Predictive value of gain of 3q for cervical dysplasia and potential utility in the clinical management of LSIL

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Background: Physicians need better tools for determining whether an LSIL will progress to HSIL or regress. Research demonstrates that the chromosome 3q26 region is found to be amplified in patients with cervical cancer and that the frequency of this 3q gain increases with dysplasia severity. The objective of this study was to demonstrate that 3q can be used as a risk stratification tool to identify patients likely to regress/progress. Methods: Slide-based, archival thin-layer specimens and longitudinal follow-up data for 52 patients (47 usable cases) originally diagnosed as LSIL were obtained from independent cytopathology laboratories. Slides were destained, then hybridized with a single-copy probe for the chromosome 3q26 region and a probe for the centromeric alpha-repeat sequence of chromosome 7, using standard FISH methods. Results: Of the 47 cases analyzed, 30 showed a negative FISH test result for a sensitivity of 92% (95% CI of 64, 100), specificity of 85% (95% CI of 69, 95) and a negative predictive value of 97% (95% CI of 83, 100). In a subset of cases a biopsy was obtained. Of the 32 cases with tissue diagnosis, 11 women had progressed to CIN2+, of which 10 were FISH positive; and 18 of 21 women with tissue diagnosis of ≤CIN1 were FISH negative, for a sensitivity of 91% (95% CI of 59, 100), specificity of 86% (95% CI of 64, 97) and a negative predictive value of 95% (95% CI of 74, 100). If the analysis is confined to the 36 cases for which follow-up of at least 12 months after the index LSIL was available, 26 showed a negative FISH test result for a sensitivity of 100% (95% CI of 48, 100), specificity of 84% (95% CI of 66, 95) and a negative predictive value of 100% (95% CI of 87, 100). Of the 22 cases with tissue diagnosis, 4 women had progressed to CIN2+, all FISH positive; and 16 of 18 women with ≤CIN1 were FISH negative, for a sensitivity of 100% (95% CI of 40, 100), specificity of 89% (95% CI of 65, 99) and a negative predictive value of 100% (95% CI of 79, 100). Conclusions: Analysis of 47 specimens demonstrated the ability of 3q gain to predict disease progression/regression in cytology samples. 3q gain can serve as a risk stratification tool for LSIL cases.

[Table: see text]

Enhanced intracellular availability and survival of hammerhead ribozymes increases target ablation in a cellular model of osteogenesis imperfecta

Antisense hammerhead ribozymes have the capability to cleave complementary RNA in a sequence-dependent manner. In osteogenesis imperfecta, a genetic disorder of connective tissue, mutant collagen type I has been shown to participate in but not sustain formation of the triple helix. Selective ablation of mutant collagen gene transcript could potentially remove the mutant gene product and reverse the dominant-negative effect exerted by the abnormal protein. In earlier studies we showed that the hammerhead ribozyme Col1A1Rz547 selectively cleaved a mutant Col1A1 gene transcript in a murine calvarial osteoblast cell line. In order to test the possible therapeutic efficacy of this approach, a dramatic downregulation of the mutant transcript must be achieved, a function directly related to high steady-state level of intracellular ribozyme. We report significantly enhanced expression of Col1A1Rz547 by vaccinia T7 polymerase following infection with an attenuated T7-pol vaccinia virus as shown both by the intracellular level of the ribozyme and the cleavage of the mutant Col1A1 gene transcript. We also describe the engineering of a multimeric ribozyme construct comprising eight subunits, which can self-cleave to monomers. These studies suggest the potential use of multimeric ribozymes expressed by a vaccinia-based system in the therapy of a variety of disorders.

Split hand foot malformation is associated with a reduced level of Dactylin gene expression

Split hand foot malformation (SHFM) is a congenital limb malformation presenting with a median cleft of the hand and/or foot, syndactyly and polydactyly. SHFM is genetically heterogeneous with four loci mapped to date. Murine Dactylaplasia (Dac) is phenotypically similar, and it has been mapped to a syntenic region of 10q24, where SHFM3 has been localized. Structural alterations of the gene-encoding dactylin, a constituent of the ubiquitinization pathway, leading to reduced levels of transcript have been identified in Dac. Here, we report a significant decrease of Dactylin transcript in several individuals affected by SHFM. This observation supports a central role for dactylin in the pathogenesis of SHFM.

Delivery of a hammerhead ribozyme specifically downregulates mutant type I collagen mRNA in a murine model of osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a systemic heritable disorder of connective tissue, caused by a mutation in one of the genes for type I collagen, whose cardinal manifestation is bone fragility. Several studies have identified two molecular mechanisms of collagen type I defects. In chain exclusion, the mutant chain is not incorporated into the collagen triple helix, whereas in chain nonexclusion, it is. The dominant-negative effect of nonexcluded mutations must be taken into account in all strategies aimed at correcting the collagen defects in individuals affected with moderate or several OI. Herein, we describe the application of hammerhead ribozymes to selectively target the mutant minigene transcript expressed in a murine calvarial osteoblast cell line. Active and control inactive ribozymes were tested in vitro on both mutant and normal targets and in the minigene-expressing cell line. Active ribozyme cleaved its target with high efficiency and specificity in both a time-dependent and dose-dependent manner. After delivery of a ribozyme expression construct, intracellular ribozyme was detected, along with a relative reduction in mutant transcript level.

