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PubMed2000

A double germline mutations in the APC and p53 genes.

Germline mutation in the APC gene is required for the initiation of the development of familial adenomatous polyposis (FAP). According to Fearon and Vogelstein model, further somatic mutations in the K-ras oncogene, DCC gene and p53 tumor suppressor gene are prerequisite for development of colon carcinoma. We have found that the germline mutations in the DNA isolated from lymphocytes of an 18 years old girl with extraordinary expressive phenotype in codons 1060-1061 of the APC gene result in truncation of the APC protein. The mutation in codons 12 and 13 of the K-ras oncogene was not detected, but another germline mutation was found in codon 210 of the p53 gene. Furthermore, no one of these germline mutations was detected in the DNA of peripheral blood lymphocytes of the patient's 21 years old healthy sister. Until now, there has been no evidence about the expressive phenotype due to mutation in codons 1060-1061 of the APC gene; the role of germline missense mutation in codon 210 of the p53 gene in the FAP malignant process remains to be elucidated too. The effect of the combination of germline mutation in two different tumor suppressor genes in the progress of disease is discussed.

Adenomatous Polyposis Coli↗

PubMed2001

Beta-catenin mutations in sporadic fundic gland polyps.

Fundic gland polyp (FGP) is the most common gastric polyp. It occurs sporadically or in association with familial adenomatous polyposis (FAP). FAP patients carry germline mutations of the adenomatous polyposis coli (APC) gene, and previous studies have revealed frequent somatic mutations of the APC gene in FGPs associated with FAP. Although inactivation of the APC gene contributes to histogenesis of FGPs associated with FAP, this rarely happens in sporadic cases. Loss of the APC gene promotes abnormal accumulation of beta-catenin, and mutation of GSK-3 beta phosphorylation sites in the beta-catenin gene can have a similar effect. To elucidate the contribution of beta-catenin gene mutation to the histogenesis of sporadic FGP, we analyzed beta-catenin gene mutation in exon 3 in 45 FGP lesions obtained from 35 patients. Somatic mutations were found in 29 lesions: 28 were missense mutations and one was an in-frame deletion. All of the missense mutations were confined to the former two serine residues of the GSK-3 beta phosphorylation sites and their flanking residues (codons 32, 33, 34, 37). Analysis in cases with multiple FGPs revealed a different mutation in each lesion, indicating their multicentric origin. Therefore, a significant proportion of sporadic FGPs have genetic alterations involving beta-catenin stabilization, as did FAP-associated FGPs.

Adult↗

PubMedDate not supplied

Evidence of multi-step oncogenesis of oral squamous cell carcinoma.

We examined biopsy samples from one oral cancer and three precancerous lesions of the tongue of an 81-year old woman by polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) and sequence analyses using 18 oligonucleotide primer pairs of adenomatous polyposis coli (APC) gene and 5 primers of p53 gene. Normal tongue epithelium adjacent to lesions was used as a control. The four lesions harbored the common mutation of APC gene that was not detected in the control. At codon 1621 in exon 15 of the APC gene there was a C to G substitution resulting in serine (TCA) to stop codon (TGA). No mutation of p53 gene was detected in any samples of the control and three precancerous lesions of the tongue. On the other hand, an A to G substitution at codon 170 in exon 5 of p53 gene resulting in glutamic acid (ACG) to glycine (GCG) was detected in the DNA of her tongue cancer. These results may suggest that the four lesions have the same origin, and that multi-step oncogenesis had occurred, the APC gene alteration being one of the early events in the process of tumorigenesis and p53 gene alteration involved in the late events.

Aged↗

PubMed2001

Familial adenomatous polyposis: more evidence for disease diversity and genetic heterogeneity.

Familial adenomatous polyposis (FAP) is characterised by the presence of profuse colonic carpeting of adenomas throughout the entire colon and rectum. The genetic basis of FAP has been shown to be primarily associated with germline mutations in the APC gene. Notwithstanding, several reports have been published indicating that there is genetic heterogeneity in FAP and that the most likely explanation is the existence of another gene. In this report we further delineate the genotype/phenotype correlation in families that harbour germline mutations in the APC gene and identify some previously unreported changes in the APC gene which predispose to an attenuated disease phenotype. From 53 index patients diagnosed with either FAP or attenuated FAP, 27 harboured changes in the APC gene. The remaining 26 patients were further subgrouped according to their colonic phenotype. There were nine patients with a mixed hyperplastic/adenomatous colonic phenotype and there were 17 patients with an adenomatous colonic phenotype. Evaluation of the disease characteristics of these patients and their families is presented which may aid in the identification of new genes associated with colonic polyposis.

