Interstitial deletion of chromosome 9, int del(9)(9q22.31-q31.2), including the genes causing multiple basal cell nevus syndrome and Robinow/brachydactyly 1 syndrome

Basal cell nevus syndrome: From DNA to therapeutics

Basal cell nevus syndrome, also known as Gorlin syndrome, is a hereditary cancer syndrome associated with multiple basal cell carcinomas, congenital defects, and nondermatologic tumors. This disease is autosomal dominant with variable expressivity and is caused by abnormalities in the sonic hedgehog signaling pathway. Management requires a multidisciplinary approach and should include the biopsychosocial needs of patients and their families. Genetic testing is necessary to confirm an unclear diagnosis, evaluate at-risk relatives, and assist with family planning.

A familial case of overgrowth syndrome caused by a 9q22.3 microdeletion in a mother and daughter

Microdeletions in the 9q22.3 chromosomal region can cause macrosomia with characteristic features, including prenatal-onset overgrowth, metopic craniosynostosis, hydrocephalus, developmental delay, and intellectual disability, in addition to manifestations of nevoid basal cell carcinoma syndrome (NBCCS). Haploinsufficiency of PTCH1 may be responsible for accelerated overgrowth, but the mechanism of macrosomia remains to be elucidated. We report a familial case with a 9q22.3 microdeletion, manifesting with prenatal-onset overgrowth in a mother and post-natal overgrowth in her daughter. Although both were clinically diagnosed with NBCCS, they had characteristic features of 9q22.3 microdeletion, especially the daughter. Microarray comparative genomic hybridization analysis revealed a 4.0 Mb deletion of chromosome 9q22.3 in both individuals. Among the 11 reported patients of overgrowth and/or macrosomia, a 550 Kb region encompassing PTCH1, C9orf3, FANCC, and 5 miRNAs is the most commonly deleted region. The let-7 family miRNAs, which are involved in diverse cellular processes including growth and tumor processes, were identified in the deleted regions in 10 of 11 patients. Characteristic features of 9q22.3 microdeletion might be associated with decreased expression of let-7.

Basal cell nevus syndrome (Gorlin syndrome): genetic insights, diagnostic challenges, and unmet milestones

In this article, we present three clinical case reports on Basal Cell Nevus Syndrome (Gorlin Syndrome). Gorlin syndrome is an inherited medical condition with challenges that manifest in multiple body systems and complicate early diagnosis. We examine the epidemiology of the disease and benefits of genetic testing, molecular pathophysiology, and advancement in the molecular-based therapy of Basal Cell Nevus syndrome. The goal of this paper is to shed light on both unmet challenges and advancements in the management of Gorlin syndrome and to provide a new clinical perspective and guidance for future research. Furthermore, the FDA approved Hedgehog pathway inhibitors Vismodegib and Sonidegib designed for advanced basal cell carcinoma have opened a new door for treatment that may ultimately decrease the number of surgeries for a patient with Gorlin syndrome. The role of these agents in syndromic odontogenic keratocyst has not been studied extensively, but one study found that hedgehog pathway inhibitors decrease the size of syndromic odontogenic keratocyst. Ideal surgical treatment that balances low recurrence rates with low impact on one's quality of life for syndromic odontogenic keratocyst is another unanswered question for oral and maxillofacial surgeons. Per survey studies, treatment options practiced for syndromic odontogenic keratocyst range from marsupialization to segmental osteotomy. Future studies performed should take a comprehensive long-term approach with at least three years of follow-up in order to determine the most appropriate treatment.

Multiple tumor types including leiomyoma and Wilms tumor in a patient with Gorlin syndrome due to 9q22.3 microdeletion encompassing the PTCH1 and FANC-C loci

Gorlin syndrome or nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant condition mainly characterized by the development of mandibular keratocysts which often have their onset during the second decade of life and/or multiple basal cell carcinoma (BCC) normally arising during the third decade. Cardiac and ovarian fibromas can be found. Patients with NBCCS develop the childhood brain malignancy medulloblastoma (now often called primitive neuro-ectodermal tumor [PNET]) in 5% of cases. The risk of other malignant neoplasms is not clearly increased, although lymphoma and meningioma can occur in this condition. Wilms tumor has been mentioned in the literature four times. We describe a patient with a 10.9 Mb 9q22.3 deletion spanning 9q22.2 through 9q31.1 that includes the entire codifying sequence of the gene PTCH1, with Wilms tumor, multiple neoplasms (lung, liver, mesenteric, gastric and renal leiomyomas, lung typical carcinoid tumor, adenomatoid tumor of the pleura) and a severe clinical presentation. We propose including leiomyomas among minor criteria of the NBCCS.

