 |
|
Genotype and Phenotype Analysis of 171 Patients Referred for Molecular Study of the Fibrillin-1 Gene FBN1 Because of Suspected Marfan Syndrome
Bart Loeys, MD;
Lieve Nuytinck, PhD;
Isabelle Delvaux;
Sylvia De Bie, MS;
Anne De Paepe, MD, PhD
Arch Intern Med. 2001;161:2447-2454.
ABSTRACT
| |
Background Marfan syndrome (MFS) is an underrecognized heritable connective tissue
disorder resulting from mutations in the gene for fibrillin-1 (FBN1). Affected patients are at risk for aortic dissection and/or severe
ocular and orthopedic problems. The diagnosis is primarily based on a set
of well-defined clinical criteria (Ghent nosology). The age-related nature
of some clinical manifestations and variable phenotypic expression may hinder
the diagnosis, particularly in children. Molecular analysis may be helpful
to identify at-risk individuals early and start prophylactic medical treatment. FBN1 mutations have also been reported in patients with
Marfan-related conditions, but it is unknown what proportion of all FBN1 mutation carriers they represent.
Methods We reviewed the clinical and molecular data of 171 consecutive patients
referred for FBN1 analysis because either MFS was
diagnosed or they had signs suggestive of MFS. We compared the incidence of
mutations in patients who fulfilled the clinical diagnostic criteria for MFS
with those who did not.
Results Diagnostic criteria for MFS were fulfilled in 94 patients, 62 (66%)
of whom had an FBN1 mutation. A significantly higher
incidence of ectopia lentis was found in the patients with MFS with an FBN1 mutation vs those without (P=.04).
Among the 77 patients who did not meet the criteria, an FBN1 mutation was found in 9 patients (12%). No correlation was found
between the severity of the phenotype and the position and nature of the FBN1 mutation.
Conclusions This study showed a significant difference in the number of FBN1 mutations between patients fulfilling and those not fulfilling
the diagnostic criteria for MFS, which seems to be a good predictor of the
presence of an FBN1 mutation. A comprehensive clinical
evaluation is mandatory before establishing a definitive diagnosis. An FBN1 mutation analysis is helpful to identify individuals
at high risk for MFS who need careful follow-up, particularly in families
displaying phenotypic variability and in children.
INTRODUCTION
MARFAN SYNDROME (MFS) (Mendelian Inheritance in Man [MIM] 154700) is
a connective tissue disorder with autosomal dominant inheritance and a prevalence
of 2 to 3 per 10 000 individuals.1 Mutations
in the fibrillin-1 gene (FBN1) (MIM 134797) on chromosome
15q21.1 cause MFS.2 The cardinal features involve
the ocular, skeletal, and cardiovascular systems. The syndrome shows complete
penetrance but has a wide interfamilial and intrafamilial variability in phenotypic
expression.3 The most important complication
is a progressive dilatation of the aortic root and ascending aorta, leading
to aortic valve incompetence and aortic dissection. Early recognition of at-risk
individuals, either by clinical or molecular investigations, is important
in view of the available medical and surgical treatments that can significantly
improve life expectancy.4-5
Mutation analysis of the FBN1 gene can detect
at-risk individuals at an early stage and offers the possibility for prenatal
diagnosis. In fact, we are increasingly confronted with requests for FBN1 screening to confirm a presumed diagnosis of MFS.
However, despite advances in the molecular understanding of the disease, the
diagnosis of MFS is still primarily clinical, which relies on the recognition
of a number of clinical manifestations in different body systems. In 1986,
the Berlin nosology outlined a set of diagnostic criteria,6
which, after the introduction of mutation analysis of the FBN1 gene, were shown to be prone to cause an overdiagnosis of MFS.7 The Berlin nosology was therefore revised into a set
of more stringent criteria in the Ghent nosology (Table 1).8
|
|
|
|
Table 1. Diagnostic Criteria According to the Ghent Nosology8*
|
|
|
Interpretation of the diagnostic criteria is not always straightforward
because of phenotypic variability in MFS, incomplete expression in young children,
and clinical overlap with Marfan-related conditions. One concern is that a
too strict interpretation of the Ghent nosology can cause an underdiagnosis
of MFS.
