Analysis of 133 meioses places the genes for nevoid basal cell carcinoma (Gorlin) syndrome and Fanconi anemia group C in a 2.6-cM interval and contributes to the fine map of 9q22.3

Odontogenic Keratocyst: A Case Series of five Patients

During the time period of August 2009 to August 2010, five cases of odontogenic keratocyst were admitted and treated under the care of Department of Otorhinolaryngology, MGMC and RI, Puducherry. Patients came to the ENT OPD with history of swelling in the cheek region, nasal obstruction, numbness in the upper alveolar region. On examination diffuse swelling of size 7 × 3 cm in one patient and size of 5 × 3 cm in two patients, and other two patients size of 6 × 3 cm present in the maxillary region with ill defined borders, the swelling was firm in consistency, no warmth, non tender. Anterior rhinoscopy reveals mass pushing the lateral wall medially, septum pushed to opposite side, mucopus present in nasal cavity, airway reduced on the side of swelling. On examination of oral cavity, a small granulation of size 1.0 × 0.5 cm present in two patient and swelling of size 1.5 × 1.0 cm seen in two patients in vestibule, no swelling in one patient and swelling of size 3 × 2 cm seen in hard palate of two patients and no swelling in three patients, no loosening of tooth seen in all patients. X-ray PNS reveals maxillary hazziness, diagnostic nasal endoscopy reveals lateral wall of nose pushed medially and septum pushed to opposite side. FNAC reveals resolving inflammatory aspirate in one patient, few macrophages seen in two of patients, few keratinocytes seen in two of the patients. CT nose and PNS revealed a large cystic lesion with erosion of anterior and medial wall and floor of maxilla in relation to the root of the last molar tooth in two patients and there is erosion of anterior and medial wall in other three patients. A combined endonasal and external sublabial (Caldwell-luc) approach was performed in four patients and the cystic lesion was removed and in other one patient only endonasal approach was done and cystic lesion was removed and sent for biopsy. Biopsy sent for HPE revealed odontogenic keratocyst.

Prevalence, treatment and recurrence of odontogenic keratocyst in central India

OBJECTIVE

The present study aimed to evaluate the prevalence, sex predilection and treatment modalities of OKC in Central India.

MATERIALS AND METHODS

Total 2900 patients were screened from various hospitals and centers. Age of patients and site of lesion was recorded. OKC was classified into initial, moderate and advanced depending on the radiological involvement and treatment modalities given with respect to the extent of the OKC.

RESULT

Total 49 patients were diagnosed with the presence of OKC. It was found that mostly it is common in 3rd and 4th decades, with the mean age 28 years in males and 31 years in females. The most common site of occurrence was angle of mandible and the ramus region. The treatment of OKC, on the basis of the radiographic classification, gives excellent results with minimum recurrences.

CONCLUSION

The most common age and site occurrence was relevant with that of previous studies (Browne, Br Dent J 128(5):225-231, 1970, Chen and Lin, Gaoxiong Yi Xue Ke Xue Za Zhi 2(9):601-607, 1986). This study concluded by considering multicentric incidence, prevalence of OKC in Central India, that the population should be screened for OKC. The screening should be done by clinical, radiological and histopathological. While screening all the parameters should be considered to diagnose and treat the patients for the prevention of morbidity.

The elusive multiple self-healing squamous epithelioma (MSSE) gene: further mapping, analysis of candidates, and loss of heterozygosity