Distal limb malformations: underlying mechanisms and clinical associations

Congenital malformations of the extremities are conspicuous and have been described through the ages. Over the past decade, a wealth of knowledge has been generated regarding the genetic regulation of limb development and the underlying molecular mechanisms. Recent studies have identified several of the signaling molecules, growth factors, and transcriptional regulators involved in the initiation and maintenance of the apical ectodermal ridge (AER) as well as the molecular markers defining the three axes of the developing limb. Studies of abnormal murine phenotypes have uncovered the role played by genes such as p63 and Dactylin in the maintenance of AER activity. These phenotypes resemble human malformations and in this review we describe the underlying mechanisms and clinical associations of split hand/foot malformation and ectrodactyly-ectodermal dysplasia-cleft lip/palate syndrome, which have both been associated with mutations in the p63 gene.

Novel approach to the molecular diagnosis of Marfan syndrome: application to sporadic cases and in prenatal diagnosis

Marfan syndrome is an autosomal dominant disorder affecting the skeletal, ocular, and cardiovascular systems. Defects in the gene that encodes fibrillin-1 (FBN1), the main structural component of the elastin-associated microfibrils, are responsible for the disorder. Molecular diagnosis in families with Marfan syndrome can be undertaken by using intragenic FBN1 gene markers to identify and track the disease allele. However, in sporadic cases, which constitute up to 30% of the total, DNA-based diagnosis cannot be performed using linked markers but rather requires the identification of the specific FBN1 gene mutation. Due to the size and complexity of the FBN1 gene, identification of a causative Marfan syndrome mutation is not a trivial undertaking. Herein, we describe a comprehensive approach to the molecular diagnosis of Marfan syndrome that relies on the direct analysis of the FBN1 gene at the cDNA level and detects both coding sequence mutations and those leading to exon-skipping, which are often missed by analysis at the genomic DNA level. The ability to consistently determine the specific FBN1 gene mutation responsible for a particular case of Marfan syndrome allows both prenatal and pre-implantation diagnosis, even in sporadic instances of the disease.

Acheiropodia is caused by a genomic deletion in C7orf2, the human orthologue of the Lmbr1 gene

Acheiropodia is an autosomal recessive developmental disorder presenting with bilateral congenital amputations of the upper and lower extremities and aplasia of the hands and feet. This severely handicapping condition appears to affect only the extremities, with no other systemic manifestations reported. Recently, a locus for acheiropodia was mapped on chromosome 7q36. Herein we report the narrowing of the critical region for the acheiropodia gene and the subsequent identification of a common mutation in C7orf2-the human orthologue of the mouse Lmbr1 gene-that is responsible for the disease. Analysis of five families with acheiropodia, by means of 15 polymorphic markers, narrowed the critical region to 1.3 cM, on the basis of identity by descent, and to <0.5 Mb, on the basis of physical mapping. Analysis of C7orf2, the human orthologue of the mouse Lmbr1 gene, identified a deletion in all five families, thus identifying a common acheiropodia mutation. The deletion was identified at both the genomic-DNA and mRNA level. It leads to the production of a C7orf2 transcript lacking exon 4 and introduces a premature stop codon downstream of exon 3. Given the nature of the acheiropodia phenotype, it appears likely that the Lmbr1 gene plays an important role in limb development.

Orthopaedic manifestations of Ehlers-Danlos syndrome

Ehlers-Danlos syndrome is the most prevalent heritable disorder of connective tissue. Musculoskeletal problems include joint pain, swelling and instability, and spinal deformity. This study was undertaken to assess functional orthopaedic problems of patients with Ehlers-Danlos syndrome. Sixty patients with genetically verified Ehlers-Danlos syndrome (range, 8-60 years; mean, 34 years) who attended a National Ehlers-Danlos Syndrome Foundation learning conference were evaluated by questionnaire, clinical examination, and when indicated, radiographs. A database of 250 items per patient was constructed and statistically assessed using analysis of variance. Because of rarity of Types VII and VIII, these two patients were dropped from the analysis. Fifty-eight patients had Ehlers-Danlos syndrome Types I, II, III, or IV and form the study cohort. Among these four types, there were no significant differences in history of joint dislocation, swelling, or types of orthopaedic surgical procedures experienced. Thirty patients with Type III Ehlers-Danlos syndrome reported joint pain more frequently than did patients with Types I, II, or IV. Ambulation was impaired significantly in patients with Type III disorder as a whole, as was functional hand strength and upper extremity function. Back or neck pain was a common (67.2%) report among patients with all types of disease but did not correlate with the presence or absence of spinal deformity. Contrary to most previous reports, the patients in this study showed that Type III Ehlers-Danlos syndrome was the most debilitating form with respect to musculoskeletal function.

Localization of an acromesomelic dysplasia on chromosome 9 by homozygosity mapping

The acromesomelic dysplasias (AMDs) are a group of genetic disorders that primarily affect the middle and distal segments of the extremities. A form of AMD is present on the isolated island of St Helena in the South Atlantic, which has a population of approximately 5500 derived from a number of founder individuals. DNA from four affected individuals and 11 first-degree relatives in four related nuclear families segregating an AMD was collected for gene mapping studies. Six consecutive markers on chromosome 9, spanning an approximately 5 cM region, showed identical homozygosity in all affected individuals, thus identifying a region of homozygosity by descent. Multipoint analysis generated a maximum lod score of Z = 2.85. These data localize the gene for this dysplasia to the pericentromeric region of chromosome 9 where the gene for the Maroteaux form of AMD is situated. The identification of the gene responsible for this disorder may shed further light on the complex processes involved in limb morphogenesis.

