18 families (6 cases examined), and after correction for age and sex, hearing function was normal in 5 of 19 families (7 cases examined). Age and severity of the myopathy did not have a clear relationship with the retinal vasculopathy or the hearing loss. There were no differences between families in which the myopathy was linked to chromosome 4q35 and families in which linkage could not be proven. Minimal retinal vascular changes and high tone hearing loss can be observed occasionally in the normal population. Therefore, although retinal vasculopathy and hearing loss are part of the clinical picture of FSHD, these signs cannot be accepted as decisive criteria for FSHD in clinically equivocal cases.

Adult↗
PubMed1995

Facioscapulohumeral muscular dystrophy in the Dutch population.

Extrapolating the figures from a previous study on FSHD in a province of The Netherlands to the entire Dutch population suggests that at present a nearly complete overview is obtained of all symptomatic kindred. In 139 families, dominant inheritance was observed in 97, a pattern compatible with germline mosaicism in 6, while sporadic cases were found in 36 families. A mutation frequency of 9.6% was calculated. Mental retardation and severe retinal vasculopathy were reported in low frequencies (1%). Early onset was seen more frequently in sporadic cases. Chromosome 4 linkage appeared excluded in 3 of 22 autosomal-dominant families. The clinical pictures in the linked and nonlinked families were identical.

Age of Onset↗
PubMed1994

Linkage of autosomal dominant hearing loss to the short arm of chromosome 1 in two families.

BACKGROUND: At least half of the cases of profound deafness of early onset are caused by genetic factors, but few of the genetic defects have been identified. This is particularly true of the most common hereditary forms of deafness, which occur in the absence of any associated syndrome. METHODS: We studied a large Indonesian family in which hearing loss was inherited in an autosomal dominant pattern. The hearing loss first affects the high frequencies during the teens or 20s and becomes profound within 10 years. To locate the responsible gene, we performed genetic-linkage analysis, using microsatellite markers distributed over the entire genome. We then performed linkage analyses in an American family and a Dutch family with similar patterns of hereditary hearing loss. RESULTS: In the extended Indonesian family, a gene linked to deafness mapped to chromosome 1p, with a multipoint lod score of more than 7. In the American family, deafness was linked to the same locus on chromosome 1p, with a multipoint lod score of more than 5. In the Dutch family, however, this locus was ruled out. The flanking markers D1S255 and D1S211 defined a region of 6 cM on chromosome 1p that is likely to contain the gene associated with deafness in the first two families. CONCLUSIONS: In some families with early-onset autosomal dominant hearing loss, the responsible gene is on chromosome 1p.

Adolescent↗
PubMed1994

Genetic heterogeneity of familial hemiplegic migraine.

Familial hemiplegic migraine (FHM) is a distinctive form of migraine with an autosomal dominant mode of inheritance. The migraine-like attacks are associated with transient hemiparesis. A locus for FHM has recently been assigned to chromosome 19 by linkage mapping. In the present study, five unrelated pedigrees with multiple members suffering from hemiplegic migraine were investigated. In two of the pedigrees additional symptoms, cerebellar ataxia and benign neonatal convulsions, respectively, were observed in affected members. Three pedigrees showed linkage to loci D19S391, D19S221, and D19S226 at chromosome 19p13. Haplotyping suggested a location of a FHM gene between D19S391 and D19S221. In the two remaining families, evidence against linkage was found. These results confirm the localization of a gene for familial hemiplegic migraine to the short arm of chromosome 19, but locus heterogeneity not corresponding to the observed clinical heterogeneity is likely to exist.

Chromosome Mapping↗
PubMed1994

The apolipoprotein C2-linked (Acl) gene: a new gene within the mouse apolipoprotein e-c1-c2 gene cluster.

The apolipoprotein E, C1, and C2 genes are contained within a gene cluster in man. Previously, we have shown that this gene cluster has a similar structure in mouse. During the characterization of the mouse Apoc2 gene, evolutionarily conserved and transcribed sequences were found 5' of the Apoc2 gene. In this study, we have shown that these 5' sequences represent a novel gene within the gene cluster designated the apolipoprotein C2-linked gene (Acl). The Acl gene is located 2 kb 5' to the Apoc2 gene. The transcriptional orientation is identical to that of the other genes within the Apoe-c1-c2 gene cluster. We have sequenced the mouse Acl gene at the cDNA and the genomic levels. The gene is composed of three exons spanning a region of approximately 3.6 kb. The Acl gene is expressed in the liver as a transcript 473 bp in size and encodes a putative protein of 124 amino acid residues.

Amino Acid Sequence↗
PubMed1994

Pulsed-field gel electrophoresis of the D4F104S1 locus reveals the size and the parental origin of the facioscapulohumeral muscular dystrophy (FSHD)-associated deletions.

Recently, probe p13E-11 (D4F104S1) was shown to identify de novo DNA rearrangements, which are associated with the development of facioscapulohumeral muscular dystrophy (FSHD). These rearrangements are likely to become instrumental in cloning the FSHD gene itself. Analysis by pulsed-field gel electrophoresis demonstrates that p13E-11 recognizes two highly polymorphic loci, with HindIII restriction fragments ranging in size from about 30 to 320 kb. Haplotype analysis unambiguously assigned one of the two loci to chromosome 4q35. The detection of identical NotI or NruI fragments with both CEB8 (D4F35S1) and p13E-11 demonstrated that the DNA rearrangements are deletions that are restricted to the HindIII fragments detectable by p13E-11. In two cases, the sizes of the deletion could be established and were found to be 25 and 85 kb in length, respectively. So far, we have been able to define the parental origin of the mutation in seven different patients and have found that in five cases the maternal allele was involved.

Chromosomes, Human, Pair 4↗