Identification of compound heterozygous variants in the noncoding RNU4ATAC gene in a Chinese family with two successive foetuses with severe microcephaly

Background

Whole-exome sequencing (WES) over the last few years has been increasingly employed for clinical diagnosis. However, one caveat with its use is that it inevitably fails to detect disease-causative variants that occur within noncoding RNA genes. Our experience in identifying pathogenic variants in the noncoding RNU4ATAC gene, in a Chinese family where two successive foetuses had been affected by severe microcephaly, is a case in point. These foetuses exhibited remarkably similar phenotypes in terms of their microcephaly and brain abnormalities; however, the paucity of other characteristic phenotypic features had made a precise diagnosis impossible. Given that no external causative factors had been reported/identified during the pregnancies, we sought a genetic cause for the phenotype in the proband, the second affected foetus.

Results

A search for chromosomal abnormalities and pathogenic copy number variants proved negative. WES was also negative. These initial failures prompted us to consider the potential role of RNU4ATAC, a noncoding gene implicated in microcephalic osteodysplastic primordial dwarfism type-1 (MOPD1), a severe autosomal recessive disease characterised by dwarfism, severe microcephaly and neurological abnormalities. Subsequent targeted sequencing of RNU4ATAC resulted in the identification of compound heterozygous variants, one being the most frequently reported MOPD1-causative mutation (51G>A), whereas the other was a novel 29T>A variant. Four distinct lines of evidence (allele frequency in normal populations, evolutionary conservation of the affected nucleotide, occurrence within a known mutational hotspot for MOPD1-causative variants and predicted effect on RNA secondary structure) allowed us to conclude that 29T>A is a new causative variant for MOPD1.

Conclusions

Our findings highlight the limitations of WES in failing to detect variants within noncoding RNA genes and provide support for a role for whole-genome sequencing as a first-tier genetic test in paediatric medicine. Additionally, the identification of a novel RNU4ATAC variant within the mutational hotspot for MOPD1-causative variants further strengthens the critical role of the 5′ stem-loop structure of U4atac in health and disease. Finally, this analysis enabled us to provide prenatal diagnosis and genetic counselling for the mother’s third pregnancy, the first report of its kind in the context of inherited RNU4ATAC variants.

Next-generation sequencing reveals a novel NDP gene mutation in a Chinese family with Norrie disease

PURPOSE

Norrie disease (ND) is a rare X-linked genetic disorder, the main symptoms of which are congenital blindness and white pupils. It has been reported that ND is caused by mutations in the NDP gene. Although many mutations in NDP have been reported, the genetic cause for many patients remains unknown. In this study, the aim is to investigate the genetic defect in a five-generation family with typical symptoms of ND.

METHODS

To identify the causative gene, next-generation sequencing based target capture sequencing was performed. Segregation analysis of the candidate variant was performed in additional family members using Sanger sequencing.

RESULTS

We identified a novel missense variant (c.314C>A) located within the NDP gene. The mutation cosegregated within all affected individuals in the family and was not found in unaffected members. By happenstance, in this family, we also detected a known pathogenic variant of retinitis pigmentosa in a healthy individual.

CONCLUSION

c.314C>A mutation of NDP gene is a novel mutation and broadens the genetic spectrum of ND.

Association of -319 C/T and +49 A/G polymorphisms of CTLA-4 gene in patients with hepatitis C virus infection

INTRODUCTION AND OBJECTIVE

Molecular changes in the CTLA-4 gene can modify the ability to control T lymphocyte proliferation, and promote the persistence or elimination of the hepatitis C virus (HCV). We aimed to investigate the frequency and association of -319 C/T and +49 A/G polymorphism in the CTLA-4 gene in patients infected with HCV.

METHODS

The CTLA-4 gene polymorphisms (-319 C/T in the promoter region, and +49 A/G in exon 1) were analysed by T-ARMS-PCR in 420 individuals, including 205 chronic HCV infected patients and 215 healthy subjects.

RESULTS

We found a positive association of +49G allele with HCV infection (OR 1.48; 95% CI 1.09-2.02; p=.02), and with males (OR 1.80; 95% CI 1.16-2.79; p=.02), both in chronic disease (without cirrhosis). Also, significant differences in +49 A/G genotypes distribution between HCV infected patients and healthy subjects were shown in a dominant genetic model (GG+GA versus AA; OR 1.57; 95% CI 1.05-2.33; p=.04). No significant differences were observed in the -319 C/T polymorphism between HCV infected patients and healthy subjects. Moreover, -319C/+49G haplotype confers susceptibility to HCV genotype 3 infection (OR 10.68; 95% CI 1.17-96.97; p=.04).

CONCLUSIONS

The +49G allele confers susceptibility to HCV infection and with male gender, both in chronic disease. In addition, the -319C/+49G haplotype confers susceptibility to HCV genotype 3 infection. Our results support an important role of the -319 C/T and +49 A/G polymorphisms in HCV infection.

Integrated microarray analysis provided novel insights to the pathogenesis of glaucoma

Glaucoma is characterized as a visual field defect, which is the second most common cause of blindness. The present study performed an integrated analysis of microarray studies of glaucoma derived from Gene Expression Omnibus (GEO). Following the identification of the differentially expressed genes (DEGs) in glaucoma compared with normal control (NC) tissues, the functional annotation, glaucoma-specific protein-protein interaction (PPI) network and transcriptional regulatory network constructions were performed. The acute intraocular pressure (IOP) elevation rat models were established and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed for DEGs expression confirmation. Three datasets were downloaded from GEO. A total of 97 DEGs, 82 upregulated and 15 downregulated were identified in glaucoma compared with NC groups with false discovery rate <0.05. Response to virus and immune response were two significantly enriched GO terms in glaucoma. Valine, leucine and isoleucine degradation was a significantly enriched pathway of DEGs in glaucoma. According to the PPI network, HDAC1, HBN, UBR4 and PDK1 were hub proteins in glaucoma. FOXD3, HNF-4 and AP-1 were the three transcription factors (TFs) derived from top 10 TFs which covered the majority of downstream DEGs in glaucoma. Based on the RT-qPCR results, the expression levels of 3 DEGs, raftlin, lipid raft linker 1 (RFTN1), PBX homeobox 1 (PBX1), HDAC1 were significantly upregulated and the expression of GEM was significantly downregulated in acute IOP elevation rat model at the first and fifth day. These four DEGs had the same expression pattern with our integrated analysis. Therefore, the current study concluded that 6 DEGs, including HEPH, SELENBP1, RFTN1, ID1, HDAC-1 and PBX1 and three TFs, including FOXD3, HNF-4 and AP-1 may be involved with the pathogenesis of glaucoma. The findings of the current study may improve diagnosis and drug design for glaucoma.

