Hereditary spastic paraparesis presenting as cerebral palsy due to ADD3 variant with mechanistic insight provided by a Drosophila γ-adducin model.

Cerebral palsy (CP) causes neurological disability in early childhood. Hypoxic-ischaemic injury plays a major role in its aetiology, nevertheless, genetic and epigenetic factors may contribute to the clinical presentation. Mutations in ADD3 (encoding γ-adducin) gene have been described in a monogenic form of spastic quadriplegic cerebral palsy (OMIM 601568). We studied a 16-year-old male with spastic diplegia. Several investigations including neurometabolic testing, brain and spine magnetic resonance imaging (MRI) and CGH-Array were normal. Further, clinical genetics assessment and whole exome sequencing (WES) gave the diagnosis. We generated an animal model using Drosophila to study the effects of γ-adducin loss and gain of function. WES revealed a biallelic variant in the ADD3 gene, NM_016824.5(ADD3): c.1100G > A, p.(Gly367Asp). Mutations in this gene have been described as an ultra-rare autosomal recessive, which is a known form of inherited cerebral palsy. Molecular modelling suggests that this mutation leads to a loss of structural integrity of γ-adducin and is therefore expected to result in a decreased level of functional protein. Pan-neuronal over-expression or knock-down of the Drosophila ortholog of ADD3 called hts caused a reduction of life span and impaired locomotion thereby phenocopying aspects of the human disease. Our animal experiments present a starting point to understand the biological processes underpinning the clinical phenotype and pathogenic mechanisms, to gain insights into potential future methods for treating or preventing ADD3 related spastic quadriplegic cerebral palsy.

Drosophila Histone Demethylase KDM4A Has Enzymatic and Non-enzymatic Roles in Controlling Heterochromatin Integrity.

Eukaryotic genomes are broadly divided between gene-rich euchromatin and the highly repetitive heterochromatin domain, which is enriched for proteins critical for genome stability and transcriptional silencing. This study shows that Drosophila KDM4A (dKDM4A), previously characterized as a euchromatic histone H3 K36 demethylase and transcriptional regulator, predominantly localizes to heterochromatin and regulates heterochromatin position-effect variegation (PEV), organization of repetitive DNAs, and DNA repair. We demonstrate that dKDM4A demethylase activity is dispensable for PEV. In contrast, dKDM4A enzymatic activity is required to relocate heterochromatic double-strand breaks outside the domain, as well as for organismal survival when DNA repair is compromised. Finally, DNA damage triggers dKDM4A-dependent changes in the levels of H3K56me3, suggesting that dKDM4A demethylates this heterochromatic mark to facilitate repair. We conclude that dKDM4A, in addition to its previously characterized role in euchromatin, utilizes both enzymatic and structural mechanisms to regulate heterochromatin organization and functions.

Two neutrophilic dermatoses captured simultaneously on histology.

A number of neutrophilic dermatoses are associated with malignancies and their treatment. These rarely occur together in the same patient. A Caucasian 72-year-old male was treated for acute myeloid leukemia (AML) with chemotherapy including daunorubicin and cytarabine. Within 48 hours of commencing treatment, he developed pyrexia and, two days later, disseminated non-tender pink plaques on the limbs and trunk. A skin biopsy showed a dermal interstitial infiltrate of lymphocytes, histiocytoid cells and predominantly neutrophils. This extended into the subcutis, where a neutrophilic lobular panniculitis was seen. These findings are consistent with Sweet's syndrome. In addition, a neutrophilic and lymphocytic infiltrate was also present around eccrine coils and lower ducts. The eccrine epithelium showed squamous metaplasia with dyskeratosis and sloughing into the lumen. These latter findings are consistent with neutrophilic eccrine hidradenitis (NEH). These two histologically distinct entities form part of the neutrophilic dermatoses that have been described in oncology patients with reports of concurrent or sequential occurrence of various neutrophilic dermatoses in the same patient. Ours, however, is only the second reported case of simultaneously captured Sweet's and NEH in the setting of AML. The most likely explanation is that of an epiphenomenon, whereby the neutrophilic infiltrate extended around the sweat glands in the context of the neutrophilic dermatosis.

Harlequin ichthyosis: a review of clinical and molecular findings in 45 cases.

