Duplication cyst of the antrum: a case report

A four generation family (UoM1) was ascertained with Waardenburg syndrome type 1 (WS1). The proband exhibited both WS1 and septo-optic dysplasia. A G to C transversion was identified in PAX3 exon 7 in four subjects affected with WS1 in this family including the proband. This glutamine to histidine missense mutation at position 391 may also affect splicing. There are over 50 mutations characterised in PAX3 in WS1 patients; however, this is the first example of a WS1 mutation in exon 7 of PAX3.     

Screening of germline mutations in the CDKN2A and CDKN2B genes in Swedish families with hereditary cutaneous melanoma

BACKGROUND: Approximately 10% of human cutaneous melanomas occur in families in which several members are affected. The familial predisposition to this disease is often associated with dysplastic nevus syndrome, a condition in which afflicted family members have multiple dysplastic nevi (atypical moles). The chromosome region 9p21 and markers on chromosomes 1p and 6p have been linked to melanoma susceptibility. The tumor suppressor genes CDKN2A and CDKN2B have been mapped to the 9p21 region, and genetic analyses have revealed the presence of germline CDKN2A alterations in melanoma families. The reported frequencies of such alterations, however, vary among these families. PURPOSE: The present investigation was carried out to determine the frequencies of CDKN2A and CDKN2B germline gene mutations among members in a population-based cohort of Swedish melanoma families (i.e., melanoma kindreds). METHODS: DNA was prepared from blood samples obtained from 181 individuals belonging to 100 melanoma kindreds. The polymerase chain reaction (PCR) technique, followed by single-strand conformation polymorphism (SSCP) and nucleotide sequence analyses, were used to identify the types and frequencies of mutations in exons 1, 1beta, 2, and 3 of the CDKN2A gene and in exons 1 and 2 of the CDKN2B gene. RESULTS: CDKN2A gene aberrations were independently identified by both SSCP and nucleotide-sequence analyses. Nucleotide-sequence analysis identified a single point mutation leading to a substitution of leucine for proline in codon 48 of exon 1 in a family with a history of melanoma and several other cancers. A second abnormality, leading to an insertion of an extra arginine residue at codon number 113 of exon 2, was seen in four separate families. The CDKN2A exon-3 coding region had the wild-type sequence in all samples. No germline mutations were found in the alternative exon 1beta of the CDKN2A gene or in exons 1 and 2 of the CDKN2B gene. CONCLUSIONS: The present investigation demonstrates that CDKN2A germline gene mutations were observed in 7.8% of the 64 Swedish melanoma kindreds that each included at least two first-degree relatives with melanoma and dysplastic nevus syndrome. No CDKN2A exon 1beta or CDKN2B mutations were identified. The critical genes responsible for the inheritance of a susceptibility to develop melanoma among family members in this population have yet to be identified.     

Molecular and cellular basis of radiation fibrosis

From a spina bifida clinic we have identified two patients with a syndrome of myelomeningocele and Waardenburg syndrome type 3 (WS3). The patients each possess a single, de novo, interstitial deletion of chromosome 2 (2q35-36.2), including the PAX3 gene. Deletion of PAX3 was confirmed by fluorescence in situ hybridization (FISH). Analysis with PAX3 and flanking microsatellites shows that the deleted interval of chromosome 2 is of paternal origin and is at least 2 and 6 cM in the two patients. Interstitial deletions in this region result in the Waardenburg syndrome (WS1), but have not been associated with neural tube defects (NTDs). Although other etiologies have not been formally excluded, these patients raise the possibility of a digenic etiology of their NTDs via a genetic interaction of the deleted PAX3 gene with a second unidentified locus.     

Molecular analysis of the PDS gene in Pendred syndrome

Pendred syndrome is an autosomal recessive disorder characterized by the association between sensorineural hearing loss and thyroid swelling or goitre and is likely to be the most common form of syndromic deafness. Within the thyroid gland of affected individuals, iodide is incompletely organified with variable effects upon thyroid hormone biosynthesis, whilst the molecular basis of the hearing loss is unknown. The PDS gene has been identified by positional cloning of chromosome 7q31, within the Pendred syndrome critical linkage interval and encodes for a putative ion transporter called pendrin. We have investigated a cohort of 56 kindreds, all with features suggestive of a diagnosis of Pendred syndrome. Molecular analysis of the PDS gene identified 47 of the 60 (78%) mutant alleles in 31 families (includes three homozygous consanguineous kindreds and one extended family segregating three mutant alleles). Moreover, four recurrent mutations accounted for 35 (74%) of PDS disease chromosomes detected and haplotype analysis would favour common founders rather than mutational hotspots within the PDS gene. Whilst these findings demonstrate molecular heterogeneity for PDS mutations associated with Pendred syndrome, this study would support the use of molecular analysis of the PDS gene in the assessment of families with congenital hearing loss.     