The MSSE gene predisposes to multiple invasive but self-healing skin tumours (multiple self-healing epitheliomata). MSSE was previously mapped to chromosome 9q22-q31 and a shared haplotype in affected families suggested a founder mutation. We have refined the MSSE critical region (<1 cM, <1 Mb) between the zinc-finger gene ZNF169 and the Fanconi anaemia gene FANCC. By genetic mapping we have excluded ZNF169 and FANCC as well as PTCH (PATCHED) and TGFBR1 (transforming growth factor beta receptor type-1) genes. The CDC14B cell cycle phosphatase gene also lies in the region but screening of the complete coding region revealed no mutation in MSSE patients. Somatic cell hybrids created by haploid conversion of an MSSE patient's cells enabled screening of the MSSE chromosome 9 and showed no CDC14B deletion or mutation that abrogates CDC14B mRNA expression. Thus, CDC14B is unlikely to be the MSSE gene. We also report the first molecular analysis of MSSE tumours showing loss of heterozygosity of the MSSE region, with loss of the normal allele, providing the first evidence that MSSE is a tumour suppressor gene.

Perinatal findings and molecular cytogenetic analyses ofde novo interstitial deletion of 9q (9q22.3→q31.3) associated with Gorlin syndrome

OBJECTIVES

To present the perinatal findings and the molecular cytogenetic analyses of a de novo interstitial deletion of 9q (9q22.3-->q31.3) associated with Gorlin syndrome.

METHODS

Amniocentesis was performed at 18 weeks' gestation on a 27-year-old woman at a community hospital because of a high Down syndrome risk of 1/178, a low maternal serum alpha-fetoprotein (MSAFP) level of 0.66 multiples of the median (MoM), and a high maternal serum human chorionic gonadotrophin (MShCG) level of 3.13 MoM. The karyotype was initially determined to be 46,XY. However, fetal macrocephaly and overgrowth were found at 30 weeks' gestation. Postnatally, the infant manifested characteristic features of Gorlin syndrome. High-resolution chromosomal bandings of the peripheral blood lymphocytes, polymorphic DNA marker analysis to determine the parental origin of the deletion, array comparative genomic hybridization (CGH) to determine the extent of the chromosomal deletion, and fluorescence in situ hybridization (FISH) to determine the deletion of the PTCH gene were performed.

RESULTS

The 850-band level of resolution showed an interstitial deletion of 9q (9q22.3-->q31.3). The parental karyotypes were normal. The karyotype of the proband was 46,XY,del(9)(q22.3q31.3)de novo. Polymorphic DNA marker analysis revealed that the deletion was of paternal origin. Array CGH revealed that the deleted region was about 12 Mb, encompassing the segment from 9q22.32 to 9q31.3. FISH analysis using the BAC probe RP11-34D4 and the probe RP11-43505 indicated the deletion of the PTCH gene.

CONCLUSIONS

Fetuses with an interstitial deletion of 9q (9q22.3-->q31.3) may be associated with a low level of MSAFP and a high level of MShCG in the second trimester, and sonographic findings of overgrowth and macrocephaly in the third trimester.

Interstitial deletion 9q22.32-q33.2 associated with additional familial translocation t(9;17)(q34.11;p11.2) in a patient with Gorlin-Goltz syndrome and features of Nail-Patella syndrome

The phenotype of Gorlin-Goltz syndrome or basal cell nevus syndrome (BCNS, #109400, OMIM), a Mendelian trait due to PTCH mutations has been reported in a few cases of interstitial deletion of chromosome 9q. We present an 11-year-old girl with clinical features consistent with BCNS including bridging of sella turcica, biparietal bossing, downward slanting palpebral fissures, mandible prognathism, pectus excavatum, thumb abnormalities, occult spina bifida at L5-S4, numerous basal cell nevi, and single basal cell carcinoma. Cytogenetic analysis using high-resolution banding techniques and fluorescence in situ hybridization (FISH) revealed interstitial chromosome deletion 9q22.32-q33.2 involving the PTCH gene as a secondary breakage event to a chromosome translocation t(9;17)(q34.1;p11.2)mat. Further FISH studies showed the translocation breakpoint on 9q34.11 maps proximal to ABL, between the BAC clone RP11-88G17 and the LMX1B gene. The latter gene encodes a transcription factor, in which loss of function mutations are responsible for the nail-patella syndrome (NPS, #161200 OMIM). Interestingly, some features of our proband (e.g., bilateral patellar dysplasia and abnormal clavicular shape), as well as her healthy sister who carries the same translocation, are also found in patients with NPS. The chromosome 17p11.2 breakpoint maps in the Smith-Magenis syndrome common deletion region, within two overlapping BAC clones, CTD-2354J3 and RP11-311F12.