FBN1 mutations have occasionally been reported
in Marfan-related conditions such as familial ectopia lentis,9-11
Marfan-like habitus,11-12 or aortic
dissection.13-14 This led to the
conclusion that FBN1 mutations may underlie a range
of "fibrillinopathies" including severe as well as mild conditions, all of
which share to some extent clinical manifestations of MFS. What proportion
of FBN1 mutation carriers they represent is not known.
We have reviewed the clinical and molecular data obtained during the
last 4 years in 171 consecutive patients referred for FBN1 analysis with a clinical diagnosis or signs suggestive of MFS. Our
purpose was to assess the incidence of FBN1 mutations
in the patients fulfilling and not fulfilling the criteria for MFS and to
evaluate the contribution of molecular studies of the FBN1 gene to the diagnosis of MFS. Finally, we looked for correlations
between the clinical phenotype and the nature of the FBN1 mutation.
PATIENTS, MATERIALS, AND METHODS
CLINICAL EVALUATION
This study included 171 consecutive patients in whom FBN1 mutation analysis was performed. All patients were evaluated against
the revised diagnostic criteria for MFS (Ghent nosology), either through personal
examination by one of the investigators (B.L. and A.D.P.) or by another clinical
geneticist familiar with MFS. A detailed clinical checklist was completed
for each patient. The patients included 103 male subjects and 68 female subjects
with a mean age of 23.3 years; 96 patients were adults ( 18 years), and
75 patients were children (<18 years).
We accepted the diagnosis of MFS in an isolated patient if 2 major manifestations
were present and at least 1 other body system was involved (Table 1). Only 50 (all older than 16 years) of the 171 patients
had an evaluation of the lumbar spine by computed tomography or magnetic resonance
imaging. We therefore relied mainly on the involvement of the skeletal, ocular,
and cardiovascular systems to classify them. In familial cases, the diagnosis
of MFS was established if at least 1 major criterion and the involvement of
a second body system were present and 1 other family member fulfilled the
diagnostic criteria independently. The patients who did not fulfill the diagnostic
criteria for MFS were classified in one of the Marfan-related phenotypes.8, 12, 15-17
From each patient we obtained a blood sample, a skin biopsy specimen for fibroblast
culture, or both.
MOLECULAR ANALYSIS OF THE FBN1 GENE
Genomic DNA (gDNA) was extracted from peripheral blood leukocytes by
the QIAamp DNA blood mini kit (Qiagen Inc, Valencia, Calif) or from skin fibroblasts
by the Easy-DNA kit (Invitrogen Corp, Carlsbad, Calif). Total RNA was prepared
from skin fibroblasts with TRIzol Reagent 100 mL (Life Technologies Inc, Rockville,
Md), and first strand complementary DNA (cDNA) was synthesized by Moloney
murine leukemia virus reverse transcriptase (MMLV-RT) (Life Technologies).
Initially, we disposed only of primers for genomic DNA screening, provided
by the international Marfan consortium (coordinated by H. Dietz, MD, PhD,
Baltimore, Md). Mutation screening of the FBN1 genomic
sequences was performed by amplification of 65 fragments, each presenting
1 exon with flanking intron sequences with an average size of 260 base pairs
(bp).
In a later stage of the study, we obtained primer sequences for cDNA
screening from D. Milewicz, MD, and E. Putman, PhD (Houston, Tex). The complete
cDNA analysis comprised amplification of 24 overlapping fragments with an
average size of 450 bp. The FBN1 cDNA reference sequence
with GenBank accession No. NM_000138 was used (National Center for Biotechnical
Information, Bethesda, Md; available at: http://www.ncbi.nlm.nih.gov).
The FBN1 mutation analysis was performed in
113 patients on gDNA only, in 23 on cDNA only, and in 33 on both. In 2 patients
with severe neonatal presentation of MFS, only the middle region of the FBN1 gene (exon 23-32) could be analyzed because no more
DNA was available.