The genetic basis of aortic disease. Marfan syndrome and beyond

The Marfan syndrome and related disorders are systemic disorders of connective tissue. Proximal aorta is usually dilated. The molecular basis of Marfan syndrome has been elucidated, thus allowing prenatal diagnosis. Life expectancy has markedly improved due to the widespread use of beta-adrenergic receptor inhibitors and improved surgical management of the aortic disease.

A novel human gene encoding an F-box/WD40 containing protein maps in the SHFM3 critical region on 10q24

We report the cloning and characterization of a new human gene, Dactylin, encoding a novel member of the F-box/WD40 protein family. The Dactylin gene comprises nine exons distributed in more than 85 kb of genomic DNA and encoding a protein with four WD40 repeats and an F-box motif. Northern blot analysis demonstrates a single 2.8 kb transcript in brain, kidney, lung and liver. FISH hybridization localized Dactylin to 10q24.3. Using an Msc I SNP identified in the first exon of the gene, we were able to assign Dactylin within the critical region for Split Hand Split Foot malformation (SHFM3) that has been mapped to 10q24. The SHFM3 phenotype includes absence or hypoplasia of the central digital rays, a deep median cleft and syndactyly of the remaining digits. Recent studies have demonstrated the importance of F-box/WD40 proteins in the regulation of developmental processes, by a mechanism of specific ubiquitinization and subsequent proteolysis of target proteins belonging to the Wnt, Hh and NF-kappaB signaling pathways. The chromosomal location of Dactylin and its putative function as an F-box/WD40 repeat protein, likely to be involved in key signaling pathways crucial for normal limb development, make it a promising candidate gene for SHFM3.

Hammerhead ribozymes targeted to the FBN1 mRNA can discriminate a single base mismatch between ribozyme and target

Hammerhead ribozymes are catalytic RNA molecules that can act in trans, with ribozyme and substrate being two different oligoribonucleotides with regions of complementarity. Mutations in the gene for fibrillin-1 (FBN1) cause Marfan syndrome. The majority of mutations are single-base changes, many of which exert their effect via a dominant-negative mechanism. Previously we have shown that an antisense hammerhead ribozyme, targeted to the FBN1 mRNA can reduce deposition of fibrillin to the extracellular matrix of cultured fibroblasts, suggesting it may be possible to utilize ribozymes to down regulate the production of mutant protein and thus restore normal fibrillin function. This might be achieved by the mutation creating a ribozyme cleavage site that is not present in the normal allele, however this is likely to limit the number of mutations that could be targeted. Alternatively, it might be possible to target the mutant allele via the ribozyme binding arms. To determine the potential of ribozymes to preferentially target mutant FBN1 alleles via the latter approach, the effect of mismatches in helix I of a hammerhead ribozyme, on the cleavage of fibrillin (FBN1) mRNA was investigated. A single base mismatch significantly reduced ribozyme cleavage efficiency both in vitro and in vivo. The discrimination between fully-matched and mismatched ribozyme varied with the length of helix I, with the discrimination being more pronounced in ribozymes with a shorter helix. These data suggest that it should be possible to design hammerhead ribozymes that can discriminate between closely related (mutant and normal) target RNAs varying in as little as a single nucleotide, even if the mutation does not create a ribozyme cleavage site.

Ehlers-Danlos syndromes: revised nosology, Villefranche, 1997. Ehlers-Danlos National Foundation (USA) and Ehlers-Danlos Support Group (UK)

Categorization of the Ehlers-Danlos syndromes began in the late 1960s and was formalized in the Berlin nosology. Over time, it became apparent that the diagnostic criteria established and published in 1988 did not discriminate adequately between the different types of Ehlers-Danlos syndromes or between Ehlers-Danlos syndromes and other phenotypically related conditions. In addition, elucidation of the molecular basis of several Ehlers-Danlos syndromes has added a new dimension to the characterization of this group of disorders. We propose a revision of the classification of the Ehlers-Danlos syndromes based primarily on the cause of each type. Major and minor diagnostic criteria have been defined for each type and complemented whenever possible with laboratory findings. This simplified classification will facilitate an accurate diagnosis of the Ehlers-Danlos syndromes and contribute to the delineation of phenotypically related disorders.

Ehlers-Danlos syndromes: revised nosology, Villefranche, 1997. Ehlers-Danlos National Foundation (USA) and Ehlers-Danlos Support Group (UK)

Categorization of the Ehlers-Danlos syndromes began in the late 1960s and was formalized in the Berlin nosology. Over time, it became apparent that the diagnostic criteria established and published in 1988 did not discriminate adequately between the different types of Ehlers-Danlos syndromes or between Ehlers-Danlos syndromes and other phenotypically related conditions. In addition, elucidation of the molecular basis of several Ehlers-Danlos syndromes has added a new dimension to the characterization of this group of disorders. We propose a revision of the classification of the Ehlers-Danlos syndromes based primarily on the cause of each type. Major and minor diagnostic criteria have been defined for each type and complemented whenever possible with laboratory findings. This simplified classification will facilitate an accurate diagnosis of the Ehlers-Danlos syndromes and contribute to the delineation of phenotypically related disorders.