Kallmann syndrome and ichthyosis: a case of contiguous gene deletion syndrome

Kallmann syndrome is a genetically heterogeneous form of hypogonadotropic hypogonadism caused by gonadotropin-releasing hormone deficiency and characterized by anosmia or hyposmia due to hypoplasia of the olfactory bulbs; osteoporosis and metabolic syndrome can develop due to longstanding untreated hypogonadism. Kallmann syndrome affects 1 in 10 000 men and 1 in 50 000 women. Defects in 17 genes, including KAL1, have been implicated. Kallmann syndrome can be associated with X-linked ichthyosis, a skin disorder characterized by early onset dark, dry, irregular scales affecting the limb and trunk, caused by a defect of the steroid sulfatase gene (STS). Both KAL1 and STS are located in the Xp22.3 region; therefore, deletions in this region cause a contiguous gene syndrome. We report the case of a 32-year-old man with ichthyosis referred for evaluation of excessive height (2.07 m) and weight (BMI: 29.6 kg/m2), microgenitalia and absence of secondary sex characteristics. We diagnosed Kallmann syndrome with ichthyosis due to a deletion in Xp22.3, a rare phenomenon. Learning points: Kallmann syndrome is a genetically heterogeneous disease characterized by hypogonadotropic hypogonadism with anosmia or hyposmia associated with defects in the production or action of gonadotropin-releasing hormone (GnRH) and hypoplasia of the olfactory bulbs. Several genes have been implicated in Kallmann syndrome, including KAL1, located in the Xp22.3 region, which is responsible for X-linked Kallmann syndrome. KAL1 encodes the protein anosmin-1. X-linked ichthyosis is caused by deficiency of the steroid sulfatase enzyme, encoded by STS, which is also located in the Xp22.3 region. Deletions involving this region can affect both genes and result in contiguous gene syndromes. Phenotype can guide clinicians toward suspicion of a specific genetic mutation. KAL1 mutations are mostly related to microgenitalia, unilateral renal agenesis and synkinesia, although patients need not present all these abnormalities. Longstanding untreated hypogonadism is associated with poor sexual health, osteoporosis and metabolic syndrome with the concomitant risk of developing type 2 diabetes mellitus and obesity. Treatment aims to promote the development of secondary sex characteristics, build and sustain normal bone and muscle mass and restore fertility. Treatment can also help minimize some psychological consequences. Treatments available for patients with congenital GnRH deficiency such as Kallmann syndrome include gonadal steroid hormones, human gonadotropins and GnRH. The choice of therapy depends on the goal or goals.

Identification of the genetic determinants responsible for retinal degeneration in families of Mexican descent

PURPOSE

To investigate the clinical characteristics and genetic basis of inherited retinal degeneration (IRD) in six unrelated pedigrees from Mexico.

METHODS

A complete ophthalmic evaluation including measurement of visual acuities, Goldman kinetic or Humphrey dynamic perimetry, Amsler test, fundus photography, and color vision testing was performed. Family history and blood samples were collected from available family members. DNA from members of two pedigrees was examined for known mutations using the APEX ARRP genotyping microarray and one pedigree using the APEX LCA genotyping microarray. The remaining three pedigrees were analyzed using a custom-designed targeted capture array covering the exons of 233 known retinal degeneration genes. Sequencing was performed on Illumina HiSeq. Reads were mapped against hg19, and variants were annotated using GATK and filtered by exomeSuite. Segregation and ethnicity-matched control sample analyses were performed by dideoxy sequencing.

RESULTS

Six pedigrees with IRD were analyzed. Nine rare or novel, potentially pathogenic variants segregating with the phenotype were detected in IMPDH1, USH2A, RPE65, ABCA4, and FAM161A genes. Among these, six were known mutations while the remaining three changes in USH2A, RPE65, and FAM161A genes have not been previously reported to be associated with IRD. Analysis of 100 ethnicity-matched controls did not detect the presence of these three novel variants indicating, these are rare variants in the Mexican population.

CONCLUSIONS

Screening patients diagnosed with IRD from Mexico identified six known mutations and three rare or novel potentially damaging variants in IMPDH1, USH2A, RPE65, ABCA4, and FAM161A genes that segregated with disease.

Neurological Manifestations of X-Linked Ichthyosis: Case Report and Review of the Literature

A 5-year-old boy presented with mild autism and attention-deficit hyperactivity disorder (ADHD). Chromosomal microarray demonstrated a 1.7 Mb deletion at Xp22.31, which was consistent with X-linked ichthyosis (XLI). Further exam revealed dry, scaly skin on his abdomen and pretibial areas. Patients with mutations involving solely the STS gene or the recurrent ~2 Mb deletion may present with ADHD, whereas those with larger deletions including the NLGN4 gene can present with both ADHD and autism. However, our patient presented with mild autism in addition to ADHD despite having only the recurrent deletion without loss of NLGN4. Such neurological manifestations of XLI warrant attention as practical targets of clinical management.

