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P F Chance

Publications and source records attributed to P F Chance.

At least 73 records · Page 4Linked to original sources
PubMed1994

Inherited neuropathies: Charcot-Marie-Tooth disease and related disorders.

Collectively, the inherited disorders of peripheral nerves represent a common group of neurological diseases and are frequently encountered in the clinical setting. Recent advances in molecular genetics have not only provided improved diagnosis and counselling, but may ultimately lead to specific, rational therapies for the various forms of inherited neuropathy. Charcot-Marie-Tooth neuropathy type 1 (CMT1) is a genetically heterogeneous group of chronic demyelinating polyneuropathies with loci mapping to chromosome 17p (CMT1A), chromosome 1q (CMT1B), the X chromosome (CMTX) and to another unknown autosome (CMT1C). CMT1A is most often associated with a tandem 1.5-megabase (Mb) duplication in chromosome 17p11.2-12, or may occasionally result from a point mutation in the peripheral myelin protein 22 (PMP22) gene. CMT1B is associated with point mutations in the myelin protein zero (P0) gene. The molecular defect in CMT1C is unknown. CMTX is associated with defects in the connexin 32 gene. Charcot-Marie-Tooth neuropathy type 2 (CMT2) is an axonal neuropathy, also of undetermined cause. One locus for CMT2 has been assigned for chromosome 1p (CMT2A). Dejerine-Sottas disease is a severe, infantile-onset, demyelinating polyneuropathy which may be associated with point mutations in the P0 or PMP22 genes. Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal dominant disorder that results in a recurrent, episodic demyelinating neuropathy. HNPP is associated with a 1.5-Mb deletion in chromosome 17p11.2-12 and may result from reduced expression of the PMP22 gene. CMT1A and HNPP are apparent reciprocal duplication/deletion syndromes originating from unequal cross-over during germ-cell meiosis.

Charcot-Marie-Tooth Disease↗
PubMed1994

Refined genetic mapping of X-linked Charcot-Marie-Tooth neuropathy.

Genetic linkage studies were conducted in four multigenerational families with X-linked Charcot-Marie-Tooth disease (CMTX), using 12 highly polymorphic short-tandem-repeat markers for the pericentromeric region of the X chromosome. Pairwise linkage analysis with individual markers confirmed tight linkage of CMTX to the pericentromeric region in each family. Multipoint analyses strongly support the order DXS337-CMTX-DXS441-(DXS56,PGK1).

Adult↗
PubMed1993

Connexin mutations in X-linked Charcot-Marie-Tooth disease.

X-linked Charcot-Marie-Tooth disease (CMTX) is a form of hereditary neuropathy with demyelination. Recently, this disorder was mapped to chromosome Xq13.1. The gene for the gap junction protein connexin32 is located in the same chromosomal segment, which led to its consideration as a candidate gene for CMTX. With the use of Northern (RNA) blot and immunohistochemistry technique, it was found that connexin32 is normally expressed in myelinated peripheral nerve. Direct sequencing of the connexin32 gene showed seven different mutations in affected persons from eight CMTX families. These findings, a demonstration of inherited defects in a gap junction protein, suggest that connexin32 plays an important role in peripheral nerve.

Amino Acid Sequence↗
PubMed1993

DNA deletion associated with hereditary neuropathy with liability to pressure palsies.

Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal dominant disorder that causes episodes of focal demyelinating neuropathy following minor trauma to peripheral nerves. We assign the HNPP locus to chromosome 17p11.2 and demonstrate the presence of a large interstitial deletion associated with this disorder in three unrelated pedigrees. De novo deletion is documented in one pedigree. The deleted region appears uniform in all pedigrees and includes the gene for peripheral myelin protein 22 (PMP-22), suggesting that underexpression of PMP-22 may cause HNPP. The deletion in HNPP spans approximately 1.5 Mb and includes all markers that are known to map within the Charcot-Marie-Tooth neuropathy type 1A (CMT1A) duplication. Furthermore, the breakpoints in HNPP and CMT1A map to the same intervals in 17p11.2, suggesting that these genetic disorders may be the result of reciprocal products of unequal crossover.

Chromosome Mapping↗
PubMed1993

Charcot-Marie-Tooth syndrome.