Ehlers-Danlos syndromes: revised nosology, Villefranche, 1997. Ehlers-Danlos National Foundation (USA) and Ehlers-Danlos Support Group (UK)

Categorization of the Ehlers-Danlos syndromes began in the late 1960s and was formalized in the Berlin nosology. Over time, it became apparent that the diagnostic criteria established and published in 1988 did not discriminate adequately between the different types of Ehlers-Danlos syndromes or between Ehlers-Danlos syndromes and other phenotypically related conditions. In addition, elucidation of the molecular basis of several Ehlers-Danlos syndromes has added a new dimension to the characterization of this group of disorders. We propose a revision of the classification of the Ehlers-Danlos syndromes based primarily on the cause of each type. Major and minor diagnostic criteria have been defined for each type and complemented whenever possible with laboratory findings. This simplified classification will facilitate an accurate diagnosis of the Ehlers-Danlos syndromes and contribute to the delineation of phenotypically related disorders.

Grebe syndrome: clinical and radiographic findings in affected individuals and heterozygous carriers

Grebe syndrome is a recessively inherited acromesomelic dysplasia. We studied, clinically and radiographically, 10 affected individuals, originating from Bahia, Brazil. The phenotype is characterized by a normal axial skeleton and severely shortened and deformed limbs, with a proximo-distal gradient of severity. The humeri and femora were relatively normal, the radii/ulnae and tibiae/fibulae were short and deformed, carpal and tarsal bones were fused, and several metacarpal and metatarsal bones were absent. The proximal and middle phalanges of the fingers and toes were invariably absent, while the distal phalanges were present. Postaxial polydactyly was found in several affected individuals. Several joints of the carpus, tarsus, hand, and foot were absent. Heterozygotes presented with a variety of skeletal manifestations including polydactyly, brachydactyly, hallux valgus, and metatarsus adductus. Grebe syndrome is caused by a missense mutation in the gene encoding cartilage-derived morphogenetic protein-1.

Disruption of human limb morphogenesis by a dominant negative mutation in CDMP1

Chondrodysplasia Grebe type (CGT) is an autosomal recessive disorder characterized by severe limb shortening and dysmorphogenesis. We have identified a causative point mutation in the gene encoding the bone morphogenetic protein (BMP)-like molecule, cartilage-derived morphogenetic protein-1 (CDMP-1). The mutation substitutes a tyrosine for the first of seven highly conserved cysteine residues in the mature active domain of the protein. We demonstrate that the mutation results in a protein that is not secreted and is inactive in vitro. It produces a dominant negative effect by preventing the secretion of other, related BMP family members. We present evidence that this may occur through the formation of heterodimers. The mutation and its proposed mechanism of action provide the first human genetic indication that composite expression patterns of different BMPs dictate limb and digit morphogenesis.

Chronic pain is a manifestation of the Ehlers-Danlos syndrome

The Ehlers-Danlos syndrome (EDS) is a group of heritable systemic disorders of connective tissue manifesting joint hypermobility, skin extensibility, and tissue fragility. Although the presence of pain has been documented in the various types of the EDS, its natural history, distribution, and management have not been defined. We conducted a structured interview in 51 individuals affected with different types of EDS. Affected individuals reported chronic pain of early onset involving most frequently the shoulders, hands, and knees. Pain was generally refractory to a variety of pharmacologic and physical interventions. Chronic pain is a common manifestation of EDS.

Delivery of a hammerhead ribozyme specifically down-regulates the production of fibrillin-1 by cultured dermal fibroblasts

The hammerhead ribozyme is a small catalytic RNA molecule. Potential hammerhead ribozymes that possess a catalytic domain and flanking sequence complementary to a target mRNA can cleave in trans at a putative cleavage site within the target molecule. We have investigated the potential of hammerhead ribozymes to down-regulate the product of the fibrillin-1 gene (FBN1). Fibrillin is a 347 kDa glycoprotein that is a major constituent of the elastin-associated microfibrils. Mutations in the FBN1 gene are responsible for Marfan syndrome (MFS), a common systemic disorder of the connective tissue. Many FBN1 mutations responsible for MFS appear to act in a dominant-negative fashion, raising the possibility that reduction of the amount of product from the mutant FBN1 allele might be a valid therapeutic approach for MFS. A trans-acting hammerhead ribozyme (FBN1-RZ1) targeted to the 5' end of the human FBN1 mRNA has been designed and synthesized, and shown to cleave its target efficiently in vitro. FBN1-RZ1 cleavage is magnesium dependent and efficient at both 37 and 50 degrees C. Delivery of the FBN1-RZ1 ribozyme into cultured dermal fibroblasts, by receptor-mediated endocytosis of a ribozyme-transferrin-polylysine complex, specifically reduces both cellular FBN1 mRNA and the deposition of fibrillin in the extracellular matrix. These results suggest that the use of hammerhead ribozymes is a valid approach to the study of fibrillin gene expression and possibly to the development of a therapeutic approach to MFS.