Further delineation of renal-coloboma syndrome in patients with extreme variability of phenotype and identical PAX2 mutations

Renal-coloboma syndrome is a recently described autosomal dominant syndrome of abnormal optic nerve and renal development. Two families have been reported with renal-coloboma syndrome and mutations of the PAX2 gene. The PAX2 gene, which encodes a DNA-binding protein, is expressed in the developing ear, CNS, eye, and urogenital tract. Ocular and/or renal abnormalities have been consistently noted in the five reports of patients with renal-coloboma syndrome, to date, but PAX2 expression patterns suggest that auditory and CNS abnormalities may be additional features of renal-coloboma syndrome. To determine whether additional clinical features are associated with PAX2 mutations, we have used PCR-SSCP to identify PAX2 gene mutations in patients. We report here four patients with mutations in exon 2, one of whom has severe ocular and renal disease, microcephaly, and retardation, and another who has ocular and renal disease with high-frequency hearing loss. Unexpectedly, extreme variability in clinical presentation was observed between a mother, her son, and an unrelated patient, all of whom had the same PAX2 mutation as previously described in two siblings with renal-coloboma syndrome. These results suggest that a sequence of seven Gs in PAX2 exon 2 may be particularly prone to mutation.     

Study on the elimination of Angiostrongylus costaricensis first stage larvae in the experimental infection of Swiss mice

We report six of 16 U.K. melanoma families and two of 17 patients with multiple primary melanomas and a negative family history who have between them four different functionally damaging mutations of the CDKN2A (p16) gene: an Arg 24 Pro substitution in exon 1 in one family, a stop codon at codon 44 of exon 1 in one family, and a Met 53 Ile substitution in exon 2 in four families. One multiple primary melanoma patient also has the Met 53 Ile mutation and a second has a G-T substitution at the IVS2 + 1 splice donor site. Our data together with other recent publications from France and the U.S.A. indicate that screening melanoma kindreds with only two affected family members for CDKN2A mutations is justified.     

Effect of 5-hydroxytryptamine on bioelectric properties of airway epithelial cells in culture

Waardenburg syndrome type 1 is caused by mutations in PAX3. Over 50 human PAX3 mutations that lead to hearing, craniofacial, limb, and pigmentation anomalies have been identified. A PAX3 mutant allele, segregating in a family, can show reduced penetrance and variable expressivity that cannot be explained by the nature of the mutation alone. The Mus musculus Pax3 mutation Spd (Splotch-delayed, Pax3Spd), coisogenic on the C57BL/6J (B6) genetic background, produces in heterozygotes a white belly spot with 100% penetrance and very few other anomalies. By contrast, many Spd/+ BC1 progeny [F1 female Spd/+ (female Spd/+ B6 x male +/+ Mus spretus) x male +/+ B6] exhibit highly variable craniofacial and pigmentary anomalies. Of the BC1 Spd/+ progeny, 23.9% are estimated to be nonviable, and 32.1% are nonpenetrant for the white belly spot. The penetrance and expressivity of the Spd/+ genotype are controlled in part by the genetic background and the sex of the individual. A minimum of two genes interact with Spd to influence the craniofacial features of these mice. One of these genes may be either X-linked or sex-influenced, while the other is autosomal. The A-locus (Agouti) or a gene closely linked to A also plays a role in determining craniofacial features. At least one additional gene, possibly the A-locus or a gene linked to A, interacts with Spd and determines the presence and size of the white belly spot. The viability of BC1 mice is influenced by at least three factors: Spd, A-locus alleles or a gene closely linked to the A-locus, and the sex of the mouse. These BC1 mice provide an opportunity to identify genes that interact with and modify the expression of Pax3 and serve as a model to identify the genes that modify the expression of human PAX3 mutations.     