OBJECTIVE: To assess the clinical outcomes of 45 cases of harlequin ichthyosis and review the underlying ABCA12 gene mutations in these patients. DESIGN: Multicenter, retrospective, questionnaire-based survey. SETTING: Dermatology research institute. PARTICIPANTS: Patients with harlequin ichthyosis for whom we had performed ABCA12 mutation analysis. MAIN OUTCOME MEASURES: Referring physicians were asked to complete a questionnaire using the patients' notes, detailing the clinical outcome of the affected child. In each case, the causative ABCA12 mutation was identified using standard polymerase chain reaction and sequencing techniques. RESULTS: Of the 45 cases, the ages of the survivors ranged from 10 months to 25 years, with an overall survival rate of 56%. Death usually occurred in the first 3 months and was attributed to sepsis and/or respiratory failure in 75% of cases. The early introduction of oral retinoids may improve survival, since 83% of those treated survived, whereas 76% who were not given retinoids died. Recurrent skin infections in infancy affected one-third of patients. Problems maintaining weight affected 44%. Three children developed an inflammatory arthritis, and developmental delay was reported in 32%. Mutation analysis revealed that 52% of survivors had compound heterozygous mutations, whereas all deaths were associated with homozygous mutations. CONCLUSIONS: Harlequin ichthyosis should be regarded as a severe chronic disease that is not invariably fatal. With improved neonatal care and probably the early introduction of oral retinoids, the number of survivors is increasing. Compound heterozygotes appear to have a survival advantage.

Plasticity in patterns of histone modifications and chromosomal proteins in Drosophila heterochromatin.

Eukaryotic genomes are packaged in two basic forms, euchromatin and heterochromatin. We have examined the composition and organization of Drosophila melanogaster heterochromatin in different cell types using ChIP-array analysis of histone modifications and chromosomal proteins. As anticipated, the pericentric heterochromatin and chromosome 4 are on average enriched for the "silencing" marks H3K9me2, H3K9me3, HP1a, and SU(VAR)3-9, and are generally depleted for marks associated with active transcription. The locations of the euchromatin-heterochromatin borders identified by these marks are similar in animal tissues and most cell lines, although the amount of heterochromatin is variable in some cell lines. Combinatorial analysis of chromatin patterns reveals distinct profiles for euchromatin, pericentric heterochromatin, and the 4th chromosome. Both silent and active protein-coding genes in heterochromatin display complex patterns of chromosomal proteins and histone modifications; a majority of the active genes exhibit both "activation" marks (e.g., H3K4me3 and H3K36me3) and "silencing" marks (e.g., H3K9me2 and HP1a). The hallmark of active genes in heterochromatic domains appears to be a loss of H3K9 methylation at the transcription start site. We also observe complex epigenomic profiles of intergenic regions, repeated transposable element (TE) sequences, and genes in the heterochromatic extensions. An unexpectedly large fraction of sequences in the euchromatic chromosome arms exhibits a heterochromatic chromatin signature, which differs in size, position, and impact on gene expression among cell types. We conclude that patterns of heterochromatin/euchromatin packaging show greater complexity and plasticity than anticipated. This comprehensive analysis provides a foundation for future studies of gene activity and chromosomal functions that are influenced by or dependent upon heterochromatin.

Palmar fasciitis and polyarthritis syndrome associated with transitional cell carcinoma of the bladder.

Palmar fasciitis and polyarthritis syndrome is a rare, disabling, paraneoplastic condition of unknown pathogenesis. There is no known effective treatment, although the condition may be halted by control of the cancer. Previously reported cases have mostly been in patients with advanced ovarian malignancies. We present the case of a 69-year-old woman with this condition in association with bladder carcinoma, together with a review of the literature and discussion of possible therapeutic options.

Loss-of-function mutations of an inhibitory upstream ORF in the human hairless transcript cause Marie Unna hereditary hypotrichosis.

Marie Unna hereditary hypotrichosis (MUHH) is an autosomal dominant form of genetic hair loss. In a large Chinese family carrying MUHH, we identified a pathogenic initiation codon mutation in U2HR, an inhibitory upstream ORF in the 5' UTR of the gene encoding the human hairless homolog (HR). U2HR is predicted to encode a 34-amino acid peptide that is highly conserved among mammals. In 18 more families from different ancestral groups, we identified a range of defects in U2HR, including loss of initiation, delayed termination codon and nonsense and missense mutations. Functional analysis showed that these classes of mutations all resulted in increased translation of the main HR physiological ORF. Our results establish the link between MUHH and U2HR, show that fine-tuning of HR protein levels is important in control of hair growth, and identify a potential mechanism for preventing hair loss or promoting hair removal.

Inhaler-induced pigmentary changes in a 14-year-old girl.

We present a 14-year-old girl with self-induced areas of hypo- and hyperpigmenation on her forearm as a result of applying 10 blasts of an asthmatic aerosol inhaler directly to her skin. We emphasize the importance of being aware of potential danger associated with the common metered-dose inhaler when it is misused.