For mutation screening of polymerase chain reaction fragments, 2 different
approaches were used: conformation sensitive gel electrophoresis18-19
and single-strand conformational polymorphism.20
These techniques have been used successfully by us for collagen mutation screening21 and by others for BRCA122 and TSC223
mutation analysis, for which the mutation detection has been estimated to
be between 60% and 80%.
RESULTS
CLINICAL CLASSIFICATION OF PATIENT GROUPS
Ninety-four patients (56 adults and 38 children) presented with an unequivocal
diagnosis of MFS. Among those, 7 patients had very severe expression of the
syndrome from the neonatal period and were therefore diagnosed as having so-called
neonatal MFS, which is characterized by severe congestive heart failure due
to mitral valve or tricuspid insufficiency, joint contractures, crumpled ears,
and loose skin. The remaining 87 patients all presented with classic MFS according
to the Ghent nosology. In all but 1 (patient 59) the clinical diagnosis could
be made even if the information on the dura was not taken into account. The
distribution of the major manifestations in the 87 patients was as follows:
ectopia lentis in 43 patients (49%), significant aortic dilatation or dissection
in 73 patients (84%), and major skeletal involvement in 47 patients (54%).
Thirty of the 87 patients had a computed tomographic or magnetic resonance
scan of the dura, 18 (60%) of whom had dural ectasia.
Overall, 55 (59%) of the 94 patients had a positive family history,
whereas 39 were sporadic, including the 7 neonates. The remaining 77 patients
(40 adults and 37 children) did not fulfill the diagnostic criteria according
to the Ghent nosology. Among them, 12 children presented a phenotype highly
suggestive of MFS, ie, a characteristic appearance and/or positive family
history. Eight of these patients had 1 major and 1 minor diagnostic criterion
for MFS, 3 had ectopia lentis (among whom 1 also had minor skeletal features),
and 1 had major skeletal involvement and a positive family history. We assumed
that they had not fulfilled the diagnostic criteria because of their young
age and represented cases of "emerging" MFS.
The 25 other children and the 40 adults did not fulfill the diagnostic
criteria because they presented only 1 major criterion or only 1 or more minor
criteria. Even if they develop an additional major criterion in the future
(such as aortic dilatation or dural ectasia), they would still not be diagnosed
as having MFS according to the Ghent nosology. The patients were classified
into 1 of the Marfan-related categories on the basis of their phenotypic characteristics:
- Nineteen patients (16 adults and 3 children) had aortic aneurysm
and/or dissection as the only or predominant feature (MIM 132900). In the
adult group, 11 patients had only aortic disease, 4 had both aortic disease
and minor skeletal involvement, and 1 had cutaneous striae. One child presented
only aortic dilatation, and in the 2 other children, aortic aneurysm was found
together with either aortic valve stenosis or aortic valve insufficiency.
- Six patients (5 adults and 1 child) were diagnosed as having predominant
ectopia lentis (MIM 129600). One adult presented isolated ectopia lentis,
1 had both ectopia lentis and minor skeletal involvement, 1 had mild aortic
dilatation (below 2 SDs), 1 adult only had associated striae, and 1 adult
had striae and minor skeletal involvement. Based on the family history, the
child most likely represented an example of autosomal recessive ectopia lentis
(MIM 225200).
- Seven patients (4 adults and 3 children) had the MASS phenotype
(MIM 157700), defined by the presence of at least 2 of the following symptoms:
myopia, mitral valve prolapse, mild aortic dilatation below 2 SDs, cutaneous
striae, and minor skeletal involvement.
- Eight patients (6 adults and 2 children) presented mitral valve
prolapse syndrome, based on the presence of mitral valve prolapse together
with some skeletal manifestations.
- Twenty-two patients (9 adults and 13 children) presented a Marfan-like
habitus and had a major or minor criterion in the skeletal system. No patient
had major cardiac or ocular involvement, 6 had striae, 2 had mild myopia,
and 1 had pneumothorax.
- Three children presented Shprintzen-Goldberg syndrome (MIM 182212).
Nineteen patients had a computed tomographic or magnetic resonance scan
of the dura, and dural ectasia was absent in all cases.