Novel germline mutations in the APC gene and their phenotypic spectrum in familial adenomatous polyposis kindreds

Among 23 germline mutations identified in the APC screening of 45 familial adenomatous polyposis (FAP) patients, we have found 10 different novel frameshift mutations in 11 apparently unrelated patients. In two cases, an additional missense mutation was detected. One previously described as a causative germline mutation (S2621C), associated with a 1-bp insertion (4684insA) on the opposite allele, did not segregate with the FAP phenotype in the family and was therefore considered as being non-pathogenic. The other (Z1625H) was located 2 codons before a 1-bp deletion (4897delC). Both mutations were transmitted together from an FAP father to his affected son. The FAP phenotype of these 10 novel truncating mutations was clinically documented within their kindreds. Important variability was observed in the phenotype. Interestingly, we noted that a mutation (487insT) localized at the boundary of the 5' attenuated APC phenotype region in two unrelated families resulted in classical polyposis. A clear-cut genotype-phenotype correlation could be drawn in only two instances. In one family, a 4684insA mutation led to a mild polyposis associated with early inherited osteomas and, in the family bearing the double mutation (Z1625H + 4897delC), the phenotype was obviously a 3' attenuated type. Our data illustrate the wide genetic and phenotypic heterogeneity of this condition between and within the families, making the establishment of correlations complex and any prediction in this disease difficult, although targeting the mutation site may be helpful in some specific cases.     

Microsatellite instability in early onset and familial colorectal cancer

Hereditary non-polyposis colorectal cancer syndrome (HNPCC) is often considered to be the most common form of inherited colorectal cancer, although its precise incidence is unknown. The clinical diagnosis of HNPCC relies on a combination of family history and young age of onset of colorectal cancer, but as many familial aggregations of colorectal cancer do not fulfil the strict diagnostic criteria, HNPCC might be underdiagnosed. The majority of HNPCC families have germline mutations in mismatch repair (MMR) genes, such as MSH2 or MLH1, so that HNPCC cancers characteristically exhibit DNA replication errors (RERs) at microsatellite loci. Although an RER positive phenotype in tumours can also result from somatic mutations in an MMR gene, the prevalence of RER + tumours should provide a maximum estimate of the incidence of germline MMR gene mutations in patients with early onset and familial colorectal cancer. We investigated colorectal cancers for RERs from (1) a population based study of 33 patients with colorectal cancer aged 45 years or less, (2) 65 kindreds with familial colorectal cancer which only partially fulfilled the criteria for the diagnosis of HNPCC, and (3) 18 cancers from 12 HNPCC kindreds. Seven of 33 patients (21%) with colorectal cancer aged 45 years or less had an RER + cancer, with only two of these having a clear family history of HNPCC. A greater proportion of RER + tumours (5/7) occurred proximal to the splenic flexure than RER - tumours (4/26; chi2 = 6.14, p < 0.025). RERs were detected in all 18 cancers from HNPCC patients but in only six of 65 non-HNPCC familial colorectal cancer kindreds (9%; chi2 = 52.2, p < 0.0005). These findings suggest that most cancers in patients diagnosed at 45 years of age or less and familial aggregations of colorectal cancer which do not fulfil HNPCC diagnostic criteria do not have germline mutations in MSH2 and MLH1. Hence population screening for germline mutations in these genes is unlikely to be an efficient strategy for identifying people at high risk of developing colorectal cancer.     

Community participation and appropriate technology in the early diagnosis of human hydatidosis

Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations at the PKD1 locus in most families. This locus has been assigned to the short arm of chromosome 16 by linkage analysis. It has been estimated that approximately 5% of families have a disease that does not map to this locus and most of these families have clinical features indistinguishable from the disease caused by PKD1 mutations. We report a large three-generation Caucasian family from Northern Ireland with ADPKD in whom all affected individuals (age range 22-68) were normotensive and only the two eldest had mild renal impairment. Linkage was excluded between the disease and both the alpha-globin gene complex and the microsatellite marker D16S283. This family confirms that phenotypic heterogeneity exists between unlinked families and that certain non-PKD1 mutations cause mild disease expression. Many such individuals may therefore remain undetected and the incidence of families with ADPKD who have non-PKD1 mutations may be greater than previously estimated.     