Sequence finishing and mapping of Drosophila melanogaster heterochromatin.

Genome sequences for most metazoans and plants are incomplete because of the presence of repeated DNA in the heterochromatin. The heterochromatic regions of Drosophila melanogaster contain 20 million bases (Mb) of sequence amenable to mapping, sequence assembly, and finishing. We describe the generation of 15 Mb of finished or improved heterochromatic sequence with the use of available clone resources and assembly methods. We also constructed a bacterial artificial chromosome-based physical map that spans 13 Mb of the pericentromeric heterochromatin and a cytogenetic map that positions 11 Mb in specific chromosomal locations. We have approached a complete assembly and mapping of the nonsatellite component of Drosophila heterochromatin. The strategy we describe is also applicable to generating substantially more information about heterochromatin in other species, including humans.

Sun-safety behaviors of skiers and snowboarders on the South Island of New Zealand.

AIMS: To study sun-protective behaviors among skiers and snowboarders on the South Island of New Zealand and to identify associations with personal characteristics or weather conditions. METHODS: Two hundred twenty-six skiers and snowboarders completed an interviewer-administered questionnaire during September and October 2002. Reported behaviors were used to derive a composite sun-protection index, which was used to divide the sample into "protected" and "unprotected" groups. Odds ratios of being unprotected were calculated by logistic regression. RESULTS: Forty-eight percent (95% CI 42-54%) of interviewees recalled being sunburned while skiing or snowboarding in the past. Sixty-eight percent (95% CI 62-74%) were unaware of any educational messages specific to sun protection while skiing or snowboarding. Women were more likely to be protected from the sun (OR 0.47; 95% CI 0.27-0.81). Having a skin type resistant to burning (OR 1.93; 95% CI 0.92-4.06) and reported awareness of education messages (OR 1.66; 95% CI 0.92-2.99) were associated with not using sun protection. CONCLUSIONS: Sunburn is common and sun protection not used by all. Men are less likely to report use of sun-protection measures. There is no evidence from this study that current strategies are effective in promoting skin protection while skiing or snowboarding.

Mutations in ABCA12 underlie the severe congenital skin disease harlequin ichthyosis.

Harlequin ichthyosis (HI) is the most severe and frequently lethal form of recessive congenital ichthyosis. Although defects in lipid transport, protein phosphatase activity, and differentiation have been described, the genetic basis underlying the clinical and cellular phenotypes of HI has yet to be determined. By use of single-nucleotide-polymorphism chip technology and homozygosity mapping, a common region of homozygosity was observed in five patients with HI in the chromosomal region 2q35. Sequencing of the ABCA12 gene, which maps within the minimal region defined by homozygosity mapping, revealed disease-associated mutations, including large intragenic deletions and frameshift deletions in 11 of the 12 screened individuals with HI. Since HI epidermis displays abnormal lamellar granule formation, ABCA12 may play a critical role in the formation of lamellar granules and the discharge of lipids into the intercellular spaces, which would explain the epidermal barrier defect seen in this disorder. This finding paves the way for early prenatal diagnosis. In addition, functional studies of ABCA12 will lead to a better understanding of epidermal differentiation and barrier formation.

Natural history of atopic dermatitis and its relationship to serum total immunoglobulin E in a population-based birth cohort study.

We investigated the natural history of atopic dermatitis (AD) in a population-based birth cohort and assessed whether children at risk of visible eczema at 5 years of age can be identified from total immunoglobulin E (IgE) levels measured at 8, 12 and 18 months. AD data collected included a whole body examination for visible eczema at 49 months (4 years) and 61 months (5 years) of age and parent completed questionnaire data throughout their early lives. Children were divided into four groups based on their natural history of early AD: persistent (AD at 1, 6, 18, 30 and 42 months, n = 34), intermittent early onset (before 18 months of age, n = 495), intermittent late onset (18-42 months of age, n = 273) and unaffected (n = 429). Visible eczema at 5 years of age was present in 12.2% (117/957) (95% confidence interval [CI] 10.1-14.3%) of the children. Levels of total IgE at 8, 12 and 18 months of age were associated with early onset of AD, but not with AD of later onset. For all four natural history groups, the geometric mean total IgE at 12 months was higher in those who subsequently had visible eczema than those who did not. However, the degree of overlap was such that total IgE at 12 months of age was a poor predictor of eczema at age five. A cutoff point of 78 kU/l had the highest positive predictive value for visible eczema at 5 years of age of 28.6%, with a sensitivity of 12% and specificity of 95%.

Genetics of P-element transposition into Drosophila melanogaster centric heterochromatin.