Preimplantation genetic diagnosis in Marfan syndrome

The in vitro fertilization technology coupled with the ability to amplify DNA from a single cell has been used for the preimplantation genetic diagnosis of Marfan syndrome. An intragenic FBN1 gene marker has been used to track the inheritance of this disorder in a family. Marker genotyping was established following two rounds of amplification. Whenever possible, two blastomeres were separately assayed per embryo. The transfer of five embryos resulted in a singleton pregnancy and the birth of a full-term male infant.

Preimplantation genetic testing for Marfan syndrome

Marfan syndrome (MFS) is an autosomal dominant disease that affects the skeletal, ocular and cardiovascular systems. Defects in the gene that codes for fibrillin (FBN-1) are responsible for MFS. Here we report the world's first use of preimplantation genetic testing (PGT) to achieve a clinical pregnancy and live birth of a baby free of a Marfan mutation. One or two blastomeres from each embryo were tested for a CA repeat within the FBN-1 gene. The prospective mother is homozygous for the CA repeat (2/2) and has two normal copies of the FBN-1 gene, while the prospective father is heterozygous for the CA repeat (1/2), and is affected with the Marfan syndrome. In the father's family, allele 2 segregates with the mutated FBN-1 gene. For PGT, any embryo diagnosed as heterozygous for the CA repeat (1/2) would be presumed to have inherited normal FBN-1 genes from the father and the mother and be unaffected. One in-vitro fertilization (IVF) cycle yielded 12 embryos for preimplantation testing; six of the embryos were heterozygous for the CA repeat (1/2) and presumed to be free of the Marfan mutation. Five of the six embryos were subsequently transferred into the uterus. The fetus was tested by chorionic villus sampling and found to be free of the Marfan mutation by the same linkage analysis, had a normal fetal echocardiogram, and was normal at birth.

A split hand-split foot (SHFM3) gene is located at 10q24-->25

The split hand-split foot (SHSF) malformation affects the central rays of the upper and lower limbs. It presents either as an isolated defect or in association with other skeletal or non-skeletal abnormalities. An autosomal SHSF locus (SHFM1) was previously mapped to 7q22.1. We report the mapping of a second autosomal SHSF locus to 10q24-->25. A panel of families was tested with 17 marker loci mapped to the 10q24-->25 region. Maximum lod scores of 3.73, 4.33 and 4.33 at a recombination fraction of zero were obtained for the loci D10S198, PAX2 and D10S1239, respectively. An 19 cM critical region could be defined by haplotype analysis and several genes with a potential role in limb morphogenesis are located in this region. Heterogeneity testing indicates the existence of at least one additional autosomal SHSF locus.

A common FGFR3 gene mutation in hypochondroplasia

Hypochondroplasia is a genetic disorder of disproportionate short stature. Linkage analysis provisionally placed hypochondroplasia in the chromosome 4p 16.3 region, a location to which the FGFR3 gene has been mapped. The genotyping of a three-generation family showed no recombinants between the hypochondroplasia phenotype and three highly polymorphic markers flanking the FGFR3 gene. Mutation analysis was performed by RT-PCR and direct sequencing. Primers covering most of the coding sequence of the FGFR3 gene were used for RT-PCR of FGFR3 mRNA and PCR amplification of genomic DNA. A C-->A transversion was detected in nucleotide 1659 predicting an N540K substitution in exon 11 which encodes part of the TK1 domain. The same mutation was found in an individual suspected to be an achondroplasia/hypochondroplasia compound phenotype and affected individuals from three other unrelated families. A second mutation, a C-->G transversion, also in nucleotide 1659 was detected in all affected individuals of another family. The latter also predicts an N540K substitution. These findings establish that a common mutation in the FGFR3 gene underlies hypochondroplasia.

Family history of severe cardiovascular disease in Marfan syndrome is associated with increased aortic diameter and decreased survival

OBJECTIVES

We attempted to determine whether a family history of severe cardiovascular disease in patients with the Marfan syndrome is associated with increased aortic dilation or decreased survival, or both.

BACKGROUND

The prognostic importance of a family history of severe cardiovascular disease in patients with the Marfan syndrome has been incompletely examined. We hypothesized that such a family history would correlate with increased aortic dilation and would be associated with decreased survival.

METHODS

One hundred eight affected patients and 48 unaffected family members from 33 multigenerational families with the Marfan syndrome underwent echocardiographic measurement of the aortic root, arch and mid-abdominal aorta. Date of birth and age at death ascertained from family pedigrees were used to perform life table analysis and estimate survival.

RESULTS

Aortic root and arch diameters were significantly greater in patients with a family history of severe cardiovascular disease than in patients without such a family history. Of subjects in the highest quartile for aortic size, > 80% had such a family history in contrast to < 10% of those in the lowest quartile (chi-square 57.37, p < 0.00001). Mean age at death and cumulative probability of survival were significantly lower in patients with such a family history.

CONCLUSIONS

Among patients with the Marfan syndrome, aortic dilation is greater and life expectancy shorter in those with a family history of severe cardiovascular manifestations. These data suggest that such a family history is an important risk factor for cardiovascular events in patients with the Marfan syndrome.