Charcot-Marie-Tooth syndrome (CMT) is a group of genetically determined symmetric distal polyneuropathies. The CMT loci are known to map to chromosome 1 (CMT1B), chromosome 17 (CMT1A), the X chromosome (CMTX), and two additional unknown autosomes (CMT1C and CMT2). The most prevalent form is CMT1A, an autosomal dominant demyelinative disorder caused either by a tandem duplication in band p11.2-12 of chromosome 17 (17p11.2-12) with trisomic expression of the peripheral myelin protein-22 (PMP-22) gene or, less frequently, by a missense mutation of PMP-22. Missense mutations in PMP-22 are also responsible for two forms of demyelinative polyneuropathy in mice, trembler and trembler. Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal dominant disorder characterized by recurrent focal neuropathy. In all families thus far studied, patients with HNPP have been found to be monosomic for a segment of chromosome 17p11.2-12. The duplication in CMT1A and deletion in HNPP map to the same region in 17p11.2-12 and are both likely to be consequences of unequal crossing over during germ cell meiosis.

Animals↗
PubMed1993

Charcot-Marie-Tooth neuropathy type 1B is associated with mutations of the myelin P0 gene.

P0, a major structural protein of peripheral myelin, is a homophilic adhesion molecule and maps to chromosome 1q22-q23, in the region of the locus for Charcot-Marie-Tooth neuropathy type 1B (CMT1B). We have investigated P0 as a candidate gene in two pedigrees with CMT1B and found point mutations which are completely linked with the disease (Z = 5.5, theta = 0). The mutations, glutamate substitution for lysine 96 or aspartate 90, are located in the extracellular domain, which plays a significant role in myelin membrane adhesion. Individuals with CMT1B are heterozygous for the normal allele and the mutant allele. Our results indicate that P0 is a gene responsible for CMT1B.

Alleles↗
PubMed1993

Dejerine-Sottas syndrome associated with point mutation in the peripheral myelin protein 22 (PMP22) gene.

Dejerine-Sottas syndrome is a hypertrophic, demyelinating neuropathy which appears to demonstrate autosomal recessive inheritance in most pedigrees. Clinical symptoms are similar but more severe than Charcot-Marie-Tooth disease type 1 (CMT1), of which the major subtype, CMT1A, results either from duplication of a 1.5-megabase DNA region in chromosome 17p11.2-p12 containing the myelin gene PMP22, or from PMP22 point mutation. Mutational analysis of the PMP22 coding region in two unrelated Dejerine-Sottas patients identified individual missense point mutations present in the heterozygous state. These findings suggest that Dejerine-Sottas syndrome can result from dominant point mutation alleles of PMP22.

Amino Acid Sequence↗
PubMed1993

Linkage localization of X-linked Charcot-Marie-Tooth disease.

Charcot-Marie-Tooth disease (CMT), also known as hereditary motor and sensory neuropathy, is a heterogeneous group of slowly progressive, degenerative disorders of peripheral nerve. X-linked CMT (CMTX) (McKusick 302800), a subdivision of type I, or demyelinating, CMT is an X-linked dominant condition with variable penetrance. Previous linkage analysis using RFLPs demonstrated linkage to markers on the proximal long and short arms of the X chromosome, with the more likely localization on the proximal long arm of the X chromosome. Available variable simple-sequence repeats (VSSRs) broaden the possibilities for linkage analysis. This paper presents new linkage data and recombination analysis derived from work with four VSSR markers--AR, PGKP1, DXS453, and DXYS1X--in addition to analysis using RFLP markers described elsewhere. These studies localize the CMTX gene to the proximal Xq segment between PGKP1 (Xq11.2-12) and DXS72 (Xq21.1), with a combined maximum multipoint lod score of 15.3 at DXS453 (theta = 0).

Charcot-Marie-Tooth Disease↗
PubMed1992

Analysis of the DNA duplication 17p11.2 in Charcot-Marie-Tooth neuropathy type 1 pedigrees: additional evidence for a third autosomal CMT1 locus.