Genotype-phenotype correlations in attenuated adenomatous polyposis coli

Germ-line mutations of the tumor suppressor APC are implicated in attenuated adenomatous polyposis coli (AAPC), a variant of familial adenomatous polyposis (FAP). AAPC is recognized by the occurrence of <100 colonic adenomas and a later onset of colorectal cancer (age >40 years). The aim of this study was to assess genotype-phenotype correlations in AAPC families. By protein-truncation test (PTT) assay, the entire coding region of the APC gene was screened in affected individuals from 11 AAPC kindreds, and their phenotypic differences were examined. Five novel germ-line APC mutations were identified in seven kindreds. Mutations were located in three different regions of the APC gene: (1) at the 5' end spanning exons 4 and 5, (2) within exon 9, and (3) at the 3' distal end of the gene. Variability in the number of colorectal adenomas was most apparent in individuals with mutations in region 1, and upper-gastrointestinal manifestations were more severe in them. In individuals with mutations in either region 2 or region 3, the average number of adenomas tended to be lower than those in individuals with mutations in region 1, although age at diagnosis was similar. In all AAPC kindreds, a predominance of right-sided colorectal adenomas and rectal polyp sparing was observed. No desmoid tumors were found in these kindreds. Our data suggest that, in AAPC families, the location of the APC mutation may partially predict specific phenotypic expression. This should help in the design of tailored clinical-management protocols in this subset of FAP patients.     

Linkage of Wolfram syndrome to chromosome 4p16.1 and evidence for heterogeneity

Wolfram syndrome (DIDMOAD syndrome; MIM 222300) is an autosomal recessive neurodegenerative disorder characterized by juvenile-onset diabetes mellitus and bilateral optic atrophy. Previous linkage analysis of multiply affected families indicated that the gene for Wolfram syndrome is on chromosome 4p, and it produced no evidence for locus heterogeneity. We have investigated 12 U.K. families with Wolfram syndrome, and we report confirmation of linkage to chromosome 4p, with a maximum two-point LOD score of 4.6 with DRD5, assuming homogeneity, and of 5.1, assuming heterogeneity. Overlapping multipoint analysis using six markers at a time produced definite evidence for locus heterogeneity: the maximum multipoint LOD score under homogeneity was <2, whereas when heterogeneity was allowed for an admixture a LOD of 6.2 was obtained in the interval between D4S432 and D4S431, with the peak close to the marker D4S3023. One family with an atypical phenotype was definitely unlinked to the region. Haplotype inspection of the remaining 11 families, which appear linked to chromosome 4p and had typical phenotypes, revealed crossover events during meiosis, which also placed the gene in the interval D4S432 and D4S431. In these families no recombinants were detected with the marker D4S3023, which maps within the same interval.     

Multilocus linkage identifies two new loci for a mendelian form of stroke, cerebral cavernous malformation, at 7p15-13 and 3q25.2-27

Cerebral cavernous malformation (CCM) is a Mendelian model of stroke, characterized by focal abnormalities in small intracranial blood vessels leading to hemorrhage and consequent strokes and/or seizures. A significant fraction of cases is inherited as an autosomal dominant trait with incomplete penetrance. Among Hispanic Americans, virtually all CCM is attributable to a founder mutation localized to 7q ( CCM1 ). Recent analysis of non-Hispanic Caucasian kindreds, however, has excluded linkage to 7q in some, indicating at least one additional CCM locus. We now report analysis of linkage in 20 non-Hispanic Caucasian kindreds with familial CCM. In addition to linkage to CCM1, analysis of linkage demonstrates linkage to two new loci, CCM2 at 7p13-15 and CCM3 at 3q25.2-27. Multilocus analysis yields a maximum lod score of 14.11, with 40% of kindreds linked to CCM1, 20% linked to CCM2 and 40% linked to CCM3, with highly significant evidence for linkage to three loci (linkage to three loci supported with an odds ratio of 2.6 x 10(5):1 over linkage to two loci and 1.6 x 10(9):1 over linkage to one locus). Multipoint analysis among families with high posterior probabilities of linkage to each locus refines the locations of CCM2 and CCM3 to approximately 22 cM intervals. Linkage to these three loci can account for inheritance of CCM in all kindreds studied. Significant locus-specific differences in penetrance are identified. These findings have implications for genetic testing of this disorder and represent an important step toward identification of the molecular basis of this disease.     