Possible genetic heterogeneity in hypochondroplasia

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Molecular cloning of the microfibrillar protein MFAP3 and assignment of the gene to human chromosome 5q32-q33.2

Microfibrils having a diameter of 10-12 nm, found either in association with elastin or independently, are an important component of the extracellular matrix of many tissues, but characterization of these microfibrils is incomplete. To further our understanding of the gene structure of proteins composing the microfibrils and to identify their chromosomal location, we have cloned and characterized another microfibril protein, designated microfibril-associated protein-3 (MFAP3). The human gene encoding MFAP3 has a very simple structure, containing only two translated exons encoding a protein of 362 amino acids. Monospecific antibodies prepared against the recombinantly expressed protein reacted with the microfibrils found in ocular zonules. MFAP3 does not appear to share homology with any other known protein. The gene was found to be located on chromosome 5q32-q33.2, near the locus 5q21-q31 reported for the fibrillin gene, FBN2, which has been linked to congenital contractural arachnodactyly. MFAP3 is a candidate gene for heritable diseases affecting microfibrils.

Life expectancy in the Marfan syndrome

Data reported in 1972 indicated that lifespan in patients with the Marfan syndrome is markedly shortened, and that most deaths are cardiovascular. This study was performed to determine whether survival in the Marfan syndrome has changed since 1972, and to discern whether treatment (medical or surgical) has altered prognosis. Survival curves were generated on 417 patients from 4 referral centers, with a definite diagnosis of the Marfan syndrome. Birth date, age at death, cardiovascular surgery, or treatment with beta blockers, or any combination of these, were included in the analysis. Forty-seven of 417 patients died. Mean age at death (41 +/- 18 years) was significantly increased compared with age in 1972 (32 +/- 16 years, p = 0.0023). Median (50%) cumulative probability of survival in 1993 was 72 years compared with 48 years in 1972. Of 112 surgically treated patients, 10-year probability of survival was 70%. Patients undergoing surgery after 1980 enjoyed significantly increased survival than patients who had undergone operation before 1980 (p = 0.008). In conclusion, life expectancy for patients with the Marfan syndrome has increased > 25% since 1972. Reasons for this dramatic increase may include (1) an overall improvement in population life expectancy, (2) benefits arising from cardiovascular surgery, and (3) greater proportion of milder cases due to increased frequency of diagnosis. Medical therapy (including beta blockers) was also associated with an increase in probable survival.

A common FGFR3 gene mutation is present in achondroplasia but not in hypochondroplasia

Achondroplasia is the most common type of genetic dwarfism. It is characterized by disproportionate short stature and other skeletal anomalies resulting from a defect in the maturation of the chondrocytes in the growth plate of the cartilage. Recent studies mapped the achondroplasia gene on chromosome region 4p16.3 and identified a common mutation in the gene encoding the fibroblast growth factor receptor 3 (FGFR3). In an analysis of 19 achondroplasia families from a variety of ethnic backgrounds we confirmed the presence of the G380R mutation in 21 of 23 achondroplasia chromosomes studied. In contrast, the G380R mutation was not found in any of the 8 hypochondroplasia chromosomes studied. Furthermore, linkage studies in a 3-generation family with hypochondroplasia show discordant segregation with markers in the 4p16.3 region suggesting that at least some cases of hypochondroplasia are caused by mutations in a gene other than FGFR3.

Psychosocial functioning in the Ehlers-Danlos syndrome

Ehlers-Danlos Syndrome (EDS) is a group of related genetic disorders of connective tissue presenting with joint hypermobility, skin extensibility, and tissue fragility. Although the pathophysiology of EDS is increasingly understood, the psychosocial effects of having EDS have not been examined. We psychologically tested and interviewed 41 adults and 7 children with EDS. Anxiety, depression, anger, and interpersonal concerns were significantly elevated, varying from one-quarter to one-third of patients; over 70% had a history of some mental health care use. Psychological difficulties appear to result from chronic pain and disability, ostracism or avoidance of relationships and social activities, sexual difficulties and reproductive concerns, and frustration with the medical system. Specific types of EDS (e.g., EDS Type I) are associated with greater pain and psychological distress. Psychological intervention, prescribed with the recognition that psychiatric features are secondary to EDS, is recommended for some patients.

The gene for achondroplasia maps to the telomeric region of chromosome 4p

Achondroplasia is the most common type of genetic dwarfism. It is characterized by disproportionate short stature and other skeletal anomalies resulting from a defect in the maturation of the chondrocytes in the growth plate of the cartilage. We have now mapped the achondroplasia gene near the telomere of the short arm of chromosome 4 (4p16.3), by family linkage studies using 14 pedigrees. A positive lod score of z = 3.35 with no recombinants was obtained with an intragenic marker for IDUA. This localization will facilitate the positional cloning of the disease gene.

Marfan syndrome: genetic basis and clinical manifestations

Marfan syndrome is a systemic heritable disorder of connective tissue. The manifestations of the disorder are primarily from the musculoskeletal, cardiovascular, and ocular systems. Marfan syndrome is caused by mutations in the fibrillin gene located on chromosome 15.