Adenomatous Polyposis Coli↗

PubMed1992

Cell and molecular biology of gastrointestinal tract cancer.

The gene for familial adenomatous polyposis coli (APC or FAP), which has previously been linked to chromosome 5q21 has been identified. The APC gene has been found to be altered by point mutations in the germ line of both adenomatous polyposis coli and Gardner's syndrome patients and somatically in tumors from sporadic colorectal cancer patients. During the hunt for the APC gene, the closely linked MCC (mutated in colorectal cancer) gene was identified and found to be altered somatically in tumors from sporadic cancer patients. These data suggest that more than one gene on chromosome 5q21 may contribute to colorectal carcinogenesis and that mutations at the APC gene can cause both adenomatous polyposis coli and Gardner's syndrome. The identification of these genes should aid in the counseling of patients with genetic predispositions to colorectal cancer. Progress has also been made in identifying specific genetic changes that occur in other gastrointestinal cancers. A mutational "hotspot" in the p53 gene in human hepatocellular carcinomas has been identified that could reflect exposure to a specific carcinogen, one candidate being aflatoxin B1.

Adenomatous Polyposis Coli↗

PubMed2004

Zinc stabilizes adenomatous polyposis coli (APC) protein levels and induces cell cycle arrest in colon cancer cells.

In the present study, we investigated the mechanisms by which zinc causes growth arrest in colon cancer cells. The results suggest that zinc treatment stabilizes the levels of the wild-type adenomatous polyposis coli (APC) protein at the post-translational level since the APC mRNA levels and the promoter activity of the APC gene were decreased in HCT-116 cells (which express the wild-type APC gene) after treatment with ZnCl2. Increased levels of wild-type but not truncated APC proteins were required for the ZnCl2-mediated G2/M phase arrest in different colon cancer cell lines. We further tested whether serum-stimulation, which induces cell cycle arrest in the S phase, can relieve ZnCl2-induced G2/M phase arrest of HCT-116 cells. Results showed that in the HCT-116 cells pretreated with ZnCl2, the serum-stimulation neither changed the distribution of G2/M phase arrested cells nor the increased levels of APC protein. The G2/M phase arrest correlated with retarded growth of HCT-116 cells. To further establish that wild-type APC protein plays a role in ZnCl2-induced G2/M arrest, we treated SW480 colon cancer cells that express truncated APC protein. We found that ZnCl2 treatment did not induce G2/M phase arrest in SW480 cells; however, the cell growth was retarded due to the loss of E-cadherin and alpha-tubulin levels. These results suggest that ZnCl2 inhibits the proliferation of colon cancer cells (which carry the wild-type APC gene) through stabilization of the APC protein and cell cycle arrest in the G2/M phase. On the other hand, ZnCl2 inhibits the proliferation of colon cancer cells (which carry the mutant APC gene) by disrupting cellular attachment and microtubule stability.

Adenomatous Polyposis Coli Protein↗

PubMedDate not supplied

Mutational state of von Hippel-Lindau and adenomatous polyposis coli genes in renal tumors.

Genetic alterations of the von Hippel-Lindau (VHL) tumor suppressor gene and the adenomatous polyposis coli (APC) gene in renal tumors were examined by PCR-SSCP analysis and direct sequencing. Tissues from 58 primary sporadic human renal cell tumors (49 clear-cell carcinomas, 6 non-clear-cell carcinomas and 3 oncocytomas) from Japanese patients were used in this study. Somatic VHL mutations were detected in 26 (53%) of the clear-cell carcinomas, although no mutations in this gene were observed in any non-clear-cell carcinomas or oncocytomas. The frequency of mutations did not correlate with histological grade, clinical stage or any of several other clinical factors examined. No differences in the frequency of VHL mutations or in the exons where mutations occurred within the gene were evident when we compared our results with those reported for American patients. However, frameshifts were more common in our Japanese panel of tumors than in American cases, where single-point mutations appear to be more frequent. No APC gene mutation was detected in any of our samples. These results indicate that VHL gene mutations are related to the carcinogenesis of the clear-cell type of primary renal cell carcinomas, whereas alteration of the APC gene is not involved in the pathogenesis of this cancer.

