Application of Clinical Genetics最新文献

Erythropoietic protoporphyria (EPP) and the phenotypically similar disease X-linked protoporphyria (XLPP) are inherited cutaneous porphyrias characterized clinically by acute non-blistering photosensitivity, intolerance to sunlight, and significantly reduced quality of life. They are due to marked overproduction of protoporphyrin (PP) chiefly by erythroblasts and reticulocytes. In EPP, the underlying genetic defect is in the ferrochelatase gene, which encodes the final enzyme in the heme synthetic pathway. In XLPP, the genetic defect is a gain-of-function mutation, usually a four-base deletion, in the gene that encodes the enzyme 5-aminolevulinic acid synthase-2, the first and rate-controlling enzyme of heme synthesis in developing red blood cells. The excess PP causes acute and painful photosensitivity, being activated by light in the long ultraviolet to blue spectrum (380-420 nm, the Soret band). Although several treatments have been proposed, presently no very effective treatment exists for EPP or XLPP. Afamelanotide (Scenesse^®) is a first-in-class synthetic analog of α-melanocyte stimulating hormone. Afamelanotide mimics the naturally occurring hormone to increase skin pigmentation by increasing melanin production in melanocytes, resulting in increased sunlight tolerance in those with EPP/XLPP. Afamelanotide is currently approved for use in the European Union and Switzerland, and it is under review in the United States by the Food and Drug Administration for use in patients with EPP/XLPP. This paper provides a review of the clinical characteristics and current therapies for EPP/XLPP. We discuss the pharmacology, clinical efficacy, safety, and tolerability of afamelanotide and summarize the results of several key Phase II and III clinical trials. These data indicate that afamelanotide is a promising therapy for those with these debilitating diseases.

Errors in the binary status of some response traits are frequent in human, animal, and plant applications. These error rates tend to differ between cases and controls because diagnostic and screening tests have different sensitivity and specificity. This increases the inaccuracies of classifying individuals into correct groups, giving rise to both false-positive and false-negative cases. The analysis of these noisy binary responses due to misclassification will undoubtedly reduce the statistical power of genome-wide association studies (GWAS). A threshold model that accommodates varying diagnostic errors between cases and controls was investigated. A simulation study was carried out where several binary data sets (case-control) were generated with varying effects for the most influential single nucleotide polymorphisms (SNPs) and different diagnostic error rate for cases and controls. Each simulated data set consisted of 2000 individuals. Ignoring misclassification resulted in biased estimates of true influential SNP effects and inflated estimates for true noninfluential markers. A substantial reduction in bias and increase in accuracy ranging from 12% to 32% was observed when the misclassification procedure was invoked. In fact, the majority of influential SNPs that were not identified using the noisy data were captured using the proposed method. Additionally, truly misclassified binary records were identified with high probability using the proposed method. The superiority of the proposed method was maintained across different simulation parameters (misclassification rates and odds ratios) attesting to its robustness.

Lysosomal acid lipase deficiency (LAL-D) is a rare disorder of cholesterol metabolism with an autosomal recessive mode of inheritance. The absence or deficiency of the LAL enzyme gives rise to pathological accumulation of cholesterol esters in various tissues. A severe LAL-D phenotype manifesting in infancy is associated with adrenal calcification and liver and gastrointestinal involvement with characteristic early mortality. LAL-D presenting in childhood and adulthood is associated with hepatomegaly, liver fibrosis, cirrhosis, and premature atherosclerosis. There are currently no curative pharmacological treatments for this life-threatening condition. Supportive management with lipid-modifying agents does not ameliorate disease progression. Hematopoietic stem cell transplantation as a curative measure in infantile disease has mixed success and is associated with inherent risks and complications. Sebelipase alfa (Kanuma) is a recombinant human LAL protein and the first enzyme replacement therapy for the treatment of LAL-D. Clinical trials have been undertaken in infants with rapidly progressive LAL-D and in children and adults with later-onset LAL-D. Initial data have shown significant survival benefits in the infant group and improvements in biochemical parameters in the latter. Sebelipase alfa has received marketing authorization in the United States and Europe as long-term therapy for all affected individuals. The availability of enzyme replacement therapy for this rare and progressive disorder warrants greater recognition and awareness by physicians.

Idiopathic pulmonary fibrosis (IPF) is a group of common and lethal forms of idiopathic interstitial pulmonary disease. IPF is characterized by a progressive decline in lung function with a median survival of 2-3 years after diagnosis. Although the pathogenesis of the disease remains unknown, genetic predisposition could play a causal role in IPF. A set of genes have been identified as candidate genes of IPF in the past 20 years. However, the recent technological advances that allow for the analysis of millions of polymorphisms in different subjects have deepened the understanding of the genetic complexity of IPF susceptibility. Genome-wide association studies and whole-genome sequencing continue to reveal the genetic loci associated with IPF risk. In this review, we describe candidate genes on the basis of their functions and aim to gain a better understanding of the genetic basis of IPF. The discovered candidate genes may help to clarify pivotal aspects in the diagnosis, prognosis, and therapies of IPF.

Introduction: Crusted or Norwegian scabies is an infectious skin dermatopathology usually associated with an underlying immunodeficiency condition. It is caused when the mite Sarcoptes scabiei infects the skin, and the immune system is unable to control its spread, leading to a massive hyperinfestation with a simultaneous inflammatory and hyperkeratotic reaction. This is the first report of a novel 1p36 duplication associated with a recurrent infection of crusted scabies.

Case report: We describe a 34-year-old patient with a cutaneous immunodeficiency characterized by recurrent crusted scabies infestation, diffuse tinea, and recurrent staphylococcal cellulitis, who we suspected had an undiagnosed syndrome. The patient also suffered from mental retardation, renal failure, and premature senescence. A cytogenetic fluorescence in situ hybridization analysis revealed a 9.34 Mb duplication within the short (p) arm of chromosome 1, precisely from 1p36.11 to 1p36.21, with an adjacent 193 kb copy gain entirely within 1p36.11. In addition, chromosome 4 had a 906 kb gain in 4p16.1 and chromosome 9 had a 81 kb copy gain in 9p24.3. Over 100 genes localized within these duplicated regions. Gene expression array revealed 82 genes whose expression changed >1.5-fold compared to a healthy age-matched skin control, but among them only the lipolytic enzyme arylacetamide deacetylase-like 3 was found within the duplicated 1p36 region of chromosome 1.

Discussion: Although genetic duplications in the 1p36 region have been previously described, our report describes a novel duplicative variant within the 1p36 region. The patient did not have a past history of immunosuppression but was afflicted by a recurrent case of crusted scabies, raising the possibility that the recurrent infection was associated with the 1p36 genetic duplication.

Conclusion: To our knowledge, the specific duplicated sequence between 1p36.11 and p36.21 found in our patient has never been previously reported. We reviewed and compared the clinical, genotyping, and gene microarray results of our patient in order to characterize this novel 1p36 duplication syndrome, which might have contributed to the recurrent scabies infection in this patient.