Cathepsin K Inhibitors for Osteoporosis: Biology, Potential Clinical Utility, and Lessons Learned

Cathepsin K is a cysteine protease member of the cathepsin lysosomal protease family. Although cathepsin K is highly expressed in osteoclasts, lower levels of cathepsin K are also found in a variety of other tissues. Secretion of cathepsin K from the osteoclast into the sealed osteoclast-bone cell interface results in efficient degradation of type I collagen. The absence of cathepsin K activity in humans results in pycnodysostosis, characterized by increased bone mineral density and fractures. Pharmacologic cathepsin K inhibition leads to continuous increases in bone mineral density for ≤5 years of treatment and improves bone strength at the spine and hip. Compared with other antiresorptive agents, cathepsin K inhibition is nearly equally efficacious for reducing biochemical markers of bone resorption but comparatively less active for reducing bone formation markers. Despite multiple efforts to develop cathepsin K inhibitors, potential concerns related to off-target effects of the inhibitors against other cathepsins and cathepsin K inhibition at nonbone sites, including skin and perhaps cardiovascular and cerebrovascular sites, prolonged the regulatory approval process. A large multinational randomized, double-blind phase III study of odanacatib in postmenopausal women with osteoporosis was recently completed. Although that study demonstrated clinically relevant reductions in fractures at multiple sites, odanacatib was ultimately withdrawn from the regulatory approval process after it was found to be associated with an increased risk of cerebrovascular accidents. Nonetheless, the underlying biology and clinical effects of cathepsin K inhibition remain of considerable interest and could guide future therapeutic approaches for osteoporosis.

Pycnodysostosis: Novel Variants in CTSK and Occurrence of Giant Cell Tumor

Pycnodysostosis is an autosomal recessive skeletal dysplasia caused by pathogenic variants in the cathepsin K ( CTSK ) gene. We report seven patients from four unrelated families with this condition in whom we have identified three novel pathogenic variants, c.120 + 1G > T in intron 2, c.399 + 1G > A in intron 4, and c.148T > G (p.W50G) in exon 2, and a known variant, c.568C > T (p.Q190*) in exon 5 of CTSK . We present the clinical, radiographic, and molecular findings of all individuals with molecularly proven pycnodysostosis from the present cohort. We also report the occurrence of giant cell tumor in the skull of a patient with this condition.

Expanding the genetic cause of multiple sulfatase deficiency: A novel SUMF1 variant in a patient displaying a severe late infantile form of the disease

Multiple sulfatase deficiency (MSD) is a rare inherited metabolic disease caused by defective cellular sulfatases. Activity of sulfatases depends on post-translational modification catalyzed by formylglycine-generating enzyme (FGE), encoded by the SUMF1 gene. SUMF1 pathologic variants cause MSD, a syndrome presenting with a complex phenotype. We describe the first Polish patient with MSD caused by a yet undescribed pathologic variant c.337G>A [p.Glu113Lys] (i.e. p.E113K) in heterozygous combination with the known deletion allele c.519+5_519+8del [p.Ala149_Ala173del]. The clinical picture of the patient initially suggested late infantile metachromatic leukodystrophy, with developmental delay followed by regression of visual, hearing and motor abilities as the most apparent clinical symptoms. Transient signs of ichthyosis and minor dysmorphic features guided the laboratory workup towards MSD. Since MSD is a rare disease and there is a variable clinical spectrum, we thoroughly describe the clinical outcome of our patient. The FGE-E113K variant, expressed in cell culture, correctly localized to the endoplasmic reticulum but was retained intracellularly in contrast to the wild type FGE. Analysis of FGE-mediated activation of steroid sulfatase in immortalized MSD cells revealed that FGE-E113K exhibited only approx. 15% of the activity of wild type FGE. Based on the crystal structure we predict that the exchange of glutamate-113 against lysine should induce a strong destabilization of the secondary structure, possibly affecting the folding for correct disulfide bridging between C235-C346 as well as distortion of the active site groove that could affect both the intracellular stability as well as the activity of FGE. Thus, the novel variant of the SUMF1 gene obviously results in functionally impaired FGE protein leading to a severe late infantile type of MSD.

CYP1B1 Cytopathy: Uncommon Phenotype of a Homozygous CYP1B1 Deletion as Internal Corneal Ulcer of Von Hippel

PURPOSE

To report a mutation of CYP1B1 in a newborn with a rare phenotype without the classic features of anterior segment dysgenesis or congenital glaucoma.

METHODS

The newborn presented with diffuse corneal edema and bilaterally elevated intraocular pressure (IOP). Ophthalmological examination, ultrasound, and ultrasound biomicroscopy were performed; congenital infections were ruled out. Genetic analysis was performed. The patient underwent penetrating keratoplasty and goniotomy in a single surgical time. The button was subjected to histopathological examination.

RESULTS

The patient is the first child of young, healthy, consanguineous parents. Ophthalmological examination revealed visual acuity of light perception and increased IOP in both eyes. CYP1B1 gene analysis demonstrated homozygosity for a 1-bp deletion in exon 2 (c.830delT). IOP was normalized, and the corneal button was clear after surgical treatment. Histopathological analysis revealed loss of the Bowman membrane in the central cornea, fibrosis of the stroma, absence of endothelial cells, and loss of Descemet membrane centrally.

CONCLUSIONS

We present an uncommon mutation and clinical description of CYP1B1. This report and further studies could provide us better understanding of the mutational spectrum of CYP1B1.

Chromosome 13q deletion syndrome involving 13q31‑qter: A case report

Partial deletions on the long arm of chromosome 13 lead to a number of different phenotypes depending on the size and position of the deleted region. The present study investigated 2 patients with 13q terminal (13qter) deletion syndrome, which manifested as anal atresia with rectoperineal fistula, complex type congenital heart disease, esophageal hiatus hernia with gastroesophageal reflux, facial anomalies and developmental and mental retardation. Array comparative genomic hybridization identified 2 regions of deletion on chromosome 13q31‑qter; 20.38 Mb in 13q31.3‑qter and 12.99 Mb in 13q33.1‑qter in patients 1 and 2, respectively. Comparisons between the results observed in the present study and those obtained from patients in previous studies indicate that the gene encoding ephrin B2 (EFNB2) located in the 13q33.3‑q34 region, and the gene coding for endothelin receptor type B, in the 13q22.1‑31.3 region, may be suitable candidate genes for the observed urogenital/anorectal anomalies. In addition, the microRNA‑17‑92a‑1 cluster host gene and the glypican 6 gene in the 13q31.3 region, as well as EFNB2 and the collagen type IV a1 chain (COL4A1) and COL4A2 genes in the 13q33.1‑q34 region may together contribute to cardiovascular disease development. It is therefore possible that these genes may be involved in the pathogenesis of complex type congenital heart disease in patients with 13q deletion syndrome.

