Faculty Bibliography

Brooke-Spiegler syndrome (BSS, familial cylindromatosis or turban tumor syndrome) is an inherited disease characterized by neoplasms of the skin appendages such as cylindroma, trichoepithelioma, and spiradenoma. The disease has been mapped to 16q12-13, and mutations in the CYLD gene have been identified in families with this disorder. Of interest, multiple familial trichoepithelioma (MFT) has been described as a distinct disorder characterized by the familial occurrence of trichoepitheliomas. MFT has been mapped to 9p21; however, to date a candidate gene has not been identified. In this report, we describe a four-generation family with BSS presenting predominantly with trichoepitheliomas (resembling MFT phenotype). We identified a novel missense mutation in the CYLD gene, designated E474G, in the affected individuals of this family. Our findings exemplify clinical heterogeneity within BSS and extend the body of evidence that mutations in CYLD are implicated in this disease. Although not conclusive, these findings suggest that BSS and MFT may represent a single entity.

Brooke-Spiegler syndrome is an autosomal dominantly inherited disease with predisposition to neoplasms of the skin appendages. The disease has been mapped to 16q, and mutations in the CYLD gene have been identified in families with this disorder. We describe an individual with BSS exhibiting clinical heterogeneity in which a heterozygous frameshift mutation in CYLD, 2172delA, has been identified. These findings extend the body of evidence that mutations in CYLD are involved in Brooke-Spiegler syndrome and provide additional information for phenotype-genotype correlation.

Mal de Meleda is a rare, autosomal recessive form of palmoplantar keratoderma. The disease has been mapped to chromosome 8 qter, and recently mutations in the ARS (component B) gene have been identified in families with this disorder. We describe a small family of Turkish origin with Mal de Meleda and identified a novel homozygous mutation, L98P, in ARS (component B). These findings extend the body of evidence implicating mutations in the ARS (component B) gene in Mal de Meleda.

Pachyonychia congenita is characterized by hypertrophic nail dystrophy and associated ectodermal features. PC-1 subtype is associated with mutations in keratins 6a or 16, whereas PC-2 subtype is linked to mutations in keratins 6b or 17. The correlation between the mutated gene and the type of PC has generally been consistent. In this report, we describe a case with overlapping clinical features of PC-1 and PC-2 in which a mutation in K6a was identified.

The BRCA1 tumor suppressor has been implicated in many cellular pathways, but the mechanisms by which it suppresses tumor formation are not fully understood. In vivo BRCA1 forms a heterodimeric complex with the related BARD1 protein, and its enzymatic activity as a ubiquitin ligase is largely dependent upon its interaction with BARD1. To explore the genetic relationship between BRCA1 and BARD1, we have examined the phenotype of Bard1-null mice. These mice become developmentally retarded and die between embryonic day 7.5 (E7.5) and E8.5. Embryonic lethality results from a severe impairment of cell proliferation that is not accompanied by increased apoptosis. In the absence of p53, the developmental defects associated with Bard1 deficiency are partly ameliorated, and the lethality of Bard1; p53-nullizygous mice is delayed until E9.5. This result, together with the increased chromosomal aneuploidy of Bard1 mutant cells, indicates a role for Bard1 in maintaining genomic stability. The striking similarities between the phenotypes of Bard1-null, Brca1-null, and double Bard1; Brca1-null mice provide strong genetic evidence that the developmental functions of Brca1 and Bard1 are mediated by the Brca1/Bard1 heterodimer.

Mal de Meleda is a rare form of palmoplantar keratoderma, and recently mutations in the ARS (component) B gene have been identified in families with this disease. We identified a recurrent nonsense mutation, R96X, in four families of Turkish descent. In this report, we demonstrate that these families share a common ancestral haplotype at the mal de Meleda locus, suggesting a founder effect.

Mal de Meleda is a rare, autosomal recessive form of palmoplantar keratoderma. The disease has been mapped to chromosome 8qter, and in a recent study mutations in the ARS gene have been identified in families with this disorder. Here, we report two unrelated families with mal de Meleda, in which two different homozygous mutations in the ARS gene were identified. These findings support the notion that mutations in the ARS gene are pathogenic in mal de Meleda.

Acute infectious purpura fulminans is a rapidly progressive syndrome of hemorrhagic skin necrosis associated with acute infection and disseminated intravascular coagulation. We report 5 cases of purpura fulminans and briefly review the literature. All cases were associated with encapsulated organisms (Streptococcus pneumoniae or Group A streptococcus), and 4 of the 5 patients had asplenism or functional hyposplenism.

Cowden syndrome (CS) and Bannayan-Zonana syndrome (BZS) are two inherited hamartoma syndromes characterized by distinct phenotypic features. Mutations in the PTEN gene have been identified in patients with CS and BZS, suggesting the presence of a common genetic basis. We describe a single kindred with individuals manifesting both CS and BZS phenotypes (CS/BZS overlap family) in which we have identified a novel mutation in PTEN by DNA sequencing. We have confirmed these results by means of restriction enzyme analysis. The presence of individuals with CS and BZS within the same family, and moreover the identification of identical PTEN gene mutations in these individuals, suggest that these two syndromes represent different phenotypic expressions of one disease. Furthermore, these findings imply that, like patients with CS, individuals with BZS should be monitored for the onset of malignancy.

Cowden syndrome (CS) and Bannayan Zonana syndrome (BZS) are two autosomal dominantly inherited conditions characterized by hamartomas. Mutations in PTEN, a tumor suppressor gene located on chromosome 10q23, have been identified in patients with phenotypic findings of both CS and BZS. These mutations are found throughout the entire gene, with exon 5 being the most common site, and include point mutations, insertions and deletions. To date, 11 point mutations at the splice junctions of the PTEN gene have been reported, however, data on the alterations in the transcripts have been lacking. In this study, we have identified three novel splice site mutations in PTEN, in two families with CS and in one individual with BZS. One mutation affected the splice-acceptor site, which resulted in out-of-frame skipping of an entire exon. By contrast, the other two mutations affected the splice-donor sites, and both showed inclusion of partial intronic sequences in the transcript due to activation of cryptic splice sites. These data demonstrate mRNA alterations as a consequence of splice site mutations in the PTEN gene.