Germline BRCA1 mutations and loss of the wild-type allele in tumors from families with early onset breast and ovarian cancer

The BRCA1 gene on human chromosome 17q21 is responsible for an autosomal dominant syndrome of inherited early onset breast/ovarian cancer. It is estimated that women harboring a germline BRCA1 mutation incur an 85% lifetime risk of breast cancer and a greatly elevated risk of ovarian cancer. The BRCA1 gene has recently been isolated and mutations have been found in the germline of affected individuals in linked families. Previous studies of loss of heterozygosity (LOH) in breast tumors have been carried out on sporadic tumors derived from individuals without known linkage to BRCA1 and on tumors from linked families. Loss of large regions of chromosome 17 has been observed, but these LOH events could not be unequivocally ascribed to BRCA1. We have studied 28 breast and 6 ovarian tumors from families with strong evidence for linkage between breast cancer and genetic markers flanking BRCA1. These tumors were examined for LOH using genetic markers flanking and within BRCA1, including THRA1, D17S856, EDH17B1, EDH17B2, and D17S183. Forty-six percent (16/34) of tumors exhibit LOH which includes BRCA1. In 8 of 16 tumors the parental origin of the deleted allele could be determined by evaluation of haplotypes of associated family members; in 100% of these cases, the wild-type allele was lost. In some of these families germline mutations in BRCA1 have been determined; analyses of tumors with LOH at BRCA1 have revealed that only the disease-related allele of BRCA1 was present. These data strongly support the hypothesis that BRCA1 is a tumor suppressor gene.     

HIV-1 viral load: comparative evaluation of three commercially available assays in Argentina

Autosomal recessive nonsyndromic hearing loss (ARNSHL) is the most common form of hereditary hearing impairment (HHI). To date, 16 different loci have been reported, making ARNSHL an extremely heterogeneous disorder. One of these loci, DFNB4, was mapped to a 5-cM interval of 7q31 in a large Middle-Eastern Druze family. This interval also includes the gene for Pendred syndrome. We report on three new families with HHI from the Madras region of southern India that demonstrate linkage to 7q. Their pedigrees are compatible with autosomal recessive inheritance. Furthermore, the largest family identifies a novel locus (DFNB17) telomeric to the DFNB4 and Pendred intervals. A 3-cM region of homozygosity by descent between markers D7S486 and D7S2529 is present in all affected individuals in this family and generates a multipoint LOD score of 4.24. The two other families map to the previously reported DFNB4 region but have insufficient power to attain significant LOD scores. However, mutations in the Pendred syndrome gene are present in one of these families.     

Unusual involvement of bone in primary systemic amyloidosis

Vesicoureteric reflux (VUR) is a common childhood condition characterised by regurgitation of urine from the bladder to the kidney. It is the commonest cause of end stage renal failure in children and an important cause in adults. Primary VUR is often familial, suggesting that genetic factors play an important role in its aetiology. Recently, VUR was observed as part of a syndrome, involving optic nerve colobomas and renal anomalies, caused by mutations of the PAX2 gene. PAX2 is a member of the paired box family of genes and is expressed in the ureteric bud and differentiating nephrogenic mesenchyme of the developing kidney. PAX2 has been shown to play a critical role in the development of both the kidney and the ureter. The occurrence of VUR in one family with the PAX2 mutation, and the expression pattern of PAX2 in developing ureteric bud, strongly suggested that PAX2 could be the cause of primary familial VUR. Single strand conformational polymorphism (SSCP) analysis of 23 affected subjects in eight families with primary familial VUR showed no alterations in exons 2-5 of the PAX2 gene. In addition, a polymorphic dinucleotide repeat marker located within the PAX2 gene segregated independently of the disease trait in one large family who primarily had VUR or reflux nephropathy. These results suggest that PAX2 is not a major cause of primary familial reflux.     

Analysis of the p16 gene, CDKN2, in 17 Australian melanoma kindreds

CDKN2 has been implicated as a melanoma susceptibility gene in some kindreds with a family history of this disease. Mutation analysis of CDKN2 in 17 familial melanoma Australian kindreds revealed a paucity of exon mutations and none of the previously described disease-related mutations. One novel germline mutation was found in exon one, Arg24Pro, which segregates with melanoma in 1/17 kindreds. Two previously described polymorphisms, Ala148Thr and a base change at nucleotide 540 were detected and one novel polymorphism in the untranslated region of exon 3 (nucleotide 580) was also found. Together with other recent reports, these findings provide support for CDKN2 as a susceptibility locus for familial melanoma but suggest that other loci are involved in some hereditary melanoma kindreds.