Prenatal diagnosis and a donor splice site mutation in fibrillin in a family with Marfan syndrome

The Marfan syndrome, an autosomal dominant connective tissue disorder, is manifested by abnormalities in the cardiovascular, skeletal, and ocular systems. Recently, fibrillin, an elastin-associated microfibrillar glycoprotein, has been linked to the Marfan syndrome, and fibrillin mutations in affected individuals have been documented. In this study, genetic linkage analysis with fibrillin specific markers was used to establish the prenatal diagnosis in an 11-wk-gestation fetus in a four-generation Marfan kindred. At birth, skeletal changes suggestive of the Marfan syndrome were observed. Reverse transcription-PCR amplification of the fibrillin gene mRNA detected a deletion of 123 bp in one allele in affected relatives. This deletion corresponds to an exon encoding an epidermal growth factor-like motif. Examination of genomic DNA showed a G-->C transversion at the +1 consensus donor splice site.

Limb-girdle muscular dystrophy is closely linked to the fibrillin locus on chromosome 15

Limb-girdle Muscular Dystrophy (LGMD) is a rare form of muscular dystrophy inherited as an autosomal recessive trait. The LGMD locus was recently mapped to chromosome 15. We tested the hypothesis that fibrillin is a candidate in the etiology of the disorder by genetic linkage analysis. A large Amish kindred segregating the disorder was genotyped for two markers specific for the fibrillin gene on chromosome 15. A total of 105 individuals were genotyped and a maximum LOD score of Z = 9. 135 at theta = 0.04 was obtained. Our results confirmed the mapping of the LGMD on chromosome 15 and excluded fibrillin as a candidate molecule. These data will be useful in the construction of a fine map of the region surrounding the LGMD locus, a prerequisite for the cloning of the LGMD gene.

The CEPH consortium linkage map of human chromosome 15q

The CEPH consortium map of chromosome 15q is presented. The map contains 41 loci defined by genotypes generated from CEPH family DNAs with 45 different probe and restriction enzyme combinations contributed by 10 laboratories. A total of 29 loci have been placed on the map with likelihood support of at least 1000:1. The map extends from 15q13 to 15q25-qter. Multipoint linkage analyses provided estimates that the male, female, and sex-averaged maps extend for 127, 190, and 158 cM, respectively. The largest interval is 21 cM and is between D15S37 and D15S74. The on-average locus spacing is 5.6 cM and the mean genetic distance between the 21 uniquely placed loci is 8 cM.

Genetic linkage of the Marfan syndrome, ectopia lentis, and congenital contractural arachnodactyly to the fibrillin genes on chromosomes 15 and 5. The International Marfan Syndrome Collaborative Study

BACKGROUND

The large glycoprotein fibrillin is a structural component of elastin-containing microfibrils found in many tissues. The Marfan syndrome has been linked to the fibrillin gene on chromosome 15, but congenital contractural arachnodactyly, which shares some of the physical features of the syndrome, has been linked to the fibrillin gene on chromosome 5.

METHODS

Using specific markers for the fibrillin genes, we performed genetic linkage analysis in 28 families with the Marfan syndrome and 8 families with four phenotypically related disorders--congenital contractural arachnodactyly (3 families), ectopia lentis (2), mitral-valve prolapse syndrome (2), and annuloaortic ectasia (1).

RESULTS

Genetic linkage was established between the Marfan syndrome and only the fibrillin gene on chromosome 15, with a maximum lod score of 25.6 (odds for linkage, 10(25.6):1). Ectopia lentis was also linked to the fibrillin gene on chromosome 15, whereas congenital contractural arachnodactyly was linked to the fibrillin gene on chromosome 5. There was no linkage of mitral-valve prolapse to the fibrillin gene on chromosome 5; studies of chromosome 15 were not informative. Annuloaortic ectasia was not linked to either fibrillin gene.

CONCLUSIONS

The Marfan syndrome appears to be caused by mutations in a single fibrillin gene on chromosome 15. Diagnosis of the Marfan syndrome by genetic linkage and analysis is now feasible in many families.

A linkage map of 10 loci flanking the Marfan syndrome locus on 15q: results of an International Consortium study

Members of an International Consortium for Linkage Analysis of the Marfan Syndrome (MFS1) have pooled data for joint analysis in an attempt to determine the precise location of the MFS1 gene and the order of 10 DNA markers on 15q. Five laboratories performed a total of 2111 genotypes in 22 families consisting of 225 affected and 248 normal subjects. For each marker a mean of 98 meioses was informative. D15S48 and D15S1 were identified as the closest linked markers with 99% upper confidence intervals of 12% and 13% respectively. We have used the CRI-MAP program to construct the most likely order as: D15S24-D15S25-D15S1-MFS1-D15S48-D15S49+ ++-(D15S45/S51)-(D15S29/S38). Placement of D15S2 in relation to -D15S1-D15S48- cannot be determined with certainty. The genetic map of these markers extends 53.6 cM in males and 65.0 cM in females with a sex averaged map of 60.7 cM. The sex difference was statistically significant (p = 0.005). Linkage heterogeneity between 22 MFS1 families was documented (p = 0.009) necessitating the exclusion of one family from the analysis. However, comparison of the remaining 21 families for two point and multipoint lod scores showed no evidence for linkage heterogeneity of the MFS1 locus.