Heterochromatin is a major component of higher eukaryotic genomes, but progress in understanding the molecular structure and composition of heterochromatin has lagged behind the production of relatively complete euchromatic genome sequences. The introduction of single-copy molecular-genetic entry points can greatly facilitate structure and sequence analysis of heterochromatic regions that are rich in repeated DNA. In this study, we report the isolation of 502 new P-element insertions into Drosophila melanogaster centric heterochromatin, generated in nine different genetic screens that relied on mosaic silencing (position-effect variegation, or PEV) of the yellow gene present in the transposon. The highest frequencies of recovery of variegating insertions were observed when centric insertions were used as the source for mobilization. We propose that the increased recovery of variegating insertions from heterochromatic starting sites may result from the physical proximity of different heterochromatic regions in germline nuclei or from the association of mobilizing elements with heterochromatin proteins. High frequencies of variegating insertions were also recovered when a potent suppressor of PEV (an extra Y chromosome) was present in both the mobilization and selection generations, presumably due to the effects of chromatin structure on P-element mobilization, insertion, and phenotypic selection. Finally, fewer variegating insertions were recovered after mobilization in females, in comparison to males, which may reflect differences in heterochromatin structure in the female and male germlines. FISH localization of a subset of the insertions confirmed that 98% of the variegating lines contain heterochromatic insertions and that these schemes produce a broader distribution of insertion sites. The results of these schemes have identified the most efficient methods for generating centric heterochromatin P insertions. In addition, the large collection of insertions produced by these screens provides molecular-genetic entry points for mapping, sequencing, and functional analysis of Drosophila heterochromatin.

Defective trafficking and cell death is characteristic of skin disease-associated connexin 31 mutations.

Distinct germline mutations in the gene (GJB3) encoding connexin 31 (Cx31) underlie the skin disease erythrokeratoderma variabilis (EKV) or sensorineural hearing loss with/without peripheral neuropathy. Here we describe a number of functional analyses to investigate the effect of these different disease-associated Cx31 mutants on connexon trafficking and intercellular communication. Immunostaining of a biopsy taken from an EKV patient harbouring the R42P mutation revealed sparse epidermal staining of Cx31, and, when present, it had a perinuclear localization. Transfection and microinjection studies in both keratinocytes and fibroblast cell lines also demonstrated that R42P and four other EKV-associated mutant Cx31 proteins displayed defective trafficking to the plasma membrane. The deafness/neuropathy only mutant 66delD had primarily a cytoplasmic localization, but some protein was visualized at the plasma membrane in a few transfected cells. Both 66delD- and R32W-Cx31/EGFP proteins had significantly impaired dye transfer rates compared to wild-type Cx31/EGFP protein. A striking characteristic feature observed with the dominant skin disease Cx31 mutations was a high incidence of cell death. This was not observed with wild-type, R32W 66delD Cx31 proteins. In conclusion, we have identified some key cellular phenotypic differences with respect to disease-associated Cx31 mutations.

Heterochromatic sequences in a Drosophila whole-genome shotgun assembly.

BACKGROUND: Most eukaryotic genomes include a substantial repeat-rich fraction termed heterochromatin, which is concentrated in centric and telomeric regions. The repetitive nature of heterochromatic sequence makes it difficult to assemble and analyze. To better understand the heterochromatic component of the Drosophila melanogaster genome, we characterized and annotated portions of a whole-genome shotgun sequence assembly. RESULTS: WGS3, an improved whole-genome shotgun assembly, includes 20.7 Mb of draft-quality sequence not represented in the Release 3 sequence spanning the euchromatin. We annotated this sequence using the methods employed in the re-annotation of the Release 3 euchromatic sequence. This analysis predicted 297 protein-coding genes and six non-protein-coding genes, including known heterochromatic genes, and regions of similarity to known transposable elements. Bacterial artificial chromosome (BAC)-based fluorescence in situ hybridization analysis was used to correlate the genomic sequence with the cytogenetic map in order to refine the genomic definition of the centric heterochromatin; on the basis of our cytological definition, the annotated Release 3 euchromatic sequence extends into the centric heterochromatin on each chromosome arm. CONCLUSIONS: Whole-genome shotgun assembly produced a reliable draft-quality sequence of a significant part of the Drosophila heterochromatin. Annotation of this sequence defined the intron-exon structures of 30 known protein-coding genes and 267 protein-coding gene models. The cytogenetic mapping suggests that an additional 150 predicted genes are located in heterochromatin at the base of the Release 3 euchromatic sequence. Our analysis suggests strategies for improving the sequence and annotation of the heterochromatic portions of the Drosophila and other complex genomes.