We have restudied two clinically typical Charcot-Marie-Tooth neuropathy type 1 (CMT1; also known as hereditary motor and sensory neuropathy 1) pedigrees that were previously reported to be unlinked to the regions of proximal chromosome 1q and chromosome 17p by multipoint linkage analyses. In these two pedigrees, there is no evidence for linkage to additional DNA markers that flank and span the CMT1A locus on chromosome 17p11.2, and a duplication associated with CMT1A is not present in these pedigrees. These findings confirm that the CMT1 locus in these two pedigrees does not map to chromosome 17p11.2 or 1q, and provide further evidence for the existence of a third autosomal locus for CMT1.

Charcot-Marie-Tooth Disease↗
PubMed1992

Trisomy 17p associated with Charcot-Marie-Tooth neuropathy type 1A phenotype: evidence for gene dosage as a mechanism in CMT1A.

Charcot-Marie-Tooth neuropathy type 1A (CMT1A) is associated with a DNA duplication on chromosome 17, band p11.2, resulting in partial trisomy for this region in CMT1A patients. The 17p11.2 duplication may lead to the CMT1A phenotype either through disruption of a gene at the duplication breakpoint junction or by trisomic dosage and overexpression of a gene within the duplication. To test the latter model, we evaluated a patient with complete translocation trisomy 17p for signs of CMT1A. In addition to the dysmorphic features seen in trisomy 17p, a neurologic examination and electrophysiologic studies detected a demyelinating neuropathy, compatible with CMT1A. A karyotype on the patient's father found a balanced translocation [t(14;17)] with breakpoints on chromosome 17 in either band p11.1 or proximal p11.2. An analysis of the patient's DNA confirmed trisomy 17p and mapped the translocation breakpoint to a region in 17p11.2, proximal to the duplication breakpoint in CMT1A. Our observations in this patient with trisomy 17p are relevant to an understanding of the genetic mechanism in CMT1A and provide strong evidence that gene dosage through segmental trisomy for 17p11.2 results in the CMT1A phenotype.

Adolescent↗
PubMed1992

Multicolor in situ hybridization and linkage analysis order Charcot-Marie-Tooth type I (CMTIA) gene-region markers.

This study demonstrates a clear and current role for multicolor in situ hybridization in expediting positional cloning studies of unknown disease genes. Nine polymorphic DNA cosmids have been mapped to eight ordered locations spanning the Charcot-Marie-Tooth type 1 (CMT1A) disease gene region in distal band 17p11.2, by multicolor in situ hybridization. When used with linkage analysis, these methods have generated a fine physical map and have firmly assigned the CMT1A gene to distal band 17p11.2. Linkage analysis with four CMT1A pedigrees mapped the CMT1A gene with respect to two flanking markers (8B10-5 cM[LOD 5.2]-CMT1A-3.5 cM[LOD 5.3]-10E4). Additional loci were physically mapped and ordered by in situ hybridization and analysis of phase-known recombinants in CMT1A pedigrees. The order determined by multicolor in situ hybridization was 17cen-LEW301-8B10-5H5/6A9-VAW409- 5G7-6G1-4A11-VAW412-10E4-pter. Two ordered probes, 4A11 and 6G1, reside on the same 440-kb partial SfiI restriction fragment. These data demonstrate the ability of in situ hybridization to resolve loci within 0.5 Mb on early-metaphase chromosomes. Multicolor in situ hybridization also excluded the possibility of pericentric inversions in two unrelated patients with CMT1 and neurofibromatosis type 1. When used with pulsed-field gel electrophoresis, multicolor in situ hybridization can establish physical location, order, and distance in closely spaced chromosome loci.

Charcot-Marie-Tooth Disease↗
PubMed1991

Chromosome 1 Charcot-Marie-Tooth disease (CMT1B) locus in the Fc gamma receptor gene region.

The Charcot-Marie-Tooth disease (hereditary motor and sensory neuropathy) loci have been reported to be on at least three chromosomes: 1 (CMT1B, HMSN1B), 17 (CMT1A), and X (CMTX). In this study multipoint linkage analysis of two Duffy-linked families given a combined LOD score of 8.65 to establish that the Duffy-linked CMT1B gene exists in the 18 centimorgan region between the antithrombin III gene and the Duffy/sodium-potassium ATPase loci. The simultaneous segregation of polymorphisms near the CMT1A locus on chromosome 17 excludes linkage to this chromosome region in both families. Polymorphic sites that flank the CMT1B gene have been subchromosomally localized to the proximal chromosome-1 long arm (1q21.2----1q25) by spot blot analysis of sorted chromosomes, polymorphic deletion analysis, in situ hybridization, and multipoint linkage analysis.