Heterozygous tandem duplication within the PTCH1 gene results in nevoid basal cell carcinoma syndrome

Nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterized by developmental defects and tumorigenesis. The gene responsible for NBCCS is PTCH1. Using multiplex ligation-dependent probe amplification, we identified a heterozygous tandem duplication within the PTCH1 gene in a 14-year-old girl with typical NBCCS. We have sequenced the chromosomal breakpoint and determined the duplication as tandem in orientation and 18,814 bp in size. The fusion occurred between non-repetitive elements with an overlap of three nucleotides. The duplicated segment began at exon 10 and ended at intron 17. Subsequent analysis of cDNA from the patient showed the expression of mutant mRNA species containing a duplicated segment spanning exons 11-17, resulting in a frameshift and premature stop codon. This is the first reported case of NBCCS due to a tandem multiexon duplication of PTCH1 representing a novel mechanism leading to the NBCCS phenotype, and highlights the importance of copy number analysis as an adjunct to exon sequencing in identifying infrequent mutational events in PTCH1.

Microdeletion 9q22.3 syndrome includes metopic craniosynostosis, hydrocephalus, macrosomia, and developmental delay

Basal cell nevus syndrome (BCNS), also known as Gorlin syndrome (OMIM #109400) is a well-described rare autosomal dominant condition due to haploinsufficiency of PTCH1. With the availability of comparative genomic hybridization arrays, increasing numbers of individuals with microdeletions involving this locus are being identified. We present 10 previously unreported individuals with 9q22.3 deletions that include PTCH1. While 7 of the 10 patients (7 females, 3 males) did not meet strict clinical criteria for BCNS at the time of molecular diagnosis, almost all of the patients were too young to exhibit many of the diagnostic features. A number of the patients exhibited metopic craniosynostosis, severe obstructive hydrocephalus, and macrosomia, which are not typically observed in BCNS. All individuals older than a few months of age also had developmental delays and/or intellectual disability. Only facial features typical of BCNS, except in those with prominent midforeheads secondary to metopic craniosynostosis, were shared among the 10 patients. The deletions in these individuals ranged from 352  kb to 20.5  Mb in size, the largest spanning 9q21.33 through 9q31.2. There was significant overlap of the deleted segments among most of the patients. The smallest common regions shared among the deletions were identified in order to localize putative candidate genes that are potentially responsible for each of the non-BCNS features. These were a 929  kb region for metopic craniosynostosis, a 1.08  Mb region for obstructive hydrocephalus, and a 1.84  Mb region for macrosomia. Additional studies are needed to further characterize the candidate genes within these regions.

9q22 Deletion--first familial case

Background

Only 29 cases of constitutional 9q22 deletions have been published and all have been sporadic. Most associate with Gorlin syndrome or nevoid basal cell carcinoma syndrome (NBCCS, MIM #109400) due to haploinsufficiency of the PTCH1 gene (MIM *601309).

Methods and Results

We report two mentally retarded female siblings and their cognitively normal father, all carrying a similar 5.3 Mb microdeletion at 9q22.2q22.32, detected by array CGH (244 K). The deletion does not involve the PTCH1 gene, but instead 30 other gene,s including the ROR2 gene (MIM *602337) which causing both brachydactyly type 1 (MIM #113000) and Robinow syndrome (MIM #268310), and the immunologically active SYK gene (MIM *600085). The deletion in the father was de novo and FISH analysis of blood lymphocytes did not suggest mosaicism. All three patients share similar mild dysmorphic features with downslanting palpebral fissures, narrow, high bridged nose with small nares, long, deeply grooved philtrum, ears with broad helix and uplifted lobuli, and small toenails. All have significant dysarthria and suffer from continuous middle ear and upper respiratory infections. The father also has a funnel chest and unilateral hypoplastic kidney but the daughters have no malformations.

Conclusions

This is the first report of a familial constitutional 9q22 deletion and the first deletion studied by array-CGH which does not involve the PTCH1 gene. The phenotype and penetrance are variable and the deletion found in the cognitively normal normal father poses a challenge in genetic counseling.