UV-specific p53 and PTCH mutations in sporadic basal cell carcinoma of sun-exposed skin

UVB irradiation is known to produce DNA damage at mutation hotspots in the p53 tumor suppressor gene, leading to the development of skin cancers. Mutations in the PTCH tumor suppressor gene, which is known to be responsible for the development of nevoid basal cell carcinoma syndrome, have also been identified in sporadic basal cell carcinomas (BCCs). We describe the case of an 80-year-old welder in whom 3 novel p53 mutations, as well as UV-specific PTCH mutations, were detected in two BCC samples from sun-exposed skin. The simultaneous presence of UV-specific p53 and PTCH mutations in the same BCC sample has not previously been reported.

The IVS4 + 4 A to T mutation of the Fanconi anemia geneFANCC is not associated with a severe phenotype in Japanese patients

Fanconi anemia (FA) is an autosomal recessive disease characterized by congenital anomalies, aplastic anemia, and a susceptibility to leukemia. There are at least 8 complementation groups (A through H). Extensive analyses of the FA group C gene FANCC in Western countries revealed that 10% to 15% of FA patients have mutations of this gene. The most common mutation is IVS4 + 4 A to T (IVS4), a splice mutation in intron 4, which has been found only in patients of Ashkenazi Jewish ancestry. When we screened 29 Japanese patients (20 unrelated patients and 4 families) using polymerase chain reaction–single strand conformation polymorphism, we found 8 unrelated patients homozygous for IVS4. This is apparently the first non–Ashkenazi-Jewish population for whom this mutation has been detected. The Ashkenazi Jewish patients homozygous for IVS4 have a severe phenotype, in comparison with other FA patients. Our analyses of Japanese patients indicate no significant difference between IVS4 homozygotes and other patients with regard to severity of a clinical phenotype. Thus, ethnic background may have a significant effect on a clinical phenotype in FA patients carrying the same mutation.

Developmental genes and cancer: role of patched in basal cell carcinoma of the skin

Many genes originally identified because of their role in embryonic development are also important in postnatal control of cell growth and differentiation. Mutations in some of these genes have been shown to cause cancer. Basal cell carcinoma (BCC) of the skin is the most common cancer in humans. More than 750000 new cases are diagnosed annually, and the incidence is rising. BCCs are slow-growing, locally invasive tumors that rarely metastasize but can result in extensive morbidity through local recurrence and tissue destruction. Epidemiologic studies suggest that sunlight (particularly UVB radiation) is a strong risk factor for BCC formation, although other factors are also involved. The nevoid basal cell carcinoma syndrome (NBCCS), a rare genetic disorder, is characterized by predisposition to BCCs and other tumors as well as to a wide range of developmental defects. NBCCS maps to chromosome 9q22.3, and loss of heterozygosity at this site in both sporadic and hereditary BCCs suggests that it functions as a tumor suppressor. The gene for NBCCS was recently cloned and is the human homologue of the Drosophila gene "patched." Genetic studies in Drosophila show that patched is part of the hedgehog signaling pathway, which is important in determining embryonic patterning and cell fate in multiple structures of the developing embryo. Human patched is mutated in both hereditary and sporadic BCCs, and inactivation of this gene is probably a necessary, if not sufficient, step for BCC formation. Delineation of the biochemical pathway in which patched functions may lead to rational medical therapy for BCCs and possibly for other tumors associated with NBCCS.