Gypenosides Inhibits Xanthine Oxidoreductase and Ameliorates Urate Excretion in Hyperuricemic Rats Induced by High Cholesterol and High Fat Food (Lipid Emulsion)

BACKGROUND The aim of this study was to study the effects of gypenosides (GPS) on lowering uric acid (UA) levels in hyperuricemic rats induced by lipid emulsion (LE) and the related mechanisms. GPS are natural saponins extracted from Gynostemma pentaphyllum. MATERIAL AND METHODS Forty-eight male SD rats were randomly divided into six groups: normal, model, two positive controls, and two GPS treated groups (two different doses of GPS). The normal group rats were fed a basic diet, and the other rats were orally pretreated with LE. Urine and blood were collected at regular intervals. Full automatic biochemical analyzer was used to detect the concentration levels of serum UA (SUA), serum creatinine (SCr), BUN, and urine UA (UUA), and urine creatinine (UCr) and fractional excretion of UA (FEUA). ELISA kits were used to detect enzymes activities: xanthine oxidase (XOD), adenosime deaminase (ADA), guanine deaminase (GDA), and xanthine dehydrogenase (XDH). Immunohistochemistry was used to observe kidney changes and protein (URAT1, GLUT9, and OAT1) expression levels. RT-PCR was used to detect the relevant mRNA expression levels. RESULTS Treatment with GPS significantly reduced the SUA, prevented abnormal weight loss caused by LE, and improved kidney pathomorphology. Treatment with GPS also decreased the levels of XOD, ADA, and XDH expression, increased the kidney index and FEUA, downregulated URAT1 and GLUT9 expression and upregulated OAT1 expression in the kidney. CONCLUSIONS GPS may be an effective treatment for hyperuricemia via a decrease in xanthine oxidoreductase through the XOD/XDH system; and via an increase in urate excretion through regulating URAT1, GLUT9, and OAT1 transporters.

Two cases of Legg-Perthes and intellectual disability in Tricho-Rhino-Phalangeal syndrome type 1 associated with novel TRPS1 mutations

Tricho-Rhino-Phalangeal syndrome is a rare autosomal dominant genetic disorder caused by mutations in the TRPS1 gene. This malformation syndrome is characterized by distinctive craniofacial features including sparse scalp hair, bulbous tip of the nose, long flat philtrum, thin upper vermilion border, and protruding ears. Skeletal abnormalities include cone-shaped epiphyses at the phalanges, hip malformations, and short stature. In this report, we describe two patients with the physical manifestations and genotype of TRPS type I but with learning/intellectual disability not typically described as part of the syndrome. The first patient has a novel heterozygous two-base-pair deletion of nucleotides at 3198-3199 (c.3198-3199delAT) in the TRPS1 gene causing a translational frameshift and subsequent alternate stop codon. The second patient has a 3.08 million base-pair interstitial deletion at 8q23.3 (113,735,487-116,818,578), which includes the TRPS1 gene and CSMD3. Our patients have characteristic craniofacial features, Legg-Perthes syndrome, various skeletal abnormalities including cone shaped epiphyses, anxiety (first patient), and intellectual disability, presenting unusual phenotypes that add to the clinical spectrum of the disease.

Neuroimaging Findings in Pediatric Genetic Skeletal Disorders: A Review

Genetic skeletal disorders (GSDs) are a heterogeneous group characterized by an intrinsic abnormality in growth and (re-)modeling of cartilage and bone. A large subgroup of GSDs has additional involvement of other structures/organs beside the skeleton, such as the central nervous system (CNS). CNS abnormalities have an important role in long-term prognosis of children with GSDs and should consequently not be missed. Sensitive and specific identification of CNS lesions while evaluating a child with a GSD requires a detailed knowledge of the possible associated CNS abnormalities. Here, we provide a pattern-recognition approach for neuroimaging findings in GSDs guided by the obvious skeletal manifestations of GSD. In particular, we summarize which CNS findings should be ruled out with each GSD. The diseases (n = 180) are classified based on the skeletal involvement (1. abnormal metaphysis or epiphysis, 2. abnormal size/number of bones, 3. abnormal shape of bones and joints, and 4. abnormal dynamic or structural changes). For each disease, skeletal involvement was defined in accordance with Online Mendelian Inheritance in Man. Morphological CNS involvement has been described based on extensive literature search. Selected examples will be shown based on prevalence of the diseases and significance of the CNS involvement. CNS involvement is common in GSDs. A wide spectrum of morphological abnormalities is associated with GSDs. Early diagnosis of CNS involvement is important in the management of children with GSDs. This pattern-recognition approach aims to assist and guide physicians in the diagnostic work-up of CNS involvement in children with GSDs and their management.

Adult-onset Satoyoshi syndrome in a young male

Satoyoshi syndrome is a rare condition of presumed autoimmune etiology that is characterized by intermittent painful spasms, diarrhea, hair loss, and bone abnormalities. We report the first case of adult onset Satoyoshi syndrome in South America. A 32-year-old Caucasian male presented with sudden involuntary muscle contractions and painful cramps that had started at the age of 21. He also presented with trismus and complete loss of body hair. Electroneuromyography showed abnormal spontaneous activity. Diagnosis of Satoyoshi syndrome was made after extensive investigation; improvement was achieved with corticosteroids and azathioprine. It is a rare disease; few cases have been described worldwide, most of them in Asian children and almost all sporadic. There are several atypical presentations described in the literature. Immunosuppression is the basis of treatment. Professionals dealing with neuromuscular diseases should be aware of this condition and its atypical presentations, given the possible response to immunosuppressive treatment.