MOLECULAR DATA
A total of 71 FBN1 mutations were found in
the 171 patients in whom FBN1 mutation analysis was
performed. Four mutations were found in 7 patients with the neonatal Marfan
phenotype, and 58 mutations were identified in the remaining 87 patients with
classic MFS (36 mutations in adults and 22 in children) (Table 2). In the 3 families with MFS in whom no mutation was found,
results of a linkage analysis showed cosegregation of the Marfan phenotype
with the FBN1 gene. However, the size of the families
was too small to obtain a significant log of the odds score.
|
|
|
|
Table 2. List of the 71 FBN1 Mutations With
Clinical and Molecular Data*
|
|
|
In the 77 patients who did not fulfill the MFS criteria, a total of
9 mutations (12%) were identified. Importantly, 6 mutations (patients 1-6)
were found among 12 children with highly suggestive signs of MFS. In addition,
1 mutation was found in a 43-year-old man (patient 65) with severe mitral
valve prolapse, and 2 mutations were detected in patients with predominant
ectopia lentis (patients 66 and 67) (Table
2).
Overall, the detection rate of FBN1 mutations
in the group with MFS was 66% (62 of 94 patients). This percentage might be
higher because 2 patients with neonatal MFS were screened for the middle region
of the gene only. In the group of young children with emerging MFS, the incidence
of mutations was 50% (6 of 12 patients). The incidence of FBN1 mutations in the group with Marfan-related conditions was 5% (3
of 65 patients).
The type of FBN1 mutation identified was heterogeneous
and comprised 42 missense mutations, 9 nonsense mutations, and 20 deletions/insertions
causing in-frame or out-of-frame mutations. Seventy percent (50 of 71 patients)
of the mutations resided within one of the calcium binding epidermal growth
factor–like motifs. Nineteen mutations influenced a crucial cysteine
residue or another highly conserved amino acid involved in calcium binding.
The causal nature of the other missense mutations was assumed on the basis
of the familial segregation of the mutation, its absence in 50 controls, and/or
the occurrence of the same mutation in an unrelated patient with MFS.
GENOTYPE-PHENOTYPE CORRELATION
We could not identify distinguishing features in patients with MFS with
or without an FBN1 mutation except for the presence
of ectopia lentis, which was significantly higher in the mutation group (33
of 58 patients vs 10 of 29;  21 = 4.4, P = .04). No significant difference was observed between both groups
with respect to the familial presentation, the number of affected relatives,24 and the distribution of major manifestations (aortic
dilatation or dissection or major skeletal involvement) (Table 2 and Table 3).
|
|
|
|
Table 3. List of Patients With Classic MFS Without FBN1 Mutations With Clinical and Molecular Data*
|
|
|
Nine of the 71 FBN1 mutations reported here
are recurrent (R545C, C1835Y, IVS 46 + 5G>A, G1013R, R1541X, C781R, R2282W,
I2585T, and R122C), which means that they have either been described by others
previously and/or were found by us in unrelated patients. Overall comparison
of the phenotypic manifestations in patients carrying the same mutation showed
comparable findings.24-30
The atypical joint effusion described in association with the R122C mutation
in one family10 may be coincidental because
it was not found in patients 1 and 11 or other literature reports.29
Three mutations identified in patients with neonatal MFS (patients 69-71)
resided within the middle region of the FBN1 gene
(exons 23-32) and 1 was in exon 4 (patient 68). Mutation A1337P (patient 71)
is the first missense mutation in exon 32 associated with neonatal MFS because
only exon-skipping mutations in this exon have been found in patients with
neonatal MFS.31 The 6 other mutations in the
middle region were found in patients with classic MFS (patients 27-32) and
the mutation in exon 27 was characterized in a patient with mitral valve prolapse
(patient 65).
Variability in phenotypic severity was seen in association with mutations
at the same codon leading to different amino acid substitutions. For example,
the substitution of cysteine 1055 by tryptophan (patient 70) resulted in neonatal
MFS as did the substitution of cysteine 1055 by glycine,32
whereas the substitution of this residu by tyrosine gave rise to classic MFS
(patient 29). On the other hand, extensive phenotypic variability within the
same family was also regularly observed. In contrast to the findings of Collod-Beroud
et al,33 we found that cysteine mutations in
the middle region of the gene (C1055Y and C1339Y) can be associated with ectopia
lentis in classic MFS.
