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PubMed2005

Cone-rod dystrophy, intrafamilial variability, and incomplete penetrance associated with the R172W mutation in the peripherin/RDS gene.

PURPOSE: To determine the underlying molecular genetic basis of a retinal dystrophy identified in a 5-generation family, and to examine the phenotype and degree of intrafamilial variability. DESIGN: Family genetic study. PARTICIPANTS: Nine affected individuals from a nonconsanguineous British family. METHODS: Ophthalmologic examination, color vision testing, fundus photography, autofluorescence imaging, and electrophysiological assessment were performed. The clinical notes of 2 additional deceased affected family members were also reviewed. Blood samples were taken for DNA extraction, with linkage analysis being performed, and subsequent mutation screening of the peripherin/RDS gene. RESULTS: Linkage analysis established a disease interval on chromosome 6p, which harbored the retinal candidate gene, peripherin/RDS. The 3 coding exons of the peripherin/RDS gene were subsequently screened for mutations in affected and unaffected family members. A nonconservative missense substitution, Arg172Trp (R172W), segregated uniquely in all affected subjects. The majority of subjects carrying the R172W peripherin/RDS mutation complained of reduced central vision starting in the second or third decade, with subsequent gradual deterioration of visual acuity and color vision. Three affected individuals complained of nyctalopia. A range of macular appearances were seen, varying from a typical granular appearance to extensive macular atrophy. Autofluorescence imaging in the majority of individuals identified a highly characteristic speckled macular appearance. All affected subjects had abnormal pattern electroretinograms (ERGs) consistent with macular dysfunction and 4 subjects showed additional full-field ERG abnormalities, providing evidence of generalized retinal dysfunction. There was marked variation in the clinical phenotype in those individuals who carried the R172W peripherin/RDS mutation, ranging from severe cone-rod dystrophy to asymptomatic individuals with normal retinal function. CONCLUSIONS: The Arg172Trp (R172W) peripherin/RDS mutation has been previously reported to cause a fully penetrant progressive macular dystrophy with high intrafamilial and interfamilial consistency of phenotype. This is the first report describing marked intrafamilial variation associated with this mutation, including nonpenetrance. These findings are clinically important in relation to advice on prognosis and accurate genetic counseling.

Adolescent↗
PubMed2004

A clinical and genetic study of 56 Saudi Wilson disease patients: identification of Saudi-specific mutations.

Wilson disease (WD) is a hereditary disorder, with recessive transmission and genetic heterogeneity. Several mutations of ATP7B, the gene underlying WD, were reported in many ethnic groups. In this study, mutation screening in ATP7B of 56 Saudi Arabian WD patients was undertaken. The clinical data of all patients were recorded. The entire ATP7B coding sequence, including intron-exon boundaries were screened for mutation by the polymerase chain reaction (PCR)-based mutation detection technique and DNA sequencing. Thirty-nine patients were symptomatic at presentation and 17 subjects were pre-symptomatic siblings of affected patients. Fourteen patients had neurological, 11 patients had mixed (hepatic and neurological), and 14 patients had hepatic presentations. Family history suggestive of WD was present in 72% of cases and 68% had consanguineous parents. Genetic analysis showed disease-causing mutations in three exons (exons 8, 19 and 21) of the ATP7B gene in 28 patients (50%). Mutations in exons 21 (18 cases) and 19 (one case) were unique for Saudis. This large series of Saudi patients with WD has shown wide variability in the genomic substrate of WD. There is no correlation between genotype and clinical presentation.

Adenosine Triphosphatases↗
PubMed2000

Mutation analysis of the entire PKD1 gene: genetic and diagnostic implications.

Mutation screening of the major autosomal dominant polycystic kidney disease (ADPKD) locus, PKD1, has proved difficult because of the large transcript and complex reiterated gene region. We have developed methods, employing long polymerase chain reaction (PCR) and specific reverse transcription-PCR, to amplify all of the PKD1 coding area. The gene was screened for mutations in 131 unrelated patients with ADPKD, using the protein-truncation test and direct sequencing. Mutations were identified in 57 families, and, including 24 previously characterized changes from this cohort, a detection rate of 52.3% was achieved in 155 families. Mutations were found in all areas of the gene, from exons 1 to 46, with no clear hotspot identified. There was no significant difference in mutation frequency between the single-copy and duplicated areas, but mutations were more than twice as frequent in the 3' half of the gene, compared with the 5' half. The majority of changes were predicted to truncate the protein through nonsense mutations (32%), insertions or deletions (29.6%), or splicing changes (6.2%), although the figures were biased by the methods employed, and, in sequenced areas, approximately 50% of all mutations were missense or in-frame. Studies elsewhere have suggested that gene conversion may be a significant cause of mutation at PKD1, but only 3 of 69 different mutations matched PKD1-like HG sequence. A relatively high rate of new PKD1 mutation was calculated, 1.8x10-5 mutations per generation, consistent with the many different mutations identified (69 in 81 pedigrees) and suggesting significant selection against mutant alleles. The mutation detection rate, in this study, of >50% is comparable to that achieved for other large multiexon genes and shows the feasibility of genetic diagnosis in this disorder.