Adenomatous Polyposis Coli↗

PubMed2001

[Genetic analysis in familial adenomatous polyposis].

BACKGROUND: Familial adenomatous polyposis (FAP) is an autosomal dominantly inherited disorder caused by germline mutations in the APC gene. FAP is characterised by a variable, but normally large number of colorectal adenomas and variations in extracolonic manifestations. These variations are associated with specific mutations of the APC gene. MATERIAL AND METHODS: Representatives from 70 Norwegian families are under molecular investigation. Analyses have so far been concentrated on the part of the APC gene associated with classic FAP. RESULTS: Germline mutations causing FAP have been identified in 36 of the 70 families examined. All mutations identified are confined to the first half of the gene and correlate to classic FAP. INTERPRETATION: Because of the mutation heterogeneity in FAP, the size of the APC gene and variations in phenotype, it is a laborious task to identify the causative mutations. Better approaches to the analysis of the whole APC have now been established and will result in a higher degree of mutation detection independent of phenotype. Family history and phenotype-genotype correlations are still important guidelines for efficient molecular genetic analysis of the APC gene. Genetic surveillance, personal and socio-economic benefits from presymptomatic and predictive testing of members of FAP families are discussed.

Adenomatous Polyposis Coli↗

PubMed1998

The APC variants I1307K and E1317Q are associated with colorectal tumors, but not always with a family history.

Classical familial adenomatous polyposis (FAP) is a high-penetrance autosomal dominant disease that predisposes to hundreds or thousands of colorectal adenomas and carcinoma and that results from truncating mutations in the APC gene. A variant of FAP is attenuated adenomatous polyposis coli, which results from germ-line mutations in the 5' and 3' regions of the APC gene. Attenuated adenomatous polyposis coli patients have "multiple" colorectal adenomas (typically fewer than 100) without the florid phenotype of classical FAP. Another group of patients with multiple adenomas has no mutations in the APC gene, and their phenotype probably results from variation at a locus, or loci, elsewhere in the genome. Recently, however, a missense variant of APC (I1307K) was described that confers an increased risk of colorectal tumors, including multiple adenomas, in Ashkenazim. We have studied a set of 164 patients with multiple colorectal adenomas and/or carcinoma and analyzed codons 1263-1377 (exon 15G) of the APC gene for germ-line variants. Three patients with the I1307K allele were detected, each of Ashkenazi descent. Four patients had a germ-line E1317Q missense variant of APC that was not present in controls; one of these individuals had an unusually large number of metaplastic polyps of the colorectum. There is increasing evidence that there exist germ-line variants of the APC gene that predispose to the development of multiple colorectal adenomas and carcinoma, but without the florid phenotype of classical FAP, and possibly with importance for colorectal cancer risk in the general population.

Adult↗

PubMed2006

Expression of cadherins and catenins correlates with distinct histologic types of ovarian carcinomas.

Alterations in the cadherin-catenin expression and activation of the Wnt signaling have been related to the pathology of ovarian carcinomas. Here, we evaluated the immunoreactivity of cadherins (E-, P-, and N-cadherin and cadherin-11) and catenins (alpha-, beta-, and gamma-catenin and p120) in 86 ovarian tumors. We found significant differences in the expression of all cadherins and catenins among the distinct histologic tumor types. Clear cell tumors were rarely N-cadherin- and P-cadherin-positive and showed reduced membranous expression in all the catenins; Serous carcinomas were frequently N-cadherin- and P-cadherin-positive, mucinous tumors strongly expressed E-cadherin and the catenins in the membrane, and endometrioid tumors characteristically expressed nucleocytoplasmic beta-catenin in most of the cases. We next studied whether allelic losses in the chromosomal regions containing various cadherin genes (16q22) or APC gene (5q21) occurred in ovarian tumors and observed a high frequency of loss of heterozygosity in 16q22 (78%) and 5q21 (33%) regions, but there were no differences among the tumor types analyzed. Finally, we also assessed the molecular alterations responsible for beta-catenin nuclear accumulation in endometrioid tumors by screening for mutations in AXIN1, AXIN2, APC, and KRAS genes. Mutations in KRAS were observed in 2 of 19 tumors, but no mutations were detected in AXIN1, AXIN2, or APC genes. Only beta-catenin gene mutations were associated with nuclear beta-catenin staining in these tumors. In conclusion, different cadherin-catenin expression patterns are associated with distinct histologic types. Oncogenic Wnt signaling plays a role only in endometrioid tumors, where beta-catenin mutations seem to be the main cause of its aberrant expression.