COMMENT
This article presents the results of FBN1 mutation
analysis in a group of 171 patients with a clinical diagnosis or signs suggestive
of MFS. Our data show a significant difference in the number of FBN1 mutations between patients fulfilling and not fulfilling the diagnostic
criteria for MFS (66% vs 12%, respectively) (21
= 53.4, P<.001). All 71 mutations were identified
in patients with neonatal or classic MFS except for 9 patients, among whom
6 children had emerging MFS. This suggests that at least in adults the fulfillment
of the diagnostic criteria according to the Ghent nosology is a good predictor
for the presence of an FBN1 mutation. Moreover, in
most patients with MFS, clinical diagnosis could be established without knowing
the dural involvement.
When comparing the patients with MFS with a mutation with those without,
the incidence of ectopia lentis was the only significantly discriminating
factor, whereas there were no major differences regarding family history or
distribution of other clinical manifestations. Two (patients 66 and 67) of
the 3 patients with a Marfan-related condition in which an FBN1 mutation was found also had ectopia lentis. As such, the presence
of ectopia lentis justifies an FBN1 mutation analysis.
We found a high incidence (6 of 12) of mutations in children with a
phenotype highly suggestive of MFS who were too young to fulfill the diagnostic
criteria. This emphasizes that the expression of MFS in young children may
be incomplete, and a proportion of them represent cases of emerging MFS. It
also illustrates the importance of careful follow-up before establishing or
excluding a diagnosis of MFS.
In our cohort, 3 FBN1 mutations were found
among the 65 patients who did not fulfill the MFS criteria: 2 patients (patients
66 and 67) had predominant ectopia lentis and 1 (patient 65) had mitral valve
prolapse and mild skeletal features. Overall, the current data from the literature,
taken together with the low number of mutations (3 of 65 patients) in this
present study, suggest that the incidence of FBN1
mutations in the Marfan-related phenotypes may be low. In some instances,
these phenotypes represent examples of milder fibrillinopathies. In view of
the marked intrafamilial variability found within families with MFS, the distinction
between MFS and other fibrillinopathies may be arbitrary. Moreover, multiple
clinical evaluations over time may be necessary before classifying a patient
with one of the Marfan-related conditions. For example, Kainulainen et al9 reported 2 patients with so-called predominant ectopia
lentis and mild skeletal features who later developed cardiac manifestations
of MFS.29
A wide range of FBN1 mutations was observed
in this present study. No correlation was found between the severity of the
Marfan phenotype and the position or nature of the FBN1 mutation. Some authors suggested a relationship between the severity
of ocular or cardiac involvement and the presence of either a cysteine substitution34 or an FBN1 mutation in the
middle region of the FBN1 gene,33
but our results do not support these observations. In the absence of any significant
genotype-phenotype correlation, the question remains which factors determine
the severity of the Marfan phenotype in a patient. The present understanding
of the molecular pathogenesis is such that for most mutations (most of which
are missense mutations) a fair amount of the mutant transcript is expressed
and exerts a dominant negative effect over the normal gene product during
the assembly of normal and abnormal fibrillin monomers into microfibrils.35-36 However, severe Marfan phenotypes
were also seen in association with nonsense mutations or with frameshift mutations
that are believed to lead to a nonfunctional FBN1
allele (haploinsufficiency), such as the mutation R1539X (patient 36) and
5898delA (patient 48). In these 2 patients, the level of mutant transcript
measured by us was undetectable. This may reflect the fact that the amount
of mutant transcript measured in fibroblasts is not representative of the
amount of transcript in the target tissues (eg, aorta and zonula ciliaris).
Also, the extensive phenotypic variability seen in some families suggests
that other (epi)genetic or environmental factors may modulate the phenotypic
outcome.
Our overall detection rate for FBN1 mutations
in the group with MFS is about 65%. This still leaves us with a detection
failure rate of 35%. Whether this is due solely to technical reasons or to
the presence of another MFS locus remains an open question. From our limited
linkage data, we have no additional evidence for the latter hypothesis. We
are aware that other methods such as denaturing high-performance liquid chromatography
(DHPLC) and direct sequencing may be more sensitive for mutation screening.