Alleles↗
PubMed2005

Analysis of mRNA in hemophilia A patients with undetectable mutations reveals normal splicing in the factor VIII gene.

BACKGROUND: haemophilia A (HA) is characterized by partial or total deficiency of factor VIII (FVIII) protein activity. It is caused by a broad spectrum of mutations in the FVIII gene. Despite tremendous improvements in mutation screening methods, in about 2% of HA patients no DNA change could be found, even after sequencing the whole coding part of the FVIII gene including the flanking splice sites, as well as the promotor and the 3' UTR regions. OBJECTIVES, PATIENTS AND METHODS: In the present study we performed a detailed RNA analysis of three groups of patients. The first included control patients with known splicing defects, the second included two patients with already identified nucleotide changes close to splicing sites, that could potentially alter the normal splicing process, and a third group of 11 unrelated patients whose genomic DNA have already been screened for mutations by DHPLC and direct sequencing with no mutation being identified. RESULTS: Both candidate splice site mutations were shown to result in either skipping or alternative splicing of at least one exon, therefore these DNA changes must be considered as causal for the patients' HA phenotype. In contrast, no abnormalities on the RNA level were observed in any of 11 unrelated patients without mutations in the FVIII gene. CONCLUSIONS: These findings exclude mutations that could be located deep in the introns and affecting either normal splicing or lead to mechanisms causing some unknown rearrangements of the FVIII gene. In fact, our results point to the presence of still unknown factor(s) causing HA, which might be either allelic or in the close proximity of the FVIII gene or non-allelic associated with other genetic loci that are involved in the processing of the FVIII protein.

DNA Mutational Analysis↗
PubMed2000

Early detection of lung disease and its association with the nutritional status, genetic background and life events in patients with cystic fibrosis.

Progression of lung disease is the most prominent cause of morbidity and death in patients with cystic fibrosis (CF), but the severity of lung disease and the rate of lung function decline are highly variable. An attempt was made to define accurate estimates of disease progression in these patients early diagnosed and prospectively evaluated until 10 years of age. The primary question to ask was whether functional abnormalities detected already in infancy are associated with functional derangements later on in life, and may be useful as parameters of prognostic value. Early diagnosis of CF can best be achieved by screening of mutation by new techniques (buccal cell brushing) in infants, even when the sweat test or accurate blood sampling is not available. Moreover, in infants lung function can be assessed by infant whole-body plethysmography enabling the study of the interrelationship with delayed weight gain and growth retardation, as well as the associations with the most common disease-causing mutations. Out of a cohort of 80 infants (39 males, 41 females) with CF a follow-up study was started with 50 CF infants diagnosed during infancy (mean age 4.6 +/- 4.0 months; range 0.1-12.7 months) and prospectively evaluated at 6-month intervals during the first 2 years of life. Moreover, in 32 CF children out of this cohort, follow-up was continued until 10 years of age. Differences were encountered with respect to the different events occurring during the first years of life, especially the onset of chronic colonization with Pseudomonas aeruginosa. The association between infant lung function and specific mutations (DeltaF508 homozygotes, frameshift DeltaF508/3905insT compound heterozygotes and nonsense DeltaF508/R553X compound heterozygotes) furthermore revealed that differences in lung function within the genetic groups are mainly related to the degree of pulmonary hyperinflation. Pulmonary hyperinflation was also associated with the degree of impaired nutritional status. An association between impaired gas exchange characteristics at 10 years of age and the degree of pulmonary hyperinflation during infancy finally demonstrates that by early mutation screening, lung function testing and assessment of the nutritional status predictors of disease progression later on in life can be defined. Therefore, preventive therapeutic measures should primarily be based on such prognostic factors.