Antigens, Differentiation↗
PubMed1990

Genetic linkage and heterogeneity in type I Charcot-Marie-Tooth disease (hereditary motor and sensory neuropathy type I).

The segregation patterns of DNA markers from the pericentromeric regions of chromosomes 1 and 17 were studied in seven pedigrees segregating an autosomal dominant gene for Charcot-Marie-Tooth neuropathy type I (CMT I; hereditary motor and sensory neuropathy I). A multilocus analysis with four markers (pMCR-3, pMUC10, FY, and pMLAJ1) spanning the pericentromeric region of chromosome 1 excluded the CMT I gene from this region in six pedigrees but gave some evidence for linkage to the region of Duffy in one pedigree. Linkage of the CMT I gene to markers in the pericentromeric region of chromosome 17 (markers pA10-41, pEW301, p3.6, and pTH17.19) was established; however, in these seven pedigrees homogeneity analysis with chromosome 17 markers detected significant genetic heterogeneity. This analysis suggested that three of the seven pedigrees are not linked to this same region. Overall, two of the seven CMT I pedigrees were not linked to markers tested from chromosomes 1 or 17. These results confirm genetic heterogeneity in CMT I and implicate the existence of a third autosomal locus, in addition to a locus on chromosome 17, and a probable locus on chromosome 1. This evidence of etiological heterogeneity, supported by statistical tests, will have to be taken into consideration when fine-structure genetic maps of the regions around CMT I are constructed.

Charcot-Marie-Tooth Disease↗
PubMed1987

Genetic linkage relationships of Charcot-Marie-Tooth disease (HMSN-Ib) to chromosome 1 markers.

Hereditary motor and sensory neuropathy-Ib (HMSN-Ib) is a common autosomal dominant disorder linked to the Duffy blood group locus on human chromosome 1. The gene for antithrombin III (AT3) is also located on the long arm of chromosome 1. Using a DNA restriction fragment length polymorphism for AT3, we have investigated the genetic linkage relationship of all three markers (HMSN-Ib, Duffy, and AT3) in two affected families. Neither HMSN-Ib nor Duffy was tightly linked to AT3. The loci for both HMSN-Ib and Duffy must be close to the centromere on chromosome 1, but precise localization and gene order require study of additional markers and more families.

Adolescent↗
PubMed1985

An intragenic deletion of the factor IX gene in a family with hemophilia B.

A family of seven patients severely afflicted with hemophilia B has been studied for their factor IX genes through the use of factor IX cDNA and genomic DNA probes. The patients had detectable (less than 10% of normal) factor IX antigen in urine and no detectable inhibitors in sera to factor IX protein. Based on the DNA hybridization analysis, these patients showed a partial intragenic deletion in their factor IX gene. The deletion included two exons (exons V and VI) coding for the amino acid sequence from number 85 to 195 of the factor IX protein. The deleted portion of the gene contained the entire factor IX activation peptide. The length of the deletion was estimated to be 10 +/- 0.3 kilobase pairs. This specific gene has been named FIXSeattle. In this family both the deletion and a Taq 1 restriction fragment length polymorphism can be used as a useful marker for accurate detection of female carriers of the deficient factor IX gene.

Chromosome Deletion↗
PubMed1983

Genetic linkage evidence for heterogeneity in Charcot-Marie-Tooth neuropathy (HMSN type I).

A genetic linkage study performed on a large family with autosomal dominant Charcot-Marie-Tooth neuropathy (HMSN type I) showed affected family members to have slow motor nerve conduction velocities, hypoactive tendon reflexes, and distal muscle weakness and atrophy. Results excluded close linkage of the neuropathy in this family to the Duffy blood group locus on chromosome 1. Previous studies in other families have shown positive linkage of HMSN type I to the Duffy locus. The present results provide support for the concept of genetic heterogeneity in HMSN type I. Comparison of this new family with the previous families showing linkage to Duffy reveals that the hereditary neuropathy not linked to the Duffy locus may have less severe slowing of motor nerve conduction velocities and less prominent onion bulb change evident on sural nerve biopsy.

Adolescent↗