Characterization of fibroblasts with Son of Sevenless-1 mutation.

Although non-syndromic hereditary gingival fibromatosis (HGF) is genetically heterogeneous, etiologic mutations have been identified only in the Son of Sevenless-1 gene (SOS1). To test evidence of increased cell proliferation, we studied histological, morphological, and proliferation characteristics in monolayer and three-dimensional cultures of fibroblasts with the SOS1 g.126,142-126,143insC mutation. Histological assessment of HGF gingiva indicated increased numbers of fibroblasts (30%) and increased collagen (10%). Cell proliferation studies demonstrated increased growth rates and 5-bromo-2-deoxyuridine incorporation for HGF fibroblasts. Flow cytometry showed greater proportions of HGF fibroblasts in the G2/M phase. Attachment of HGF fibroblasts to different extracellular matrix surfaces demonstrated increased formation of protrusions with lamellipodia. HGF fibroblasts in three-dimensional culture showed greater cell proliferation, higher cell density, and alteration of surrounding collagen matrix. These findings revealed that increased fibroblast numbers and collagen matrix changes are associated with mutation of the SOS1 gene in vitro and in vivo.

Evaluation of human leukocyte N-formylpeptide receptor (FPR1) SNPs in aggressive periodontitis patients.

Polymorphonuclear neutrophils (PMNs) are attracted to sites of infection by N-formylpeptide (fMLP) chemoattractants. The high-affinity fMLP receptor (FPR1) of phagocytic cells interacts with bacterial fMLP and mediates chemotaxis, degranulation, and superoxide production. These cellular functions are disrupted in PMN from aggressive periodontitis (AP) patients. Two FPR1 gene single nucleotide polymorphisms (SNPs), c.329T>C and c.378C>G, have been associated with a localized form of AP in African-American patients. To evaluate the generality of these SNPs in AP patients, we sequenced a 363 bp interval of the FPR1 gene in an ethnically diverse group of patients (n=111) and controls (n=115). Neither c.329T>C nor c.378C>G were detected in the 452 alleles sequenced. Six SNPs were identified including two located in the FPR1 second extracellular loop that were significantly associated with the AP phenotype in African-American patients (p.R190W, P=0.0033; and p.N192K, P=0.0018). These two SNPs show three predominant haplotypes, each associated with a different disease risk in African-Americans. These data do not support the hypothesis that the FPR1 SNPs c.329T>C and c.378C>G play an etiologic role in aggressive periodontitis, but do suggest that SNPs in the second extracellular loop may be etiologically important.

Identification of a novel cathepsin C mutation (p.W185X) in a Brazilian kindred with Papillon-Lefèvre syndrome.

Papillon-Lefèvre syndrome (PLS) is an autosomal recessive palmoplantar keratoderma caused by cathepsin C (CTSC) gene mutations. This study reports CTSC mutational and enzyme analyses in a consanguineous Brazilian family with PLS, representing the first enzymatic analysis of a Brazilian kinship with PLS. This family segregates a novel PLS-related mutation, p.W185X, that is associated with a complete loss of enzymatic activity.

Novel COL1A1 mutation (G559C) [correction of G599C] associated with mild osteogenesis imperfecta and dentinogenesis imperfecta.

A genotype-phenotype analysis of a three-generation family segregating for an autosomal-dominant osteogenesis imperfecta (OI) variant is reported here. The family was ascertained through the presentation of a proband concerned about discoloration of her teeth, found to be dentinogenesis imperfecta (DGI). Examination of 36 family members identified 15 individuals with DGI. Linkage studies were performed for genetic markers from candidate intervals known to contain genes responsible for DGI on chromosomes 4q, 7q, and 17q. Conclusive evidence for linkage of DGI was obtained to genetic markers on chromosome 17q21-q22 (DLX-3, Z(max) = 5.34, theta = 0.00). All DGI-affected family members shared a common haplotype, which was not present in individuals without DGI. Haplotype analysis sublocalized the gene to a 5-cM genetic interval that contained the collagen 1 alpha 1 (COL1A1) gene. More than 150 different COL1A1 gene mutations have been associated with various forms of OI, and five of these have been associated with DGI and type IV OI. After excluding these five mutations, mutational analysis was performed on the remaining exons including intron--exon boundaries, which resulted in identification of a Gly559Cys mutation in exon 32, present in all DGI-affected family members. Clinical features segregating with this G559C mutation included hyperextensible joints, joint pain and an increased propensity for bone fractures with moderate trauma. This is the first report of joint pain associated with a COL1A1 mutation and DGI. The mild skeletal features and reduced penetrance of the non-dental findings illustrate the importance of genetic evaluations for families with a history of DGI.