For example, for mutation screening of BRCA1, DHPLC
is superior to single-strand conformational polymorphism.37
For FBN1 mutation screening there is limited experience
with DHPLC, and the current literature data suggest a high sensitivity (76%-100%)26, 38 but with a high rate of false positives
(52%), which induces a higher cost and workload.38
CONCLUSIONS
The diagnosis of MFS in affected adults can usually be made by the established
clinical diagnostic criteria. In affected children, the clinical manifestations
may be incomplete, and in those cases confirmation by molecular diagnosis
can help support the decision making about regular follow-up and preventive
cardiovascular treatment. Moreover, in families showing wide variability in
clinical expression, identification of a disease causing FBN1 mutation may be necessary to confirm or exclude the diagnosis
and identify persons at risk. Despite the fact that the presence of an FBN1 mutation does not predict the severity of the Marfan
phenotype, it offers the possibility for and responds to an increasing demand
for a prenatal or preimplantation genetic diagnosis. The application of more
refined mutation screening techniques will be necessary to resolve the question
about locus heterogeneity in MFS and to address issues about genotype-phenotype
correlation. Follow-up over time will be necessary to determine whether the
presence of an FBN1 mutation influences the clinical
prognosis, particularly in patients who do not meet the clinical diagnostic
criteria for MFS.
AUTHOR INFORMATION
Accepted for publication June 6, 2001.
This work is supported by grant 7.0006.98 from the Fund for Scientific
Research-Flanders, Brussels, Belgium (Dr De Paepe). Dr Loeys is a research
fellow of the Fund for Scientific Research-Flanders.
We gratefully thank H. Dietz, MD, PhD, for giving the manuscript a critical
reading and providing helpful suggestions. We are indebted to Petra Van Acker
for excellent technical assistance and to Sophie Walraedt, MD, for assistance
in collecting data. We also thank the referring physicians who provided clinical
data.
Corresponding author: Anne De Paepe, MD, PhD, Centre for Medical
Genetics, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
(e-mail: anne.depaepe{at}rug.ac.be).
From the Centre for Medical Genetics, Ghent University Hospital, Ghent,
Belgium.
REFERENCES
| |
1. Pyeritz RE. Marfan syndrome and other disorders of fibrillin. In: Rimoin DL, Connor JM, Pyeritz RE, eds. Principles
and Practice of Medical Genetics. 3rd ed. New York, NY: Churchill Livingstone
Inc; 1997:1027-1066.
2. Dietz HC, Cutting GR, Pyeritz RE, et al. Marfan syndrome caused by a recurrent de novo missense mutation in
the fibrillin gene. Nature. 1991;352:337-339.
FULL TEXT
| PUBMED
3. Dietz HC, Pyeritz RE. Mutations in the human gene for fibrillin-1 (FBN1) in the Marfan syndrome and related disorders. Hum Mol Genet. 1995;4:1799-1809.
ABSTRACT
4. Shores J, Berger KR, Murphy EA, Pyeritz RE. Progression of aortic dilatation and the benefit of long-term beta-adrenergic
blockade in Marfan's syndrome. N Engl J Med. 1994;330:1335-1341.
FREE FULL TEXT
5. Gott V, Greene P, Alejo D, et al. Replacement of the aortic root in patients with Marfan's syndrome. N Engl J Med. 1999;340:1307-1313.
FREE FULL TEXT
6. Beighton P, De Paepe A, Danks D, et al. International nosology of heritable disorders of connective tissue
disorders of connective tissue, Berlin. Am J Med Genet. 1988;29:581-594.
FULL TEXT
|
ISI
| PUBMED
7. Pereira L, Levran O, Ramirez F, et al. A molecular approach to the stratification of cardiovascular risk in
families with Marfan's syndrome. N Engl J Med. 1994;331:148-153.
FREE FULL TEXT
8. De Paepe A, Devereux RB, Dietz HC, Hennekam RCM, Pyeritz RE. Revised diagnostic criteria for the Marfan syndrome. Am J Med Genet. 1996;62:417-426.