Siwu decoction attenuates oxonate-induced hyperuricemia and kidney inflammation in mice

The aim of the study was to investigate the effects of Siwu decoction on hyperuricemia, kidney inflammation, and dysfunction in hyperuricemic mice. Siwu decoction at 363.8, 727.5, and 1 455 mg·kg(-1) was orally administered to potassium oxonate-induced hyperuricemic mice for 7 days. Serum urate, creatinine, and blood urea nitrogen levels and hepatic xanthine oxidase (XOD) activity were measured. The protein levels of hepatic XOD and renal urate transporter 1 (URAT1), glucose transporter 9 (GLUT9), organic anion transporters 1 (OAT1), ATP-binding cassette subfamily G member 2 (ABCG2), organic cation transporter 1 (OCT1), OCT2, organic cation/carnitine transporter 1 (OCTN1), OCNT2, Nod-like receptor family, pyrin domain containing 3 (NLRP3), apoptosis-associated speck-like protein (ASC), Caspase-1, and interleukin-1β (IL-1β) were determined by Western blotting. Renal histopathology change was obtained following hematoxylin-eosin staining. Our results indicated that Siwu decoction significantly reduced serum urate, creatinine and blood urea nitrogen levels and increased fractional excretion of uric acid in hyperuricemic mice. It effectively reduced hepatic XOD activity and protein levels in this animal model. Furthermore, Siwu decoction down-regulated URAT1 and GLUT9 protein levels, and up-regulated the protein levels of OAT1, ABCG2, OCT1, OCT2, OCTN1, and OCTN2 in the kidney of the hyperuricemic mice. Additionally, Siwu decoction remarkably reduced renal protein levels of NLRP3, ASC, Caspase-1, and IL-1β in the hyperuricemic mice. These results suggested that Siwu decoction exhibited anti-hyperuricemic and anti-inflammatory effects by inhibiting hepatic XOD activity, regulating renal organic ion transporter expression, and suppressing renal NLRP3 inflammasome activation, providing the evidence for its use in the treatment of hyperuricemia and associated kidney inflammation.

Characterization of PABPN1 expansion mutations in a large cohort of Mexican patients with oculopharyngeal muscular dystrophy (OPMD)

Oculopharyngeal muscular dystrophy (OPMD) is an autosomal-dominant, adult-onset disorder defined by blepharoptosis, dysphagia, and proximal muscle weakness. OPMD arises from heterozygous expansions of a trinucleotide (GCN) tract situated at the 5' region of the polyadenylate RNA binding protein 1 (PABPN1) gene. The frequency of a particular (GCN) expansion in a given population of patients with OPMD is largely influenced by the occurrence of founder mutations. Analysis of large groups of patients with OPMD from different ethnic origins will help to estimate the relative contribution of each expanded allele to the disease. The purpose of this study was to characterize the type of PABPN1 expanded alleles in a large cohort of OPMD individuals from Mexico. Molecular analysis procedures included genomic DNA extraction from blood leukocytes in each patient followed by PCR amplification of PABPN1 exon 1, and direct nucleotide sequencing of PCR products. A total of 102 patients with OPMD were included in the study. Expanded PABPN1 gene alleles were demonstrated in all patients: 65% (66 out of 102) had a (GCN)15 expansion while the remaining 35% (36 out of 102) exhibited a (GCN)13 expansion. This is one of the largest series of molecularly confirmed patients with OPMD in a non-Caucasian population. Ethnic-specific differences in the prevalence of specific PABPN1 expansions must be considered for genetic screening of patients with OPMD.

Role of steroid sulfatase in steroid homeostasis and characterization of the sulfated steroid pathway: Evidence from steroid sulfatase deficiency

The impact of steroid sulfatase (STS) activity in the circulating levels of both sulfated and unconjugated steroids is only partially known. In addition, the sulfated steroid pathway, a parallel pathway to the one for unconjugated steroids, which uses the same enzymes, has never been characterized in detail before. Patients with steroid sulfatase deficiency (STSD) are unable to enzymatically convert sulfated steroids into their unconjugated forms, and are a good model to elucidate how STS affects steroid biosynthesis and to study the metabolism of sulfated steroids. We quantified unconjugated and sulfated steroids in STSD serum, and compared these results with data obtained from serum of healthy controls. Most sulfated steroids were increased in STSD. However, androstenediol-3-sulfate and epiandrosterone sulfate showed similar levels in both groups, and the concentrations of androsterone sulfate were notably lower. Hydroxylated forms of DHEAS and of pregnenolone sulfate were found to be increased in STSD, suggesting a mechanism to improve the excretion of sulfated steroids. STSD testosterone concentrations were normal, but cholesterol and DHEA were significantly decreased. Additionally, serum bile acids were three-fold higher in STSD. Correlations between concentrations of steroids in each group indicate that 17α-hydroxy-pregnenolone-3-sulfate in men is mainly biosynthesized from the precursor pregnenolone sulfate and androstenediol-3-sulfate from DHEAS. These findings confirm the coexistence of two steroidogenic pathways: one for unconjugated steroids and another one for sulfated steroids. Each pathway is responsible for the synthesis of specific steroids. The equal levels of testosterone, and the reduced level of unconjugated precursors in STSD, support that testosterone is primarily synthesized from sulfated steroids. In consequence, testosterone synthesis in STSD relies on an enzyme with sulfatase activity other than STS. This study reveals that STS is a key player of steroid biosynthesis regulating the availability of circulating cholesterol.

Lesinurad: A significant advancement or just another addition to existing therapies of gout?

Gout is a metabolic disorder that usually presents as recurrent episodes of acute arthritis due to deposition of crystals in joints and cartilages. Despite the availability of several drugs for gout, its management is still less than adequate. There is always a search for newer, safer, and more potent urate-lowering therapies for treating patients inadequately controlled with available drugs. Lesinurad in combination with a xanthine oxidase inhibitor provides an effective mode of therapy in the management of hyperuricemia associated with gout. Lesinurad is a selective uric acid transporter 1 (URAT1) inhibitor. URAT1 is responsible for the majority of uric acid absorption from kidneys to the circulation. Lesinurad was granted marketing approval based on three randomized, double-blind, placebo-controlled; phase III clinical trials. It is devoid of interaction with organic anion transporters (OATs) such as OAT1 and 3, responsible for drug-drug interactions, an undesirable property associated with probenecid. On-going research is more focused on reducing inflammation consequent to deposition of crystals rather than production and excretion of urate. Various targets are being explored, and interleukin-1 beta inhibition seems to be one of the most promising approaches.