Characterization of a YAC contig containing the NBCCS locus and a novel Kruppel-type zinc finger sequence on chromosome segment 9q22.3

Gorlin's syndrome or nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterized by a familial or hereditary predisposition to basal cell carcinomas (generally multiple and of early onset), odontogenic keratocysts (jaw cysts), palmar and plantar pits, a wide variety of developmental defects, as well as cancers such as medulloblastomas and ovarian fibromas. The gene for NBCCS has been mapped to human chromosome region 9q22.1-q31 by linkage analysis and by cytogenetic evidence of deletions in this region in patients with the syndrome. This is supported by loss of heterozygosity in tumors of polymorphic marker loci flanked by D9S197 and D9S180. We have utilized sequence tagged site (STS) mapping and somatic cell hybrid panel analysis to construct two overlapping yeast artificial chromosome (YAC) contigs spanning this region of the genome. We used the YAC contigs to identify a new zinc finger gene containing a highly informative microsatellite locus.

cDNA cloning of a novel WD repeat protein mapping to the 9q22.3 chromosomal region

To identify expressed sequences from the candidate genomic region of the nevoid basal cell carcinoma syndrome (9q22.3), the CpG island rescue PCR methodology was employed on the yeast artificial chromosome (YAC) ICI-8AD8 that contains microsatellite marker D9S180. A positive clone (IR10, size 350 bp) was isolated by screening a human epidermal cDNA library with the island rescue PCR products and mapped back to the 9q22.3 region. To obtain additional sequence information from IR10, the rapid amplification of cDNA ends (RACE) methodology was employed. Within the longest IR10 RACE product, two segments having similarities with coronin, a G-like and actin-binding protein of Dictyostelium discoideum, as well as with p57, a recently cloned human actin-binding protein, were revealed. In fact, these two segments have properties of typical exons, suggesting that the RACE products and clone IR10 represent unspliced pre-mRNAs. Using the RACE methodology with primers originating from these two exons, it was shown that they splice together and the sequences corresponding to the processed IR10 mRNA were revealed. This mRNA maps back to 9q22.3 and furthermore was found to code for a novel protein composed of 525 amino acids and containing five WD repeats. The presence of the WD repeat motif, considered to function in protein-protein interactions, implies that the new protein might have a role in intracellular signaling. Moreover, Northern analysis indicated that, in addition to epidermis, the brain is a tissue with relatively high levels of expression of this gene. Finally, Southern analysis showed a functional conservation of the WD repeat protein in various species.

Differential allele loss on chromosome 9q22.3 in human non-melanoma skin cancer

Familial predisposition to basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) of the skin are apparent in the autosomal dominant syndromes naevoid basal cell carcinoma syndrome (NBCCS) and multiple self-healing squamous epitheliomata (MSSE) respectively. The gene responsible for NBCCS has been proposed to be a tumour-suppressor gene and is mapped to the same 2 Mb interval on 9q22.3 as the MSSE gene ESS1. In an attempt to further map the NBCCS gene, we have examined loss of heterozygosity (LOH) in 16 sporadic BCCs and two familial BCCs using microsatellite markers located within the candidate gene region. The overall frequency of LOH observed was 67% in the BCCs and partial or interstitial deletions were found in eight tumours, with the highest LOH frequency at markers D9S280, D9S287 and D9S180. To determine if the same genomic region also shows frequent LOH in tumours with a squamous phenotype, we have examined 11 SCCs, four actinic keratoses and 13 cases of Bowen's disease for LOH at 9q22.3. An overall LOH frequency of 50% was observed at D9S180, and occurred in all types of squamous tumours. In contrast, a much lower LOH frequency of only 6% was found at the D9S287 locus. Our observation of different patterns of LOH at 9q22.3 in sporadic BCCs and SCCs implies that more than one tumour-suppressor gene might be located in this genomic region.