Age Factors↗
PubMed2005

Early-onset macular degeneration with drusen in a cynomolgus monkey (Macaca fascicularis) pedigree: exclusion of 13 candidate genes and loci.

PURPOSE: To describe hereditary macular degeneration observed in the cynomolgus monkey (Macaca fascicularis), which shares phenotypic features with age-related macular degeneration in humans, and to test the involvement of candidate gene loci by mutation screening and linkage analysis. METHODS: Ophthalmic examinations with fundus photography, fluorescein angiography (FA), indocyanine green angiography (IA), electroretinography (ERG), and histologic studies were performed on both affected and unaffected monkeys in the pedigree. The monkey orthologues of the human ABCA4, VMD2, EFEMP1, TIMP3, and ELOVL4 genes were cloned and screened for mutations by single-strand conformation polymorphism (SSCP) analysis or denaturing high-performance liquid chromatography (DHPLC) and direct sequencing in six affected and five unaffected monkeys from the pedigree and in six unrelated, unaffected monkeys. Subsequently, 13 human macular degeneration loci including these five genes were analyzed to test for linkage with the disease. Nineteen affected and seven unaffected monkeys in the pedigree were analyzed by using human microsatellite markers linked to the 13 loci. RESULTS: Yellowish white spots were observed in the macula and fovea centralis, and in some cases the spots scattered to the peripheral retina along the blood vessels. FA showed hyperfluorescence corresponding to the dots except in the foveola. No anomalies were found by IA and ERG. Histologic studies demonstrated that the spots were drusen. Mutation analysis of the ABCA4, VMD2, EFEMP1, TIMP3, and ELOVL4 genes identified a few sequence variants, but none of them segregated with the disease. Linkage analysis with markers linked to these five genes and an additional eight human macular degeneration loci failed to establish linkage. Haplotype analysis excluded the involvement of the 13 candidate loci for harboring the gene associated with macular degeneration in the monkeys. CONCLUSIONS: Significant homology was identified between monkey and human orthologues of the five macular degeneration genes. Thirteen loci associated with macular degeneration in humans or harboring macular degeneration genes were excluded as causal of early-onset macular degeneration in the monkeys. It is likely that none of these loci, but rather a novel gene, is involved in causing the observed phenotype in this monkey pedigree.

ATP-Binding Cassette Transporters↗
PubMed2000

Investigation of single-strand conformational polymorphism of the TP53 gene in women with a family history of breast cancer.

Breast cancer in families with germ line mutations in the TP53 gene has been described in the medical literature. Mutation screening for susceptibility genes should allow effective prophylactic and preventive measures. Using single-strand conformational polymorphism, we screened for mutations in exons 5, 6, 7 and 8 of gene TP53 in the peripheral blood of 8 young non-affected members (17 to 36 years old) of families with a history of breast cancer. Studies of this type on young patients (mean age, 25 years) are very rare in the literature. The identification of these mutations would contribute to genetic counseling of members of families with predisposition to breast cancer. The results obtained did not show any polymorphism indicating mutation. In our sample, the familial tumorigenesis is probably related to other gene etiologies.

Adolescent↗
PubMed1993

Estimation of the incidence of a rare genetic disease through a two-tier mutation survey.

Recent attempts to detect mutations involving single base changes or small deletions that are specific to genetic diseases provide an opportunity to develop a two-tier mutation-screening program through which incidence of rare genetic disorders and gene carriers may be precisely estimated. A two-tier survey consists of mutation screening in a sample of patients with specific genetic disorders and in a second sample of newborns from the same population in which mutation frequency is evaluated. We provide the statistical basis for evaluating the incidence of affected and gene carriers in such two-tier mutation-screening surveys, from which the precision of the estimates is derived. Sample-size requirements of such two-tier mutation-screening surveys are evaluated. Considering examples of cystic fibrosis (CF) and medium-chain acyl-CoA dehydrogenase deficiency (MCAD), the two most frequent autosomal recessive disease in Caucasian populations and the two most frequent mutations (delta F508 and G985) that occur on these disease allele-bearing chromosomes, we show that, with 50-100 patients and a 20-fold larger sample of newborns screened for these mutations, the incidence of such diseases and their gene carriers in a population may be quite reliably estimated. The theory developed here is also applicable to rare autosomal dominant diseases for which disease-specific mutations are found.