Further delineation of 9q22 deletion syndrome associated with basal cell nevus (Gorlin) syndrome: report of two cases and review of the literature

Basal cell nevus syndrome (BCNS; Gorlin syndrome) is an autosomal dominant disorder, characterized by a predisposition to neoplasms and developmental abnormalities. BCNS is caused by mutations in the human homolog of the Drosophila patched gene-1, PTCH1, which is mapped on chromosome 9q22.3. Nonsense, frameshift, in-frame deletions, splice-site, and missense mutations have been found in the syndrome. Haploinsufficiency of PTCH1, which is caused by interstitial deletion of 9q22.3, is also responsible for the syndrome. To date, 19 cases with interstitial deletion of long arm of chromosome 9 involving the region of q22 have been reported. We describe two unrelated patients with some typical features of BCNS associated with deletion of 9q21.33-q31.1 and determined the boundary of the deletion by fluorescence in situ hybridization (FISH) with bacterial artificial chromosome (BAC) clones. The results showed that the size of deletions is between 15.33 and 16.04 Mb in patient 1 and between 18.08 and 18.54 Mb in patient 2. Although the size and breakpoints were different from those of previously reported cases, the clinical features are common to patients with 9q22 deletion associated with BCNS. Delineation of the 9q22 deletions and further consideration of the genes responsible for the characteristic manifestations may provide insight into this newly recognized deletion syndrome.

Orofacial manifestations of Robinow's syndrome: a case report in a pediatric patient

Robinow's syndrome (Online Mendelian Inheritance in Man [OMIM] 268310), or fetal facies syndrome, is a rare genetic disorder causing autosomal dominant and recessive forms. This syndrome includes a series of anomalies such as short stature, characteristic facial dysmorphism (fetal facies), genital hypoplasia, and mesomelic brachymelia. The purpose of the present case is to describe the orofacial manifestations of the syndrome in a pediatric patient: craniofacial features, triangular mouth and a long upper lip philtrum, ankyloglossia, a shortened tongue devoid of tongue tip, a geographic tongue, arched palate, gingival hyperplasia, dental abnormalities (misaligned and crowded teeth), and delayed tooth eruption.

A girl with deletion 9q22.1-q22.32 including the PTCH and ROR2 genes identified by genome-wide array-CGH

The underlying genetic cause of mental retardation (MR) remains unknown in about half of the cases. Recently, using whole genome array comparative genomic hybridization (array-CGH), submicroscopic genetic imbalances have been detected in up to 20% of patients with an unexplained MR, dysmorphic features, and apparently normal karyotype. Here, we present a 12-year-old girl with features of basal cell nevus syndrome (BCNS), pulmonary valve stenosis, and MR, in whom array-CGH identified a 7.7 Mb deletion on 9q22.1-q22.32. The deleted region includes, among others, the ROR2 and PTCH genes. Haploinsufficiency of PTCH causes the BCNS syndrome and mutations in ROR2 have been found in an autosomal recessive Robinow syndrome and a dominantly inherited brachydactyly type 1B. We speculate that haploinsufficiency of ROR2 may contribute to pulmonary valve stenosis. Because of an age-dependent penetrance, BCNS may be challenging for diagnosis particularly when the features are not part of a typical clinical spectrum of BCNS. Early diagnosis of BCNS is important for preventing the development of associated tumors and better care of the patient. Our data confirm the previous observations that application of the whole genome array-CGH should be considered in selected patients with undiagnosed MR and dysmorphic features.

High-density oligonucleotide array with sub-kilobase resolution reveals breakpoint information of submicroscopic deletions in nevoid basal cell carcinoma syndrome

Small submicroscopic genomic deletions and duplications constitute up to 15% of all mutations underlying human monogenic diseases. In this study, we used newly designed high-resolution oligonucleotide microarrays with a median distance between the probes of 776 bp (average probe interval 2,271 bp) to detect gene deletions in nevoid basal cell carcinoma syndrome (NBCCS) patients. NBCCS, also called Gorlin syndrome, is characterized by developmental defects and tumorigenesis such as medulloblastomas and basal cell carcinomas, caused by mutations of the human patched-1 (PTCH1) gene. Two out of three deletions could not be detected by a conventional chromosomal analysis. A submicroscopic deletion as small as 165 kb was detected affecting only PTCH1, whereas the other two deletions were much larger (5 and 11 Mb). We demonstrated not only the exact number of genes involved in the deletion but also rapidly determined the junction sequences after pinpointing the breakpoint regions in all individuals analyzed. This report of an array-based determination of junction sequences of long deletions circumvented a labor-intensive analysis such as Southern blotting or FISH. Alu-mediated recombination in one case and non-homologous end joining in the other two were probably implicated in the generation of deletions. This method will contribute to the understanding of molecular pathogenesis of gene deletions as well as rapid genetic testing.