FULL TEXT
|
ISI
| PUBMED
9. Kainulainen K, Karttunen L, Puhakka L, Sakai L, Peltonen L. Mutations in the fibrillin gene responsible for dominant ectopia lentis
and neonatal Marfan syndrome. Nat Genet. 1994;6:64-69.
FULL TEXT
|
ISI
| PUBMED
10. Stahl-Hallengren C, Ukkonen T, Kainulainen K, et al. An extra cysteine in one of the non-calcium-binding epidermal growth
factor-like motifs of the FBN1 polypeptide is connected
to a novel variant of Marfan syndrome. J Clin Invest. 1994;94:709-713.
11. Hayward C, Brock DJH. Fibrillin-1 mutations in Marfan syndrome and other type-1 fibrillinopathies. Hum Mutat. 1997;10:415-423.
FULL TEXT
|
ISI
| PUBMED
12. Milewicz DM, Grossfield J, Cao SN, Kielty C, Covitz W, Jewett T. A mutation in FBN1 disrupts profibrillin processing
and results in isolated skeletal features of the Marfan syndrome. J Clin Invest. 1995;95:2373-2378.
13. Francke U, Berg MA, Tynan K, et al. A Gly1127Ser mutation in an EGF-like domain of the fibrillin-1 gene
is a risk factor for ascending aortic aneurysm and dissection. Am J Hum Genet. 1995;56:1287-1296.
ISI
| PUBMED
14. Milewicz D, Michael K, Fisher N, Cosinelli J, Markello T, Biddinger A. Fibrillin-1 (FBN1) mutations in patients with
thoracic aortic aneurysms. Circulation. 1996;94:2708-2711.
FREE FULL TEXT
15. Savunen T. Cardiovascular abnormalities in relatives of patients operated on for
annulo-aortic ectasia: a clinical and echocardiographic study on 40 families. Eur J Cardiothorac Surg. 1987;1:3-10.
ABSTRACT
16. Nicod P, Bloor C, Godfrey M, et al. Familial aortic dissecting aneurysms. J Am Coll Cardiol. 1989;13:811-819.
ABSTRACT
17. Tsipouras P, DelMastro R, Sarfarazi M, et al and the International Marfan Collaborative Study. Genetic linkage of the Marfan syndrome, ectopia lentis, and congenital
contractural arachnodactyly to the fibrillin genes on chromosome 15 and 5. N Engl J Med. 1992;326:905-909.
ABSTRACT
18. Ganguly A, Rock MJ, Prockop DJ. Confirmation-sensitive gel electrophoresis for rapid detection of single-base
differences in double-stranded PCR products and DNA fragments: evidence for
solvent-induced bends in DNA heteroduplexes. Proc Natl Acad Sci U S A. 1993;90:10325-10329.
FREE FULL TEXT
19. Korkko J, Annunen S, Pihlajamaa T, Prockop DJ, Ala-Kokko L. Conformation sensitive gel electrophoresis for simple and accurate
detection of mutations: comparison with denaturing gradient gel electrophoresis
and nucleotide sequencing. Proc Natl Acad Sci U S A. 1998;95:1681-1685.
FREE FULL TEXT
20. Orita M, Iwahana H, Kanazawa H, Hayashi K, Sekiya T. Detection of polymorphisms of human DNA by gel electrophoresis as single-strand
conformation polymorphisms. Proc Natl Acad Sci U S A. 1989;86:2766-2770.
FREE FULL TEXT
21. Nuytinck L, Tukel T, Kayserili H, Apak MY, De Paepe A. Glycine to tryptophan substitution in type I collagen in a patient
with OI type III: a unique collagen mutation. J Med Genet. 2000;37:371-375.
FREE FULL TEXT
22. Markoff A, Sormbroen H, Bogdanova N, et al. Comparison of conformation-sensitive gel electrophoresis and single-strand
conformation polymorphism analysis for detection of mutations in the BRCA1
gene using optimized conformation analysis protocols. Eur J Hum Genet. 1998;6:145-150.
FULL TEXT
|
ISI
| PUBMED
23. Choy Y, Dabora S, Hall F, et al. Superiority of denaturing high performance liquid chromatography over
single-stranded conformation and conformation-sensitive gel electrophoresis
for mutation detection in TSC2. Ann Hum Genet. 1999;63:383-391.
