Segmental basaloid follicular hamartomas derive from a post-zygotic SMO p.L412F pathogenic variant and express hair follicle development-related proteins in a pattern that distinguish them from basal cell carcinomas.

Basaloid follicular hamartomas (BFH) are benign small basaloid skin tumors that can present as solitary or multiple lesions. Congenital BFH lesions arranged in a segmental distribution have been described, suggesting they derive from a somatic post-zygotic mutational event. Previously, BFH were described in Happle-Tinschert syndrome, which results from a post-zygotic SMO variant and is characterized by segmental BFH with variable involvement of the teeth, skeleton, and central nervous system. Here, we describe two patients with isolated segmental BFH and no systemic involvement. Paired whole exome sequencing of BFH and normal tissue revealed a pathogenic SMO c.1234 C>T, p.L412F variant restricted to BFH tissue. We characterized the proliferation index and expression of Hedgehog and Wnt/beta-catenin pathway related proteins in segmental BFH compared to sporadic basal cell carcinomas (BCCs) and found that segmental BFH had a lower proliferation index. Although segmental BFH expressed a similar level of Gli-1 compared to BCCs, levels of LEF-1 and SOX-9 expression in BFH were weaker for both and patchier for LEF-1. Our results show that a somatic SMO activating variant causes segmental BFH. Since these patients are prone to developing BCCs, differences in SOX9, LEF1, and Ki-67 expression can help distinguish between these two basaloid lesions.

The scope of health insurance coverage of vitiligo treatments in the United States: Implications for health care outcomes and disparities in children of color.

BACKGROUND: Patients of color are disproportionately impacted by vitiligo. Access to treatment depends greatly on insurance coverage. We, therefore, assessed current vitiligo treatment coverage policies across major United States health insurers to determine current patterns and coverage gaps for vitiligo. METHODS: The study surveyed 15 commercial health care insurers, 50 BlueCross BlueShield (BCBS) plans, Medicare, Medicaid, and Veterans Affairs. Information on treatment coverage for vitiligo, specifically pimecrolimus and tacrolimus, excimer laser therapy, PUVA, and narrow-band (nb)UVB, was collected via an online review of insurance policy documents, confirmed with phone calls to organization representatives, or via a survey of Medicaid providers, and state Medicaid directors. RESULTS: Of 17 organizations with regional or national coverage policies, 12% did not cover topical calcineurin inhibitors, 56% did not cover nbUVB phototherapy, 53% did not cover PUVA phototherapy, and 41% did not cover laser therapy. For BCBS, pimecrolimus and tacrolimus were not covered in 39% and 35% of states, respectively. NbUVB and PUVA therapy were not covered in 20% and 10% of states, respectively. Excimer laser therapy was not covered in 82% of states. Out of 32 states with accessible Medicaid information, 11 did not cover topicals, 5 did not cover nbUVB, 4 did not cover PUVA, and 7 did not cover laser. Two commonly cited reasons for coverage denial were that the treatment indication was considered cosmetic, and certain therapies are not FDA-approved. CONCLUSIONS: There is inequity in the distribution of health among vitiligo patients given current patterns of insurance coverage for treatment, which may have disproportionate impact on patients of color.

PSEUDOXANTHOMA ELASTICUM: DIAGNOSTIC FEATURES, CLASSIFICATION, AND TREATMENT OPTIONS.

INTRODUCTION: Pseudoxanthoma elasticum (PXE), a multisystem orphan disease, clinically affects the skin, the eyes, and the cardiovascular system with considerable morbidity and mortality. The clinical manifestations reflect the underlying pathology consisting of ectopic mineralization of peripheral connective tissues. AREAS COVERED: The diagnostic criteria of PXE include characteristic clinical findings, together with histopathology of accumulation of pleiomorphic elastic structures in the dermis with progressive mineralization, and the presence of mutations in the ABCC6 gene. PXE-like cutaneous changes can also be encountered in other ectopic mineralization disorders, including generalized arterial calcification of infancy (GACI) caused by mutations in the ENPP1 gene. In some cases, overlapping clinical features of PXE/GACI, associated with mutations either in ABCC6 or ENPP1, have been noted. PXE demonstrates considerable inter- and intrafamilial heterogeneity, and consequently, accurate diagnosis is required for appropriate classification with prognostic implications. There is no effective and specific treatment for the systemic manifestations of PXE, but effective therapies to counteract the ocular complications are in current clinical use. EXPERT OPINION: A number of observations in the murine model, the Abcc6-/- mouse, have indicated that the mineral composition of diet, particularly the magnesium content, can influence the severity of the mineralization phenotype. These observations suggest that appropriate dietary interventions, coupled with lifestyle modifications, including smoking cessation, might alleviate the symptoms and improve the quality of life of individuals affected with this, currently intractable, orphan disease.

Novel clinico-molecular insights in pseudoxanthoma elasticum provide an efficient molecular screening method and a comprehensive diagnostic flowchart.

Pseudoxanthoma elasticum (PXE) is a heritable connective tissue disorder characterized by ocular, cutaneous and cardiovascular manifestations. It is caused by mutations in the ABCC6 gene (chr. 16p13.1), encoding a transmembrane transporter protein, the substrate and biological function of which are currently unknown. A comprehensive clinical and molecular study of 38 Belgian PXE probands and 21 relatives (4 affected and 17 carriers) was performed. An extensive clinical evaluation protocol was implemented with serial fundus, skin and cardiovascular evaluation. We report on 14 novel mutations in the ABCC6 gene. We observed extensive variability in severity of both cutaneous and ocular lesions. The type of skin lesion however usually remained identical throughout the evolution of the disorder, while ophthalmological progression was mainly due to functional decline. Peripheral artery disease (53%) and stroke (15%) were significantly more prevalent than in the general population (10-30% and 0.3-0.5% respectively). Interestingly, we also observed a relatively high incidence of subclinical peripheral artery disease (41%) in our carrier population. We highlight the significance of peripheral artery disease and stroke in PXE patients as well as the subclinical manifestations in carriers. Through follow-up data we gained insight into the natural history of PXE. We propose a cost- and time-efficient two-step method of ABCC6 analysis which can be used in different populations. Additionally, we created a diagnostic flowchart and attempted to define the role of molecular analysis of ABCC6 in the work-up of a PXE patient.