Acyl-CoA Dehydrogenase↗
PubMed2001

Diagnosis of autosomal recessive lamellar ichthyosis with mutations in the TGM1 gene.

BACKGROUND: Autosomal recessive lamellar ichthyosis (ARLI) is a clinically and genetically heterogeneous disorder. In many cases, mutations in the transglutaminase 1 gene (TGM1) have been identified, however, other clinically indistinguishable cases have been linked to chromosomes 2, 3 and 19. Previous studies have failed to establish any correlation between clinical characteristics and genetic mutations. OBJECTIVES: To investigate the molecular basis of ARLI in 10 patients with the typical clinical presentation of the disorder. METHODS: We performed polymerase chain reaction and direct sequencing-based mutation screening in all of these patients, and TGM1 immunofluorescence microscopy and in vitro enzyme activity assays in selected patients. RESULTS: Mutation screening revealed 14 mutations, four of which have been previously described. While immunofluorescence microscopy was negative in patients with non-sense mutations or out-of-frame insertions or deletions, the results were variable in cases with mis-sense mutations and in cases with no mutations in the TGM1 gene. In vitro enzyme activity assays gave results consistent with the mutation data. CONCLUSIONS: Our findings support the importance of mutation screening in the evaluation of ARLI.

Adult↗
PubMed2005

RET mutation status in medullary thyroid cancer(MTC) patients and the significance of genetic screening for mutations in their immediate relatives--a preliminary report.

Multiple Endocrine Neoplasia (MEN) 2A is an inherited disease characterized by the development of medullary thyroid carcinoma (MTC), pheochromocytoma(PHCH) and hyperparathyroidism(HPT). It has recently been shown to be associated with germline mutations in the RET proto-oncogene. Genetic testing for RET mutations will, therefore allow the identification of people with asymptomatic MEN 2 who can be offered prophylactic thyroidectomy and biochemical screening as preventive measures. No genetic study based on RET mutation detection has been available in India so far. The aim of the present study is to detect the proportion of MTC cases having inherited germline or somatic RET mutations and to identify family members at risk for MEN and, thereby the feasibility of screening for MEN. DNA extracted from the peripheral blood and somatic (tumor) tissues were subjected to PCR using primers for exons 10,11 and 16. A few samples were subjected to direct sequencing. Germline mutations were identified in 3 of 4 MEN 2A patients, 18 of 24 sporadic MTC(SMTC), 2 of 4 children of MEN2A and 8 relatives of SMTC. Common mutation was in exon 10 and 11 (c634). It is recommended that RET mutation analysis and counseling of patients and their immediate relatives be introduced on a regular basis to identify gene carriers.

Carcinoma, Medullary↗
PubMed2004

Mutation analysis of the breast cancer gene BRCA1 among breast cancer Jordanian females.

OBJECTIVE: To screen mutations of the tumor suppressor breast cancer susceptibility gene 1 (BRCA1) within 3 exons among Jordanian breast cancer females. METHODS: A total of 135 Jordanian breast cancer females were genetically analyzed by denaturing gradient electrophoresis (DGGE) for mutation detection in 3 BRCA1 exons (2, 11 and 20) between 2000-2002 in Al-Basheer Hospital, Amman, Jordan. RESULTS: Of the studied patients 50 had a family history of breast cancer, 28 had a family history of cancer other than breast cancer, and 57 had no family history of any cancer. Five germline mutations were detected among breast cancer females with a family history of breast cancers (one in exon 2 and 4 mutations in exon 11). Another germline mutation (within exon 11) was detected among breast cancer females with family history of cancer other than breast cancer, and no mutation was detected among breast cancer females with no family history of any cancer or among normal control females. CONCLUSION: Screening mutations within exon 2, exon 11 and exon 20 showed that most screened mutations were within BRCA1 exon 11 among breast cancer Jordanian families with a family history of breast cancer.

Adult↗
PubMed1994

[DNA analysis in classic phenylketonuria--screening for mutations and haplotype analysis in Slovak families].

Authors in this contribution present the results of screening for mutations in PAH gene responsible for classical phenylketonuria (PKU), and that of haplotype analysis, based on DNA analysis in 49 Caucasian families with at least one affected child from Slovak Republic. The clearly predominant PKU mutation in this population was the R408W with proportion of 45.9% among all PKU mutations. In addition four other mutations have been identified: IVS12nt1-10.2%, R158Q-7.1%, R261Q-7.1%, and R252W-2.0%. the overall proportion of identified PKU mutations equals 72.4%. Considering the fact, that these mutations are amenable to rapid and rather simple detection using PCR, the DNA analysis is recommended as a method of direct diagnosis in clinical practice as well as in prevention.