PTCH mutations and deletions in patients with typical nevoid basal cell carcinoma syndrome and in patients with a suspected genetic predisposition to basal cell carcinoma: a French study

The patched (PTCH) mutation rate in nevoid basal cell carcinoma syndrome (NBCCS) reported in various studies ranges from 40 to 80%. However, few studies have investigated the role of PTCH in clinical conditions suggesting an inherited predisposition to basal cell carcinoma (BCC), although it has been suggested that PTCH polymorphisms could predispose to multiple BCC (MBCC). In this study, we therefore performed an exhaustive analysis of PTCH (mutations detection and deletion analysis) in 17 patients with the full complement of criteria for NBCCS (14 sporadic and three familial cases), and in 48 patients suspected of having a genetic predisposition to BCC (MBCC and/or age at diagnosis ⩽40 years and/or familial BCC). Eleven new germline alterations of the PTCH gene were characterised in 12 out of 17 patients harbouring the full complement of criteria for the syndrome (70%). These were frameshift mutations in five patients, nonsense mutations in five patients, a small inframe deletion in one patient, and a large germline deletion in another patient. Only one missense mutation (G774R) was found, and this was in a patient affected with MBCC, but without any other NBCCS criterion. We therefore suggest that patients harbouring the full complement of NBCCS criteria should as a priority be screened for PTCH mutations by sequencing, followed by a deletion analysis if no mutation is detected. In other clinical situations that suggest genetic predisposition to BCC, germline mutations of PTCH are not common.

Interstitial 9q22.3 microdeletion: clinical and molecular characterisation of a newly recognised overgrowth syndrome

In the course of a systematic whole genome screening of patients with unexplained overgrowth syndrome by microarray-based comparative genomic hybridisation (array-CGH), we have identified two children with nearly identical 6.5 Mb-long de novo interstitial deletions at 9q22.32-q22.33. The clinical phenotype includes macrocephaly, overgrowth and trigonocephaly. In addition, both children present with psychomotor delay, hyperactivity and distinctive facial features. Further analysis with a high-resolution custom microarray covering the whole breakpoint intervals with fosmids mapped the deletion breakpoints within 100-kb intervals: although the deletion boundaries are different for the two patients, nearly the same genes are deleted in both cases. We suggest therefore that microdeletion of 9q22.32-q22.33 is a novel cause of overgrowth and mental retardation. Its association with distinctive facial features should help in recognising this novel phenotype.

Aberrant expression of PTCH (patched gene) and Smo (smoothened gene) in human pancreatic cancerous tissues and its association with hyperglycemia

OBJECTIVES

To investigate the prevalence of PTCH (patched gene) and Smo (smoothened gene) expression in human pancreatic cancerous tissues and its association with clinical characteristics.

METHODS

A rabbit polyclonal antibody against PTCH was prepared through the immunization of prokaryotic recombinant PTCH1170-1433 protein. The PTCH and Smo expression in 39 resected pancreas specimens from 28 patients with pancreatic cancer, 6 with chronic pancreatitis (as control), and 5 with pancreatic pseudocyst (as control) were detected by reverse transcriptase polymerase chain reaction and immunohistochemistry. The relationships between their expressions and pathological characteristics such as tumor sizes, degree of differentiation, nodal status, distant metastasis, and the blood sugar level were analyzed.

RESULTS

The prevalence of PTCH and Smo expressions in cancerous tissues were 71.4% (20/28) and 53.6% (15/28), respectively, whereas no expression in the nontumor pancreas tissues was found. Both PTCH and Smo expressions correlated with the low levels of tumor tissue differentiation (P < 0.05) and PTCH and Smo expressions in islet cells of cancerous tissues associated with hyperglycemia.