Molecular analysis of the CTSK gene in a cohort of 33 Brazilian families with pycnodysostosis from a cluster in a Brazilian Northeast region

Background

Pycnodysostosis is an autosomal recessive skeletal dysplasia, the prevalence of which is estimated to be low (1 per million). Nevertheless, in recent years we have found 27 affected individuals from 22 families in Ceará State, a region of the Brazilian Northeast, giving a local prevalence of 3 per million. This local prevalence associated with a high parental consanguinity, suggesting a possible founder effect, prompted us to perform a molecular investigation of these families to test this hypothesis.

Methods

The CTSK gene was sequenced by the Sanger method in the patients and their parents. In addition to 18 families from Ceará, this study also included 15 families from other Brazilian regions. We also investigated the origin of each family from the birthplace of the parents and/or grandparents.

Results

We have studied 39 patients, including 33 probands and 6 sibs, from 33 families with pycnodysostosis and identified six mutations, five previously described (c.436G>C, c.580G>A, c.721C>T, c.830C>T and c.953G>A) and one novel frameshift (c.83dupT). This frameshift variant seems to have a single origin in Ceará State, since the haplotype study using the polymorphic markers D1S2344, D1S442, D1S498 and D1S2715 suggested a common origin. Most of the mutations were found in homozygosity in the patients from Ceará (83.3 %) while in other states the mutations were found in homozygosity in half of patients. We have also shown that most of the families currently living outside of Ceará have northeastern ancestors, suggesting a dispersion of these mutations from the Brazilian Northeast.

Conclusions

The high frequency of pycnodysostosis in Ceará State is the consequence of the high inbreeding in that region. Several mutations, probably introduced a long time ago in Ceará, must have spread due to consanguineous marriages and internal population migration. However, the novel mutation seems to have a single origin in Ceará, suggestive of a founder effect.

Electronic supplementary material

The online version of this article (doi:10.1186/s40001-016-0228-7) contains supplementary material, which is available to authorized users.

Genetic Predictors of Susceptibility to Dermatophytoses

Countless observational studies conducted over the last century reveal that dermatophytes infect humans of every age, race, gender, and socioeconomic status with strikingly high rates. The curious disparity in dermatophyte infection patterns observed within and between populations has led countless investigators to explore whether genetics underlie a susceptibility to, or confer protection against, dermatophyte infections. This paper examines the data that offer a link between genetics and dermatophytoses and discusses the underlying mechanisms that support these observations.

(WNK)ing at death: With-no-lysine (Wnk) kinases in neuropathies and neuronal survival

Members of With-no-lysine (WNK) family of serine-threonine kinase are key regulators of chloride ion transport in diverse cell types, controlling the activity and the surface expression of cation-chloride (Na(+)/K(+)-Cl(-)) co-transporters. Mutations in WNK1 and WNK4 are linked to a hereditary form of hypertension, and WNKs have been extensively investigated pertaining to their roles in renal epithelial ion homeostasis. However, some members of the WNK family and their splice isoforms are also expressed in the mammalian brain, and have been implicated in aspects of hereditary neuropathy as well as neuronal and glial survival. WNK2, which is exclusively enriched in neurons, is well known as an anti-proliferative tumor suppressor. WNK3, on the other hand, appears to promote cell survival as its inhibition enhances neuronal apoptosis. However, loss of WNK3 has been recently shown to reduce ischemia-associated brain damage. In this review, I surveyed the potentially context-dependent roles of WNKs in neurological disorders and neuronal survival.

Case of multiple sulfatase deficiency and ocular albinism: a diagnostic odyssey

BACKGROUND

Multiple sulfatase deficiency (MSD) is a rare autosomal recessive inborn error of lysosomal metabolism. The clinical phenotypic spectrum encompasses overlapping features of variable severity and is suggestive of individual single sulfatase deficiencies (i.e., metachromatic leukodystrophy, mucopolysaccharidosis, and X-linked ichthyosis).

CASE REPORT

We describe a 3-year-old male with severe hypotonia, developmental regression and progressive neurodegeneration, coarse facial features, nystagmus (from ocular albinism), and dysmyelinating motor sensory neuropathy. Ethics approval was obtained from the Western University Ontario.

RESULTS

Extensive investigative work-up identified deficiencies of multiple sulfatases: heparan sulfate sulfamidase: 6.5 nmoles/mg/protein/17 hour (reference 25.0-75.0), iduronate-2-sulfate sulfatase: 9 nmol/mg/protein/4 hour (reference 31-110), and arylsulfatase A: 3.8 nmoles/hr/mg protein (reference 22-50). The identification of compound heterozygous pathogenic mutations in the SUMF1 gene c.836 C>T (p.A279V) and c.1045C>T (p.R349W) confirmed the diagnosis of MSD.

CONCLUSION

The complex clinical manifestations of MSD and the unrelated coexistence of ocular albinism as in our case can delay diagnosis. Genetic counselling should be provided to all affected families.

The Effect of Multiple Sulfatase Deficiency (MSD) on Dental Development: Can We Use the Teeth as an Early Diagnostic Tool?

BACKGROUND

Multiple sulfatase deficiency (MSD) is a rare autosomal recessive inborn error of metabolism due to reduced catalytic activity of the different sulfatase. Affected individuals show neurologic deterioration with mental retardation, skeletal anomalies, organomegaly, and skin changes as in X-linked ichthyosis. The only organ that was not examined in MSD patients is the dentition.

OBJECTIVES

To evaluate the effect of the metabolic error on dental development in a patient with the intermediate severe late-infantile form of MSD (S155P).

METHODS

Histological and chemical study were performed on three deciduous and five permanent teeth from MSD patient and pair-matched normal patients.

RESULTS

Tooth germ size and enamel thickness were reduced in both deciduous and permanent MSD teeth, and the scalloping feature of the DEJ was missing in MSD teeth causing enamel to break off from the dentin. The mineral components in the enamel and dentin were different.

CONCLUSIONS

The metabolic error insults the teeth in the stage of organogenesis in both the deciduous and permanent dentition. The end result is teeth with very sharp cusp tips, thin hypomineralized enamel, and exposed dentin due to the break off of enamel. These findings are different from all other types of MPS syndromes.Clinically the phenotype of intermediate severe late-infantile form of MSD appeared during the third year of life. In children of parents that are carriers, we can diagnose the disease as early as birth using X-ray radiograph of the anterior upper region or as early as 6-8 months when the first deciduous tooth erupt and consider very early treatment to ameliorate the symptoms.