Adenocarcinoma↗

PubMed1998

Infrequent somatic mutation of the adenomatous polyposis coli gene in aberrant crypt foci of human colon tissue.

BACKGROUND: The authors examined somatic mutations of the adenomatous polyposis coli (APC) gene in 84 human aberrant crypt foci (ACF) to determine whether APC gene mutations were involved in the histologic progression of ACF. METHODS: Mutation cluster regions of the APC gene were subjected to polymerase chain reaction single-strand conformation polymorphism analysis and direct sequencing. RESULTS: Four kinds of deletion were detected in the mutation cluster regions of APC gene in five ACF. APC mutation was detected in 1 of 18 ACF with Stage I abnormalities (6%). Four of 10 adenomatous ACF (40%) harbored the mutation. There were no mutations in 56 hyperplastic ACF. CONCLUSIONS: These results suggest that APC mutations may be involved initially in only a limited number of adenomas in ACF.

Adenomatous Polyposis Coli↗

PubMed1999

Notable intrafamilial phenotypic variability in a kindred with familial adenomatous polyposis and an APC mutation in exon 9.

BACKGROUND: The phenotypic spectrum of familial adenomatous polyposis (FAP) varies from the classic appearance of hundreds of adenomatous colonic polyps in the young adult and early onset colorectal cancer, to the occurrence of sparse adenomas in the older adult, "attenuated" FAP, due to mutations at the 5' or 3' ends of the APC gene. AIMS: To investigate marked intrafamilial phenotypic variation occurring in a family with an APC gene mutation in exon 9. PATIENTS: An extended kindred of 22 people of whom 16 had colorectal neoplasia and/or were APC mutation carriers. RESULTS: Phenotypic manifestation varied from classic FAP to a complete lack of clinical or endoscopic, or bioptic disease in five people in three different generations. This occurred in four of them over two generations, in spite of having a confirmed 11 bp insertion causing a frame shift and stop codon (363) in exon 9 of the APC gene. CONCLUSIONS: At present, it is assumed that in this family there is alternative splicing of the APC gene, and/or unidentified modifying genetic factors. The family illustrates the importance of genetic testing in evaluating carrier status and not just clinical examination. This clinical observation also high- lights the dilemma in recognising the possible contribution of low penetrance germline APC mutations to what has been considered "sporadic" colorectal neoplasia.

Adenomatous Polyposis Coli↗

PubMed2001

A de novo deletion of chromosome 5q causing familial adenomatous polyposis, dysmorphic features, and mild mental retardation.

Familial adenomatous polyposis (FAP) is an autosomal dominant disorder that typically presents with colorectal cancer secondary to extensive adenomatous polyps of the colon. The molecular basis and clinical phenotype of FAP are well known. Recurrent episodes of severe abdominal pain and a positive fecal occult blood test in an 18-yr-old boy with mild mental retardation and slight dysmorphic features of the face, head, and skeletal system led to the diagnosis of FAP. The clinical workup revealed the presence of over 100 sessile colonic polyps but no polyp formation in the upper GI tract, no cancer development, nor other FAP-associated lesions. To find out whether there is an association between mental retardation and FAP we performed a chromosome analysis including comparative genomic hybridization and an indirect genotype analysis with polymorphic markers from the APC gene region. Cytogenetic analysis showed an interstitial deletion of chromosomal region 5q that was confined to the region 5q21-q22 by comparative genomic hybridization. The deletion, spanning about 10 centimorgans, encompassed the complete APC gene and can be considered as causative for FAP. Moreover, molecular genetic analysis with polymorphic markers flanking the APC gene demonstrated a de novo deletion on the paternal chromosome. Cytogenetically detectable deletions on chromosome 5 including the APC gene generally lead to an associated gene deletion syndrome. Individuals who present with mild mental retardation and dysmorphic features should therefore be investigated for chromosomal deletions. If the deletion encompasses the APC gene, these patients are at high risk of developing FAP and associated complications.

Abnormalities, Multiple↗

PubMed2004

Genetic changes of the E-cadherin and APC tumour suppressor genes in clear cell renal cell carcinoma.