Mutation detection in the ABCC6 gene and genotype-phenotype analysis in a large international case series affected by pseudoxanthoma elasticum.

BACKGROUND: Pseudoxanthoma elasticum (PXE), an autosomal recessive disorder with considerable phenotypic variability, mainly affects the eyes, skin and cardiovascular system, characterised by dystrophic mineralization of connective tissues. It is caused by mutations in the ABCC6 (ATP binding cassette family C member 6) gene, which encodes MRP6 (multidrug resistance-associated protein 6). OBJECTIVE: To investigate the mutation spectrum of ABCC6 and possible genotype-phenotype correlations. METHODS: Mutation data were collected on an international case series of 270 patients with PXE (239 probands, 31 affected family members). A denaturing high-performance liquid chromatography-based assay was developed to screen for mutations in all 31 exons, eliminating pseudogene coamplification. In 134 patients with a known phenotype and both mutations identified, genotype-phenotype correlations were assessed. RESULTS: In total, 316 mutant alleles in ABCC6, including 39 novel mutations, were identified in 239 probands. Mutations were found to cluster in exons 24 and 28, corresponding to the second nucleotide-binding fold and the last intracellular domain of the protein. Together with the recurrent R1141X and del23-29 mutations, these mutations accounted for 71.5% of the total individual mutations identified. Genotype-phenotype analysis failed to reveal a significant correlation between the types of mutations identified or their predicted effect on the expression of the protein and the age of onset and severity of the disease. CONCLUSIONS: This study emphasises the principal role of ABCC6 mutations in the pathogenesis of PXE, but the reasons for phenotypic variability remain to be explored.

Advocacy groups as research organizations: the PXE International example.

Advocacy organizations for genetic diseases are increasingly becoming involved in biomedical research, particularly translational research, in order to meet the needs of the individuals that they serve. PXE International, an advocacy organization for the disease pseudoxanthoma elasticum, provides an example of how research can be accelerated by these groups. It has adopted methods that were pioneered by other advocacy organizations, and has integrated these along with new approaches into franchizable elements. The model has been followed for other conditions and has led to the establishment of a common infrastructure to enable advocacy groups to initiate, conduct and accelerate research.

Development of a rapid, reliable genetic test for pseudoxanthoma elasticum.

Mutations in the human ABCC6 gene cause pseudoxanthoma elasticum (PXE), a hereditary disorder that impacts the skin, eyes, and cardiovascular system. Currently, the diagnosis of PXE is based on physical findings and histological examination of a biopsy of affected skin. We have combined two simple, polymerase chain reaction (PCR)-based methods to develop a rapid, reliable genetic assay for the majority of known PXE mutations. After PCR amplification and heteroduplex formation, mutations in exon 24 and exon 28 of the ABCC6 gene were detected with Surveyor nuclease, which cleaves double-stranded DNA at any mismatch site. Mutations originating from deletion of a segment of the ABCC6 gene between exon 23 and exon 29 (ex23_ex29del) were detected by long-range PCR. Size analysis of digestion fragments and long-range PCR products was performed by agarose gel electrophoresis. The methods accurately identified mutations or the absence thereof in 16 affected individuals as confirmed by DNA sequencing. Fifteen patients had one or two point mutations, and two of these individuals carried the ex23_ex29del in their second allele. This mutation detection and mapping strategy provides a simple and reliable genetic assay to assist in diagnosis of PXE, differential diagnosis of PXE-like conditions, and study of PXE genetics.

Testicular microlithiasis in association with pseudoxanthoma elasticum.

PURPOSE: To determine the presence of testicular microlithiasis in male subjects with pseudoxanthoma elasticum (PXE). MATERIALS AND METHODS: Institutional review board approval was obtained for the prospective and retrospective components of this HIPAA-compliant study. Informed consent was obtained from all patients or their parents. Testicular ultrasonography (US) was performed in eight men aged 29-56 years and in one 13-year-old boy, all with confirmed PXE. Two radiologists reviewed the US images by consensus for testicular microlithiasis, testicular masses, and additional testicular abnormalities. Testicular microlithiasis was judged to be classic when at least five microliths were seen on a single US image and to be limited when fewer than five microliths were seen on all obtained US images. Urologic physiologic examinations were performed. A history and/or symptoms of testicular disease also were recorded at the time of examination. Similarly, the testicular US images obtained in two additional men, aged 48 and 59 years, and in another 13-year-old boy were retrospectively reviewed. Histopathologic testicular analysis was performed in one autopsy case. RESULTS: Of the 12 participants, 11 (92%) had classic and one (8%) had limited testicular microlithiasis. None of the 12 participants had evidence of testicular malignancy at US or physical examination. Histopathologic analysis at autopsy revealed intratubular microlithiasis without the calcification of elastic fibers in arterial walls that is characteristic of cutaneous PXE. CONCLUSION: Study findings suggested an association between PXE and testicular microlithiasis. It is possible that the testicular microlithiasis in male subjects who have PXE is related to the underlying PXE abnormality.