CONCLUSIONS

Because aberrant expressions of PTCH and Smo were common in human pancreatic carcinoma tissues and were associated with the low-level differentiation of tumor tissue and hyperglycemia, this indicated that these molecules played a fundamental role in pancreas tumorigenesis and were regarded as new targets for diagnosis and treatment of human pancreatic cancer.

Macrocephaly and the control of brain growth in autistic disorders

Autism is a childhood-onset neuropsychiatric disorder characterized by marked impairments in social interactions and communication, with restricted stereotypic and repetitive patterns of behavior, interests, and activities. Genetic epidemiology studies indicate that a strong genetic component exists to this disease, but these same studies also implicate significant environmental influence. The disorder also displays symptomatologic heterogeneity, with broad individual differences and severity on a graded continuum. In the search for phenotypes to resolve heterogeneity and better grasp autism's underlying biology, investigators have noted a statistical overrepresentation of macrocephaly, an indicator of enlarged brain volume. This feature is one of the most widely replicated biological findings in autism. What then does brain enlargement signify? One hypothesis invoked for the origin of macrocephaly is a reduction in neuronal pruning and consolidation of synapses during development resulting in an overabundance of neurites. An increase in generation of cells is an additional mechanism for macrocephaly, though it is less frequently discussed in the literature. Here, we review neurodevelopmental mechanisms regulating brain growth and highlight one underconsidered potential causal mechanism for autism and macrocephaly--an increase in neurogenesis and/or gliogenesis. We review factors known to control these processes with an emphasis on nuclear receptor activation as one signaling control that may be abnormal and contribute to increased brain volume in autistic disorders.

Delineation of an interstitial 9q22 deletion in basal cell nevus syndrome

Basal cell nevus syndrome (Gorlin syndrome) is an autosomal dominant disorder characterized by the presence of multiple basal cell carcinomas (BCC), odontogenic keratocysts, palmoplantar pits, and calcification in the falx cerebri caused by mutational inactivation of the PTCH gene. In few cases, the syndrome is due to a microdeletion at 9q22. Using high-resolution chromosome analysis we have identified a patient with the karyotype, 46,XY,del(9)(q21.3q31) de novo. He had typical clinical features consistent with basal cell nevus syndrome, but also additional features likely to be caused by loss of additional chromosomal material in this region. The deletion breakpoints were characterized with fluorescence in situ hybridization (FISH) analysis using BAC clones. The 15 Mb long deletion includes 87 RefSeq genes including PTCH. Hemizygosity of one or more genes might contribute to the additional symptoms observed in this patient.

[Calcification of the falx cerebri. A pathognomonic symptom of Gorlin-Goltz syndrome]

BACKGROUND

Gorlin-Goltz syndrome is an autosomal dominant disorder with variable penetration characterized primarily by keratocysts of the jaws, multiple basal cell carcinomas, skeletal abnormalities and intracranial calcifications.

METHOD

In this study, 4787 radiographs with occipitomental x-rays from the hospital archives for oral and maxillofacial surgery of the Christian Albrechts University Kiel were examined for calcifications in the area of the falx cerebri.

RESULTS

Four characteristic alterations in the falx cerebri could be assigned to four groups of structures. Those in group 4 could be found only within Gorlin-Goltz syndrome patients, and differed significantly in form and extent from the remaining three groups.

CONCLUSION

The plurilamellar appearance of this group could be rated as a pathognomonic symptom of the Gorlin-Goltz syndrome.

Microarray based comparative genomic hybridisation (array-CGH) detects submicroscopic chromosomal deletions and duplications in patients with learning disability/mental retardation and dysmorphic features

The underlying causes of learning disability and dysmorphic features in many patients remain unidentified despite extensive investigation. Routine karyotype analysis is not sensitive enough to detect subtle chromosome rearrangements (less than 5 Mb). The presence of subtle DNA copy number changes was investigated by array-CGH in 50 patients with learning disability and dysmorphism, employing a DNA microarray constructed from large insert clones spaced at approximately 1 Mb intervals across the genome. Twelve copy number abnormalities were identified in 12 patients (24% of the total): seven deletions (six apparently de novo and one inherited from a phenotypically normal parent) and five duplications (one de novo and four inherited from phenotypically normal parents). Altered segments ranged in size from those involving a single clone to regions as large as 14 Mb. No recurrent deletion or duplication was identified within this cohort of patients. On the basis of these results, we anticipate that array-CGH will become a routine method of genome-wide screening for imbalanced rearrangements in children with learning disability.