AIMS: The roles of tumour suppressor genes: adenomatous polyposis coli (APC) and E-cadherin (CDH1) were investigated in clear cell renal cell carcinoma. METHODS: Forty-five human clear cell renal cell carcinomas were tested for APC gene instability by polymerase chain reaction/loss of heterozygosity using the restriction fragment length polymorphism method. E-cadherin gene was analysed by PCR amplification of tetranucleotide marker (D16S752) and the alleles were visualised by PAGE/silver staining. RESULTS: The overall proportion of loss of heterozygosity of the APC gene was 37.5% (9/24). D16S752 marker linked to E-cadherin gene (informativeness 91%) revealed three samples with loss of heterozygosity (7.5%). Interestingly, replication error phenotype was detected in 9.1% of clear cell renal cell carcinoma samples. Multivariate statistical analysis of samples informative for both APC and E-cadherin genes showed that, in this data set, loss of heterozygosity of the APC gene is correlated with advanced age and more severe TNM stages. Genetic changes of the E-cadherin gene, on the other hand, appear to be correlated with younger age groups and less severe TNM stages. CONCLUSIONS: Our results suggest that alterations, both in APC and E-cadherin genes, are involved in the evolution and progression of clear cell renal cell carcinoma. Microsatellite genetic instability of the E-cadherin gene indicates that another cellular mechanism, mismatch repair, may also be targeted in this malignancy.

Adenocarcinoma, Clear Cell↗

PubMed1997

Childhood hepatocellular adenoma in familial adenomatous polyposis: mutations in adenomatous polyposis coli gene and p53.

BACKGROUND & AIMS: Infantile and childhood liver tumors have been found in 0.42% of individuals with a germline mutation in the adenomatous polyposis coli (APC) gene. This study analyzed a hepatocellular adenoma of a 2-year-old child at risk for familial adenomatous polyposis to identify genetic alterations in hepatic tumors initiated by APC germline mutations. METHODS: Mutation screening was performed for the APC gene (protein truncation test and DNA sequence analysis), p53 gene (complementary DNA cloning and sequencing), and members of the Ras gene family (complementary DNA sequence analysis). RESULTS: Both the mother and child had a germinal CGA-->TGA transition at codon 1451 leading to an Arg1451Ter stop mutation in the APC gene. Loss of the wild-type APC allele as a second hit revealed hemizygosity of the inherited mutation in the tumor. Furthermore, a CGC-->CAC transition in the p53 gene of the adenoma resulted in an Arg-->His missense mutation in codon 175. No loss of heterozygosity was detected at the p53 locus. Ras gene mutations were not found. CONCLUSIONS: Biallelic inactivation of APC gene and p53 mutation are early events in hepatocellular tumorigenesis. Additional reports will confirm whether inherited APC gene mutations between codon 1444 and 1578 increase the risk for hepatic tumors.

Adenoma, Liver Cell↗

PubMed2006

Developmental abnormalities in multiple proliferative tissues of Apc(Min/+) mice.

Germ-line mutation of the Apc gene has been linked to familial adenomatous polyposis (FAP) that predisposes to colon cancer. Apc(Min/+) mice, heterozygous for the Apc gene mutation, progressively develop small intestinal tumours in a manner that is analogous to that observed in the colon of patients with FAP (Su et al. 1992; Fodde et al. 1994; Moser et al. 1995). We have studied the effects of Apc gene mutation on murine intestinal and extra-intestinal, proliferatively active tissues. We have contrasted the histology to that of the age- and sex-matched wild-type C57BL/6 mice. Histological assessment of the normal appearing intestinal mucosa demonstrates minimal change in size of crypts. In contrast, villi are longer in the ileum of Apc(Min/+) mice relative to C57BL/6 mice at 12 and 15 weeks of age. Vigorous splenic haematopoiesis in Apc(Min/+) mice was seen at 12 and 15 weeks of age, as reflected by marked splenomegaly, increased splenic haematopoietic cells and megakaryocytes. Peripheral blood counts, however, did not differ between C57BL/6 and Apc(Min/+) mice at 15 weeks of age. Lymphoid depletion in Apc(Min/+) mice was characterized by diminished numbers of splenic lymphoid follicles and small intestinal Peyer's patches. The ovaries of 12- and 15-week-old Apc(Min/+) mice exhibited increased numbers of atretic follicles, and estrous cycling by serial vaginal smears showed tendency of elongation in the mutant mice during these age ranges. The testicles of 10-week-old Apc(Min/+) mice showed increased numbers of underdeveloped seminiferous tubules. Collectively, these data suggest that, in addition to its obvious effects upon intestinal adenoma formation, Apc gene mutation causes impairment of developmental and apparent differentiation blockade in proliferative tissues, including those of the haematopoietic system, lymphoid and reproductive tract.