Evidence of genetic heterogeneity for hereditary gingival fibromatosis.

Hereditary Gingival Fibromatosis (HGF) is the most common genetic form of gingival fibromatosis. The condition is most frequently reported to be transmitted as an autosomal-dominant trait, but autosomal-recessive inheritance has also been reported. The clinical presentation of HGF is variable, both in the distribution (number of teeth involved) and in the degree (severity) of expression. It is unknown if the variable clinical expression of HGF in different families is due to variable expression of a common gene mutation, allelic mutations, or non-allelic mutations. The apparently different modes of Mendelian inheritance of HGF suggest genetic heterogeneity. A gene locus for HGF has been localized to a 37-cM genetic interval on chromosome 2p21-p22 (D2S1352, Zmax = 5.10, theta = 0.00) flanked by D2S1788 and D2S441. To evaluate the generality of this linkage, we tested linkage with 9 markers from this candidate region in another large family, segregating for an autosomal-dominant form of generalized HGF, and found no support for linkage with any of these markers. Furthermore, statistical tests of this apparent heterogeneity were highly significant. Analysis of these data provides direct evidence that at least two genetically distinct loci are responsible for autosomal-dominant hereditary gingival fibromatosis.

Evidence of genetic heterogeneity for hereditary gingival fibromatosis / Evidência da heterogenidade genética para fibromatose gengival hereditária

Hereditary gingival fibromatosis (HGF) is the most common genetic form of gingival fibromatosis. The condition is most frequently reported to be transmitted as an autosomal-dominant trait, but autosomal-recessive inheritance has also been report. The clinical presentation of HGF is variable, both in the distribution (number of teeth involved) and in the degree (severity) of expression of HGF in different families is due to variable expression of a common gene mutation, allelic mutations, or non-allelic mutation, allelic mutations. The apparently different modes of Mendelian inheritance of HGF suggest genetic heterogeneity. A gene locus for HGF has been localized to a 37-cM genetic interval on chromosome 2p21-p22 (D2S1352, Zmax=5.10, O = 0.00) flanked by D2S1788 and D2S441. To evaluate the generality of this candidate region in another large family, segregating for an autosomal-dominant form of generalized HGF, and found no support for linkage with any of these markers. Furthermore, statistical tests of this apparent heterogeneity were highly significant. Analysis of these data provides direct evidence that at least two genetically distinct loci are responsible for autosomal-dominant hereditary gingival fibromatosis

Genetic heterogeneity of gingival fibromatosis on chromosome 2p.

Gingival fibromatosis (GF) occurs in several genetic forms as a simple Mendelian trait, in malformation syndromes, and in some chromosomal disorders. Specific genes responsible for GF have not been identified. An autosomal dominant form of hereditary gingival fibromatosis (HGF, MIM 135300) was recently mapped to chromosome 2p21 in a large Brazilian family and there was an earlier report of GF in a boy with a cytogenetic duplication involving 2p13-->p21. We thus hypothesised that a common gene locus may be responsible for GF in both the Brazilian family and the boy with the chromosome 2p duplication. We performed additional genetic linkage studies on the Brazilian family and molecular cytogenetic studies on the patient with the cytogenetic duplication to correlate more precisely the genetic interval of the HGF phenotype with the duplicated 2p interval. Additional linkage analysis of new family members resulted in refinement of the candidate region for HGF to an 8 Mb region. Molecular cytogenetic analysis of the 2p13-->p21 duplication associated with GF showed that the duplicated region was proximal to the candidate interval for HGF. Thus, our results support the presence of two different gene loci on chromosome 2p that are involved in GF.

Genetic linkage of hereditary gingival fibromatosis to chromosome 2p21.

Gingival fibromatosis is characterized by a slowly progressive benign enlargement of the oral gingival tissues. The condition results in the teeth being partially or totally engulfed by keratinized gingiva, causing aesthetic and functional problems. Both genetic and pharmacologically induced forms of gingival fibromatosis are known. The most common genetic form, hereditary gingival fibromatosis (HGF), is usually transmitted as an autosomal dominant trait, although sporadic cases are common and autosomal recessive inheritance has been reported. The genetic basis of gingival fibromatosis is unknown. We identified an extended family (n=32) segregating an autosomal dominant form of isolated gingival fibromatosis. Using a genomewide search strategy, we identified genetic linkage (Zmax=5.05, straight theta=.00) for the HGF phenotype to polymorphic markers in the genetic region of chromosome 2p21 bounded by the loci D2S1788 and D2S441. This is the first report of linkage for isolated HGF, and the findings have implications for identification of the underlying genetic basis of gingival fibromatosis.