Steroid Sulfatase Deficiency and Androgen Activation Before and After Puberty

CONTEXT

Steroid sulfatase (STS) cleaves the sulfate moiety off steroid sulfates, including dehydroepiandrosterone (DHEA) sulfate (DHEAS), the inactive sulfate ester of the adrenal androgen precursor DHEA. Deficient DHEA sulfation, the opposite enzymatic reaction to that catalyzed by STS, results in androgen excess by increased conversion of DHEA to active androgens. STS deficiency (STSD) due to deletions or inactivating mutations in the X-linked STS gene manifests with ichthyosis, but androgen synthesis and metabolism in STSD have not been studied in detail yet.

PATIENTS AND METHODS

We carried out a cross-sectional study in 30 males with STSD (age 6-27 y; 13 prepubertal, 5 peripubertal, and 12 postpubertal) and 38 age-, sex-, and Tanner stage-matched healthy controls. Serum and 24-hour urine steroid metabolome analysis was performed by mass spectrometry and genetic analysis of the STS gene by multiplex ligation-dependent probe amplification and Sanger sequencing.

RESULTS

Genetic analysis showed STS mutations in all patients, comprising 27 complete gene deletions, 1 intragenic deletion and 2 missense mutations. STSD patients had apparently normal pubertal development. Serum and 24-hour urinary DHEAS were increased in STSD, whereas serum DHEA and testosterone were decreased. However, total 24-hour urinary androgen excretion was similar to controls, with evidence of increased 5α-reductase activity in STSD. Prepubertal healthy controls showed a marked increase in the serum DHEA to DHEAS ratio that was absent in postpubertal controls and in STSD patients of any pubertal stage.

CONCLUSIONS

In STSD patients, an increased 5α-reductase activity appears to compensate for a reduced rate of androgen generation by enhancing peripheral androgen activation in affected patients. In healthy controls, we discovered a prepubertal surge in the serum DHEA to DHEAS ratio that was absent in STSD, indicative of physiologically up-regulated STS activity before puberty. This may represent a fine tuning mechanism for tissue-specific androgen activation preparing for the major changes in androgen production during puberty.

Tropical Skin Diseases in Children: A Review- Part I

Because of travel and migration patterns, tropical skin diseases are now seen all around the world, not just in tropical or developing countries. Nutrition, housing, and environmental factors play an important role in these infectious diseases, so when they appear out of their normal environments, their classic presentation may vary. Tropical diseases can also present differently in childhood, making their recognition, diagnosis, and management a clinical challenge. Health care providers in developed countries need to be familiar with tropical skin diseases and be able to diagnose them in returning travelers or immigrants in order to optimize care. This article aims to review the epidemiologic, clinical, diagnostic, and therapeutic aspects of some of the most common tropical dermatologic conditions in children.

A Patient With Atypical Multiple Sulfatase Deficiency

BACKGROUND

Multiple sulfatase deficiency is an autosomal recessive lysosomal storage disorder characterized by the absence of several sulfatases and resulting from mutations in the gene encoding the human C (alpha)-formylglycine-generating enzyme. There have been a variety of biochemical and clinical presentations reported in this disorder.

PATIENT DESCRIPTION

We present a 4-year-old girl with clinical findings of microcephaly, spondylolisthesis and neurological regression without ichthyosis, coarse facies, and organomegaly.

RESULTS

The child's magnetic resonance imaging demonstrated confluent white matter abnormalities involving the periventricular and deep cerebral white matter with the U-fibers relatively spared. Biochemical testing showing low arylsulfatase A levels were initially thought to be consistent with a diagnosis of metachromatic leukodystrophy. The diagnosis of multiple sulfatase deficiency was pursued when genetic testing for metachromatic leukodystrophy was negative.

CONCLUSION

This child illustrates the clinical heterogeneity of multiple sulfatase deficiency and that this disorder can occur without the classic clinical features.

The Dutch patients' perspective on oculopharyngeal muscular dystrophy: A questionnaire study on fatigue, pain and impairments

Research on oculopharyngeal muscular dystrophy focuses mainly on genetic and pathophysiological aspects. Clinically, oculopharyngeal muscular dystrophy is often considered as a disease with a relatively mild initial disease course with no or only mild functional disabilities. However the occurrence of fatigue, pain and functional impairments other than dysphagia has never been studied systematically. The aim of this study is therefore to assess the prevalence of fatigue, pain, and functional limitations, and the social participation and psychological well-being of oculopharyngeal muscular dystrophy patients. We performed a questionnaire study on fatigue, pain, functional impairments, social participation and psychological distress in 35 genetically confirmed oculopharyngeal muscular dystrophy patients with an average disease duration of 11.6 years. We showed that 19 (54%) of the patients experienced severe fatigue and also 19 (54%) experienced pain. Limitations in daily life activities and social participation were detected in 33 (94%) of the patients. Many patients reported pelvic girdle weakness and limitations in ambulation. Fatigue severity was related to functional impairments, while pain and disease duration were not. Psychological distress was not different from healthy adults. In conclusion, fatigue and pain are present among approximately half of the patients, and almost all patients are impaired in daily life activities, social participation and ambulation. These data should be taken into account in symptomatic management of oculopharyngeal muscular dystrophy.

Two novel compound heterozygous families with a trimutation in the GJB2 gene causing sensorineural hearing loss

BACKGROUND

Sensorineural hearing loss (SNHL) is a genetically heterogeneous disease. GJB2 gene mutations seem to be the most frequent cause of hereditary hearing impairment in several populations. There is variability in the mutations in the GJB2 gene worldwide; this remarks the influence of ethnic background in SNHL.

OBJECTIVE

To describe the presence of two trimutations in the GJB2 gene in two Mexican families with hereditary SNHL.

MATERIALS AND METHODS

Two unrelated Mexican families with prelingual SNHL were included in the study. Analysis of the GJB2 gene through PCR and DNA direct sequencing analysis was performed in all members of the families and in 100 normal controls.