Adenomatous Polyposis Coli↗

PubMed1996

Loss of the adenomatous polyposis coli gene and human papillomavirus infection in oral carcinogenesis.

Recent evidence suggests that loss of heterozygosity (LOH) of the adenomatous polyposis coli (APC) gene plays a role in colorectal tumorigenesis and other cancers. However, little is known as to whether the APC gene contributes to the pathogenesis of oral squamous cell carcinoma. To assess involvement of both the APC gene and the human papillomavirus (HPV) in the development of oral pre-malignant and malignant lesions, we analysed DNA from 14 paired oral normal and pre-malignant or malignant paraffin-embedded biopsy specimens, and DNA from cultured normal and HPV 16-immortalised oral epithelial cells for the presence of LOH of APC and for HPV infection, using PCR based techniques. LOH of APC occurred in 80% of cases of oral epithelial dysplasia, 67% of carcinoma in situ, 50% of invasive squamous cell carcinoma cases, and in the HPV 16-immortalised oral epithelial cells. HPV was detected in half of the biopsy specimens, with HPV 16 as the dominant type. More than half of the carcinoma cases were found to contain both LOH of APC and HPV infection. These results suggest that LOH of APC is an early event during oral tumorigenesis. Our findings also suggest a strong correlation between HPV infection, particularly HPV 16, and LOH of the APC gene in oral squamous cell carcinomas.

Cell Transformation, Neoplastic↗

PubMed2005

Suggestive linkage of familial primary cutaneous amyloidosis to a locus on chromosome 1q23.

BACKGROUND: There is a high incidence of primary cutaneous amyloidosis (PCA) in South America, South-east Asia and Taiwan. To date, the aetiology of PCA remains unknown, but it is believed to be multifactorial. Although most cases are sporadic, some patients have a family history. Familial aggregation and different susceptibility to PCA among ethnic groups suggest that genetic factors may play an important role in its pathogenesis. However, no genetic loci for familial PCA (FPCA) have been identified so far. OBJECTIVES: In order to identify the susceptibility gene of FPCA, we took a candidate gene approach and performed linkage analysis on chromosome 1q21.3-24.2, including the 1q23.2 region where the gene encoding serum amyloid P component (APCS) is located. PATIENTS AND METHODS: Nine FPCA families including 29 individuals affected with PCA were recruited for this linkage study. Initially, 11 highly polymorphic microsatellite markers spanning the region from 1q21.3 to 1q24.2 were genotyped and revealed a suggestive linkage region. This region was further fine-mapped with seven additional markers. We also re-sequenced the 2.5-kb genomic region of the APCS gene in 29 affected and 42 control individuals. Two-point and multipoint linkage analyses were performed using the LINKAGE program. Nonparametric linkage (NPL) analysis and reconstruction of haplotypes were performed with the GENEHUNTER program. RESULTS: Both two-point and multipoint linkage analysis for all 11 markers generated negative or small positive total lod scores for all nine families. However, when we considered only three families, a maximum two-point total lod score of 2.09 was obtained for the marker D1S2844 at theta = 0.01. A plateau of multipoint total lod score between D1S2768 and D1S2878 with a maximum of 2.48 at the marker D1S2844 was observed. A maximum NPL score of 3.11 (P = 0.008) was also obtained for the marker D1S2878. However, re-sequencing of the APCS gene identified no functional mutation. CONCLUSIONS: Both parametric and nonparametric linkage evidence suggested that a possible susceptibility locus for a subset of FPCA might exist on chromosome 1q23. This is the first report demonstrating suggestive evidence of linkage of FPCA to a locus in this candidate region. No functional sequence variations of the APCS gene were found to be associated with this disease among the study families. Our data imply the existence of at least one additional locus responsible for FPCA in these families, confirming genetic heterogeneity of this skin disorder.

Adolescent↗