DNA↗
PubMed2005

[Analysis of the pathological features and gene mutations of Chinese patients with Charcot-Marie-Tooth disease].

OBJECTIVE: To analyze the relationship of the pathological features and the gene mutations of Chinese patients with Charcot-Marie-Tooth disease. METHODS: The clinical manifestations and pathological investigations of 26 Chinese patients with Charcot-Marie-Tooth disease, 17 males and 9 females, aged 19.0 (4 - 49), with an average disease course of 0.5 - 30 years, 16 being with CMT1 type and 10 being with CMT2 type. Biopsy of sural nerve was conducted in 26 cases, and gene diagnosis was carried out in 13 cases. RESULTS: Five patients were with peripheral myelin protein-22 (PMP22) duplication, 4 of which showed demyelination, 4 of which showed incrassation of myelin sheath, and two of which showed "onion bulb" change without axonal denaturation. Four cases were with connexin 32 (Cx32) point mutations, 3 of which showed demyelination and one of which showed incrassation of myelin sheath and absence of axonal denaturation. The 2 patients with heat shock protein 22 (Hsp22) and heat shock protein 27 (Hsp27) point mutations both showed axonal atrophy, axonal loss and axonal regeneration. CONCLUSION: The pathological findings of the Chinese CMT patients performed by mutation screening were not completely consistent with the pathological features reported abroad. The results of the mutation screening are consistent with the pathological features; mutation screening has the character of high accuracy, little harm and helps diagnose early, so it is suggested to be performed widely clinically, especially to the patients who has family history or to their lineal relatives.

Adolescent↗
PubMed2007

[Screening for mutations in the hotspot mutation regions of PIK3CA gene in nasopharyngeal carcinoma].

BACKGROUND & OBJECTIVE: Recent studies showed high frequency of phosphatidylinositol 3-kinase catalytic alpha polypeptide (PIK3CA) mutations in various human cancers; notably, these mutations frequently locate in the hotspot mutation regions of PIK3CA exon 9 and exon 20 with functional significance in tumorigenesis, invasion, and anti-apoptosis. This study was to screen for mutations in the hotspot mutation regions of PIK3CA in nasopharyngeal carcinoma (NPC), and explore the correlation of PIK3CA mutations to tumorigenesis of NPC. METHODS: PIK3CA exon 9 and exon 20 in 46 specimens of sporadic primary NPC tissues were screened by polymerase chain reaction (PCR)-clone sequencing; those in 46 samples of matched NPC peripheral blood and 3 NPC cell lines CNE1, CNE2, and SUNE1 were directly sequenced. RESULTS: Among the 46 specimens of NPC, 2 (4.3%) had point mutation in PIK3CA exon 9 [T1563G (521Asn-->Lys) and A1646G (549Asp-->Gly)], 18 had multiple mutations in PIK3CA exon 9 (A1634C-G1658C-del 1659T), which might be the homologous sequence of Cat Eye Syndrome region on 22q11.2; none had mutation in PIK3CA exon 20. Moreover, no mutation was detected in PIK3CA exon 9 and exon 20 in the 46 matched NPC peripheral blood samples and CNE1, CNE2, and SUNE1 cells. CONCLUSIONS: PIK3CA exon 9 and exon 20 rarely mutate in NPC. Clone sequencing is more sensitive than direct sequencing in screening for somatic mutation. A1634C-G1658C-del 1659T mutations in PIK3CA exon 9, detected by clone sequencing, are supposed to be the homologous sequence of Cat Eye Syndrome region on 22q11.2 instead of mutations in PIK3CA.

Base Sequence↗
PubMed1995

Screening for mutations in exon 4 of the LDL receptor gene: identification of a new deletion mutation.

DNA from 14 unrelated New Zealand familial hypercholesterolaemia (FH) heterozygotes, originating from the United Kingdom, was screened for mutations in exon 4 of the low density lipoprotein receptor (LDLR) gene. One patient was heterozygous for mutation D206E, which was initially identified in South Africa. The chromosomal background of this mutant allele was compatible with that described previously in Afrikaner and English patients, suggesting that this mutation originated in the United Kingdom. The 2 bp deletion in codon 206 and mutations D154N and D200G, previously reported in English FH patients, were not detected in this sample. In one of the patients, however, a new deletion of 7 bp was identified after nucleotide 581 (or 582) in exon 4 of the LDLR gene.