FULL TEXT
|
ISI
| PUBMED
24. Hayward C, Porteous ME, Brock DJ. Mutation screening of all 65 exons of the fibrillin-1 gene in 60 patients
with Marfan syndrome: report of 12 novel mutations. Hum Mutat. 1997;10:280-289.
FULL TEXT
|
ISI
| PUBMED
25. Nijbroeck G, Sood S, McIntosh I, et al. Fifteen novel FBN1 mutations causing Marfan
syndrome detected by heteroduplex analysis of genomic amplicons. Am J Hum Genet. 1995;57:8-21.
ISI
| PUBMED
26. Matthews K, Wang M, Corbit CK, Godfrey M. Fibrillin (FBN1) mutations in the "neonatal
region": toward genotype/phenotype correlation in neonatal Marfan syndrome
[abstract No.1966]. Am J Hum Genet. 1995;57(suppl):A339.
27. Liu W, Qian C, Comeau K, Brenn T, Furthmayr H, Francke U. Mutant fibrillin-1 monomers lacking EGF-like domains disrupt microfibril
assembly and cause severe Marfan syndrome. Hum Mol Genet. 1996;5:1581-1587.
FREE FULL TEXT
28. Liu W, Oefner P, Qian C, Odom R, Francke U. Denaturing HPLC-identified novel FBN1 mutations,
polymorphisms, and sequence variants in Marfan syndrome and related connective
tissue disorders. Genet Test. 1997;1:237-242.
PUBMED
29. Black C, Withers AP, Gray JR, Bridges AB, Craig A, Baty DU, Boxer M, et al. Correlation of a recurrent FBN1 mutation (R122C)
with an atypical familial Marfan syndrome phenotype. Hum Mutat. 1998;suppl 1:S198-S200.
30. Halliday D, Hutchinson S, Kettle S, Firth H, Wordsworth P, Handford P. Molecular analysis of eight mutations in FBN1. Hum Genet. 1999;105:587-597.
FULL TEXT
|
ISI
| PUBMED
31. Booms P, Cisler J, Mathews K, et al. Novel exon skipping mutation in the fibrillin-1 gene: two "hot spots"
for the neonatal Marfan syndrome. Clin Genet. 1999;55:110-117.
FULL TEXT
|
ISI
| PUBMED
32. Ades L, Haan E, Colley A, Richards R. Characterisation of four novel fibrillin-1 (FBN1) mutations in Marfan syndrome. J Med Genet. 1996;33:665-671.
ABSTRACT
33. Collod-Beroud G, Lackmy-Port-Lys M, Jondeau G, et al. Demonstration of the recurrence of Marfan-like skeletal and cardiovascular
manifestations due to germline mosaicism for an FBN1
mutation [letter]. Am J Hum Genet. 1999;65:917-921.
FULL TEXT
|
ISI
| PUBMED
34. Schrijver I, Liu W, Brenn T, Furthmayr H, Francke U. Cysteine substitutions in epidermal growth factor-like domains of fibrillin-1:
distinct effects on biochemical and clinical phenotypes. Am J Hum Genet. 1999;65:1007-1020.
FULL TEXT
|
ISI
| PUBMED
35. Dietz HC, McIntosh I, Sakai LY, et al. Four novel FBN1 mutations: significance for
mutant transcript level and EGF-like domain calcium binding in the pathogenesis
of Marfan syndrome. Genomics. 1993;17:468-475.
FULL TEXT
|
ISI
| PUBMED
36. Montgomery RA, Geraghty MT, Bull E, et al. Multiple molecular mechanisms underlying subdiagnostic variants of
Marfan syndrome. Am J Hum Genet. 1998;63:1703-1711.
FULL TEXT
|
ISI
| PUBMED
37. Gross E, Arnold N, Goette J, Schwarz-Boeger U, Kiechle M. A comparison of BRCA1 mutation analysis by direct sequencing, SSCP
and DHPLC. Hum Genet. 1999;105:72-78.
FULL TEXT
|
ISI
| PUBMED
|