Human homolog of patched, a candidate gene for the basal cell nevus syndrome

The basal cell nevus syndrome (BCNS) is characterized by developmental abnormalities and by the postnatal occurrence of cancers, especially basal cell carcinomas (BCCs), the most common human cancer. Heritable mutations in BCNS patients and a somatic mutation in a sporadic BCC were identified in a human homolog of the Drosophila patched (ptc) gene. The ptc gene encodes a transmembrane protein that in Drosophila acts in opposition to the Hedgehog signaling protein, controlling cell fates, patterning, and growth in numerous tissues. The human PTC gene appears to be crucial for proper embryonic development and for tumor suppression.

Mutations of the human homolog of Drosophila patched in the nevoid basal cell carcinoma syndrome

The nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterized by multiple basal cell carcinomas (BCCs), pits of the palms and soles, jaw keratocysts, a variety of other tumors, and developmental abnormalities. NBCCS maps to chromosome 9q22.3. Familial and sporadic BCCs display loss of heterozygosity in this region, consistent with the gene being a tumor suppressor. A human sequence (PTC) with strong homology to the Drosophila segment polarity gene, patched, was isolated from a YAC and cosmid contig of the NBCCS region. Mutation analysis revealed alterations of PTC in NBCCS patients and in related tumors. We propose that a reduction in expression of the patched gene can lead to the developmental abnormalities observed in the syndrome and that complete loss of patched function contributes to transformation of certain cell types.

The genetics of human skin diseases

Molecular genetic analyses during the past half-decade have brought unexpected insights into the molecular defects underlying a wide variety of abnormal skin phenotypes. Highlights of the efforts in the past year include the identification of mutations in an epidermal transglutaminase gene in lamellar ichthyosis as well as mutations in an additional five keratin genes causing four different abnormal phenotypes, and mutations in beta 4 integrin and bullous pemphigoid antigen 2 genes in junctional epidermolysis bullosa and in the p16NK-4a gene in 50% of kindreds with familial melanoma.

A mammalian patched homolog is expressed in target tissues of sonic hedgehog and maps to a region associated with developmental abnormalities

Drosophila patched is a segment polarity gene required for the correct patterning of larval segments and imaginal discs during fly development and has a close functional relationship with hedgehog. We have isolated a complete human PATCHED cDNA sequence, which encodes a putative protein of 1296 amino acids, and displays 39% identity and 60% similarity to the Drosophila PATCHED protein. Hydropathy analysis suggests that human PATCHED is an integral membrane protein with a pattern of hydrophobic and hydrophilic stretches nearly identical to that of Drosophila patched. In the developing mouse embryo, patched is initially detected within the ventral neural tube and later in the somites and limb buds. Expression in the limb buds is restricted to the posterior ectoderm surrounding the zone of polarizing activity. The results show that patched is expressed in target tissues of sonic hedgehog, a murine homolog of Drosophila hedgehog suggesting that patched/hedgehog interactions have been conserved during evolution. Human PATCHED maps to human chromosome 9q22.3, the candidate region for the nevoid basal cell carcinoma syndrome. Patched expression is compatible with the congenital defects observed in the nevoid basal cell carcinoma syndrome.

Investigation of chromosome 9q22.3-q31 DNA marker loss in odontogenic keratocysts

Multiple basal cell carcinomas and odontogenic keratocysts of the jaws are a feature of the inherited naevoid basal cell carcinoma syndrome (NBCCS), although both occur more commonly as single, sporadic cases. The NBCCS gene has been mapped to chromosome 9q22.3-q31 and loss of heterozygosity for DNA markers from this region has been observed in familial and sporadic basal cell carcinomas. Based on these observations, we undertook a pilot study to determine if a similar pattern of chromosome loss occurs in odontogenic keratocysts. DNA extracted from microdissected odontogenic keratocyst epithelium was examined for loss of heterozygosity for six polymorphic DNA markers mapping to human chromosome 9q22.3-q31. Allelotype loss was detected in epithelium from three, single, sporadic odontogenic keratocysts. These results implicate homozygous inactivation of the NBCCS gene in the initiation and progression of the odontogenic keratocyst.