Adult↗
PubMed1999

Comparative mutation detection screening of the type VII collagen gene (COL7A1) using the protein truncation test, fluorescent chemical cleavage of mismatch, and conformation sensitive gel electrophoresis.

Mutations in the type VII collagen gene, COL7A1, give rise to the blistering skin disease, dystrophic epidermolysis bullosa. We have developed two new mutation detection strategies for the screening of COL7A1 mutations in patients with dystrophic epidermolysis bullosa and compared them with an established protocol using conformational sensitive gel electrophoresis. The first strategy consisted of an RNA based protein truncation test that amplified the entire coding region in only four overlapping nested reverse transcriptase-polymerase chain reaction assays. These fragments were transcribed and translated in vitro and analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. We have used the protein truncation test procedure to characterize 15 truncating mutations in 13 patients with severe recessive dystrophic epidermolysis bullosa yielding a detection sensitivity of 58%. The second strategy was a DNA-based fluorescent chemical cleavage of mismatch (fl-CCM) procedure that amplified the COL7A1 gene in 21 polymerase chain reaction assays. Mismatches, formed between patient and control DNA, were identified using chemical modification and cleavage of the DNA. We have compared fl-CCM with conformational sensitive gel electrophoresis by screening a total of 50 dominant and recessive dystrophic epidermolysis bullosa patients. The detection sensitivity for fl-CCM was 81% compared with 75% for conformational sensitive gel electrophoresis (p = 0.37 chi2-test). Using a combination of the three techniques we have screened 93 dystrophic epidermolysis bullosa patients yielding an overall sensitivity of 87%, detecting 79 different mutations, 57 of which have not been reported previously. Comparing all three approaches, we believe that no single method is consistently better than the others, but that the fl-CCM procedure is a sensitive, semiautomated, high throughput system that can be recommended for COL7A1 mutation detection.

Collagen↗
PubMed1994

[Screening of newborn infants for cystic fibrosis. A combined analysis of immunoreactive trypsin and delta F508 mutation--a screening without false positive results].

A total of 1081 blood screening cards taken from newborn babies, were anonymously selected for cystic fibrosis (CF) screening by quantitation of immunoreactive trypsin (IRT, Delfia) and by delta F508 mutational analyses using polymerase chain reaction followed by a time resolved fluorescence hybridization assay (Delfia). The IRT values showed a log normal distribution and were significantly higher in girls than boys and in 28 carriers compared with 1052 normals. In 12 newborns, corresponding to 1.02%, an IRT concentration greater than 70 micrograms/l was found. One of these was a delta F508 homozygote with an IRT concentration of 380 micrograms/l. delta F508 mutational analyses showed 1052 normals, 28 heterozygotes, and one homozygote, i.e., a carrier frequency of this mutation for delta F508 of 1:39. In future newborn CF-screening programmes we therefore recommend Delfia IRT followed by Delfia delta F508 analyses for IRT values greater than 70 micrograms/l.

Cystic Fibrosis↗
PubMed2006

Novel mutations of FOXC1 and PITX2 in patients with Axenfeld-Rieger malformations.

PURPOSE: To determine the prevalence of FOXC1 and PITX2 mutations and to assess clinical phenotypes in a cohort of German patients with Axenfeld-Rieger malformations. METHODS: All coding exons of the FOXC1 and PITX2 genes were amplified by PCR from genomic DNA and subjected to direct DNA sequencing. Analysis of mutations in control subjects was performed by restriction fragment length polymorphism (RFLP) analysis. RESULTS: Sequence variants were identified by DNA sequencing in 15 of 19 cases. Mutation screening identified four potentially pathogenic FOXC1 mutations causing amino acid substitutions (P79R, Y115S, G149D, and M161V) that were not present in 100 control subjects. In addition, two different 1-bp deletions causing a frameshift and subsequent premature stop codon were identified in two subjects. One patient harbored a FOXC1 nonsense mutation (S48X). Mutation screening also identified two potentially pathogenic PITX2 mutations (P64L and P64R) in two index patients that were excluded in 100 healthy control subjects. CONCLUSIONS: The findings in the present study clearly demonstrate that FOXC1 and PITX2 mutations are responsible for a significant proportion of Axenfeld-Rieger malformations in Germany.

Amino Acid Sequence↗