Linkage of Marfan syndrome and a phenotypically related disorder to two different fibrillin genes

Marfan syndrome (MFS), one of the most common genetic disorders of connective tissue, is characterized by skeletal, cardiovascular and ocular abnormalities. The incidence of the disease is about 1 in 20,000, with life expectancy severely reduced because of cardiovascular complications. As the underlying defect is unknown, MFS diagnosis is based solely on clinical criteria. Certain phenotypic features of MFS are also shared by other conditions, which may be genetically distinct entities although part of a clinical continuum. Immunohistochemical studies have implicated fibrillin, a major component of elastin-associated microfibrils, in MFS aetiology. Genetic linkage analysis with random probes has independently localized the MFS locus to chromosome 15. Here we report that these two experimental approaches converge with the cloning and mapping of the fibrillin gene to chromosome 15q15-21, and with the establishment of linkage to MFS. We also isolated a second fibrillin gene and mapped it to chromosome 5q23-31. We linked this novel gene to a condition, congenital contractural arachnodactyly, that shares some of the features of MFS. Thus, the cosegregation of two related genes with two related syndromes implies that fibrillin mutations are likely to be responsible for different MFS phenotypes.

Marfan syndrome is closely linked to a marker on chromosome 15q1.5----q2.1

Marfan syndrome is a systemic disorder of the connective tissue inherited as an autosomal dominant trait. The disorder imparts significant morbidity and mortality. The etiology of the disorder remains elusive. A recent study localized the gene for Marfan syndrome on chromosome 15. We present data showing that marker D15S48 is genetically linked to Marfan syndrome. Pairwise linkage analysis gave a maximum lod (logarithm of odds) score of Z = 11.78 at theta = 0.02. Furthermore our data suggest that the Marfan syndrome locus is possibly flanked on either side by D15S48 and D15S49.

Mild spondyloepiphyseal dysplasia (Namaqualand type): genetic linkage to the type II collagen gene COL2A1

Namaqualand spondyloepiphyseal dysplasia (NSED) is a mild autosomal dominant form of spondyloepiphyseal dysplasia in which changes are maximal in the femoral capital epiphyses and the vertebral bodies. The condition is present in a large multigeneration South African family, and it is clinically important by virtue of severe progressive degenerative osteoarthropathy of the hip joint, which frequently necessitates prosthetic joint replacement in adulthood. Linkage studies using molecular markers have shown that the loci for the NSED and type II collagen genes are linked (LOD score 7.98 at a recombination fraction of .00).

Spondyloepiphyseal dysplasia, mild autosomal dominant type is not due to primary defects of type II collagen

A mild autosomal dominant form of spondyloepiphyseal dysplasia (SED) is present in several generations of a South African family of English stock. This phenotype differs from that of any other previously described. Although type II collagen defects have been found in some families with SED congenita, the phenotype in our family showed discordant segregation with COL2A1 gene associated restriction fragment length polymorphisms (RFLPs), the markers for the structural locus of type II collagen. It is evident that the SED group of disorders is heterogeneous.

Spondyloepiphyseal dysplasia congenita: genetic linkage to type II collagen (COL2AI)

Spondyloepiphyseal dysplasia congenita (SEDC) is an autosomal dominantly inherited chondrodysplasia characterized by disproportionate short stature (short trunk), abnormal epiphyses, and flattened vertebral bodies. Manifestations are present at birth. We ascertained a 4-generation family exhibiting the clinical manifestations of the disorder. Previous evidence suggesting defects of type II collagen associated with the SEDC phenotype led us to genotype the family for various COL2A1 gene-associated RFLPs. A total of 17 affected and unaffected members of this family were studied. The family was informative for a recently discovered HinfI RFLP. No recombinants between the marker and the phenotype were found in eight informative meioses. A maximum LOD score of 3.01 was obtained at a recombination fraction of .00. Our results indicate that the SEDC phenotype in this family is caused by mutations in or very close to the COL2A1 locus.

Consistent linkage of dominantly inherited osteogenesis imperfecta to the type I collagen loci: COL1A1 and COL1A2

The segregation of COL1A1 and COL1A2, the two genes which encode the chains of type I collagen, was analyzed in 38 dominant osteogenesis imperfecta (OI) pedigrees by using polymorphic markers within or close to the genes. This was done in order to estimate the consistency of linkage of OI genes to these two loci. None of the 38 pedigrees showed evidence of recombination between the OI gene and both collagen loci, suggesting that the frequency of unlinked loci in the population must be low. From these results, approximate 95% confidence limits for the proportion of families linked to the type I collagen genes can be set between .91 and 1.00. This is high enough to base prenatal diagnosis of dominantly inherited OI on linkage to these genes even in families which are too small for the linkage to be independently confirmed to high levels of significance. When phenotypic features were compared with the concordant collagen locus, all eight pedigrees with Sillence OI type IV segregated with COL1A2. On the other hand, Sillence OI type I segregated with both COL1A1 (17 pedigrees) and COL1A2 (7 pedigrees). The concordant locus was uncertain in the remaining six OI type I pedigrees. Of several other features, the presence or absence of presenile hearing loss was the best predictor of the mutant locus in OI type I families, with 13 of the 17 COL1A1 segregants and none of the 7 COL1A2 segregants showing this feature.

Linkage analysis in Marfan syndrome

We have analysed 40 marker loci on 13 chromosomes for linkage with Marfan syndrome. None of the loci was linked to the Marfan syndrome locus at theta = 0.00. This study provides a basis for an exclusion map and for further collaboration in mapping of the locus.