RESULTS

Affected member of the family 1 showed the trimutation p.S19R/p.R32S/p.E47*, whereas affected members of the family 2 showed the trimutation p.F31I/p.W44*/p.V84M. Parents of both families were heterozygous with normal audition.

CONCLUSION

We found a novel mutation in the GJB2 gene and two trimutations with SNHL not previously reported. This remarks the complexity in the pattern of mutations in the GJB2 gene in SNHL and enriches the spectrum of the type of molecular defects in the GJB2 gene.

Effect of SI-591, a new class of cathepsin K inhibitor with peptidomimetic structure, on bone metabolism in vitro and in vivo

SI-591[N-[1-[[[(1S)-3-[[(3S)-hexahydro-2-oxo-1H-azepin-3-yl]amino]-1-(1-methylethyl)-2,3-dioxopropyl]amino]carbonyl]cyclohexyl]-2-furancarboxamide] is an orally bioavailable compound that was synthesized as one of several unique peptidomimetic compounds without a basic group. This compound was found to have the ability to inhibit cathepsin K, a lysosomal cysteine protease. Cathepsin K is known to be expressed in osteoclasts and involved in bone loss processes. In this study, SI-591 was shown to inhibit the activity of various purified cathepsin molecules at nanomolar concentrations but had high selectivity for cathepsin K over other subtypes including B and L. SI-591 also decreased the level of CTX-I, a bone resorption marker, which was released from osteoclasts in vitro in a dose-dependent manner. The mobilization of calcium from the bones to the blood stream is known to increase in rats fed with a low calcium diet; SI-591 inhibited this increase in serum calcium level at an oral dose of 3mg/kg. Furthermore, SI-591 significantly decreased the level of CTX-I and DPD, bone resorption markers, at oral doses of 10mg/kg or less in ovariectomized rats, while it did not affect the level of BGP, a bone formation marker. In addition, SI-591 prevented bone mineral density loss in the lumber vertebrae and femurs in ovariectomized rats. These results suggest that SI-591 inhibits bone resorption without affecting osteoblast maturation. Therefore, SI-591, a novel cathepsin K inhibitor, could be a promising agent for the treatment of postmenopausal osteoporosis.

The role of cathepsin K in oral and maxillofacial disorders

Cathepsin K (CTSK) was thought to be a collagenase, specifically expressed by osteoclasts, and played an important role in bone resorption. However, more and more research found that CTSK was expressed in more extensive cells, tissues, and organs. It may not only participate in regulating human physiological activity, but also be closely related to a variety of disease. In this review, we highlight the relationship between CTSK and oral and maxillofacial disorders on the following three aspects: oral and maxillofacial abnormities in patients with pycnodysostosis caused by CTSK mutations, oral and maxillofacial abnormities in Ctsk(-/-) mice, and the role of CTSK in oral and maxillofacial diseases, including periodontitis, peri-implantitis, tooth movement, oral and maxillofacial tumor, root resorption, and periapical disease.

[Mucopolysaccharidosis: clinical features, diagnosis and management]

The mucopolysaccharidoses (MPS) are a group of rare (orphan) diseases, characterised by a deficiency of enzymes involved in the metabolism of glycosaminoglycans (GAGs) at lysosomal level. When there is a deficiency of a particular enzyme there is an accumulation of GAGs in the cells resulting in progressive cellular damage, which can affect multiple organ systems and lead to organ failure. Diagnosis is based on knowledge of the clinical manifestations, performing biochemical analyses to identify the type of GAG that is accumulating, and confirm the type of disorder with the corresponding enzymatic determination. Their identification is essential to initiate early treatment, taking into account that multidisciplinary management and enzyme replacement therapy is available for MPS I (Hurler syndrome), MPS II (Hunter syndrome), MPS IV (Morquio syndrome), and MPS VI (Maroteaux-Lamy syndrome. In this review, an analysis is made of each of these syndromes, as well as their diagnosis and treatment.

Expanding the phenotype of feingold syndrome-2

Feingold syndrome-2 has been recently shown to be caused by germline heterozygous deletions of MIR17HG with 10 reported patients to date. Manifestations common to both Feingold syndrome-1 and Feingold syndrome-2 include microcephaly, short stature, and brachymesophalangy; but those with Feingold syndrome-2 lack gastrointestinal atresias. Here we describe a 14-year-old male patient who presented to our Cardiovascular Genetics Clinic with a history of a bicuspid aortic valve with aortic stenosis, short stature, hearing loss, and mild learning disabilities. Upon examination he was noted to have dysmorphic features and brachydactyly of his fingers and toes. His head circumference was 54.5 cm (25th-50th centile) and his height was 161.3 cm (31st centile) after growth hormone therapy. A skeletal survey noted numerous abnormalities prompting suspicion for Feingold syndrome. A comparative genomic hybridization microarray was completed and a ∼3.6 Mb interstitial heterozygous deletion at 13q31.3 including MIR17HG was found consistent with Feingold syndrome-2. Clinically, this patient has the characteristic digital anomalies and short stature often seen in Feingold syndrome-2 with less common features of a congenital heart defect and hearing loss. Although non-skeletal features have been occasionally reported in Feingold syndrome-1, only one other patient with a 13q31 microdeletion including MIR17HG has had non-skeletal manifestations. Additionally, our patient does not have microcephaly and, to our knowledge, is the first reported pediatric patient with Feingold syndrome-2 without this feature. This report illustrates significant phenotypic variability within the clinical presentation of Feingold syndrome-2 and highlights considerable overlap with Feingold syndrome-1.

Tinea Imbricata in an Italian Child and Review of the Literature

Tinea imbricata is a chronic superficial mycosis caused by Trichophyton concentricum. It is characterized by widespread, annular, concentric, squamous lesions. Tinea imbricata is endemic in three geographical areas: Southwest Pacific, Southeast Asia, and Central and South America. Tinea imbricata in travelers returning from endemic areas is exceptionally rare. We report a case of tinea imbricata in an Italian child who acquired the infection during a trip to Solomon Islands. Three cultures were positive for T. concentricum. The patient was successfully treated with griseofulvin and terbinafine cream.

Total saponins from Discorea nipponica makino ameliorate urate excretion in hyperuricemic rats

Objective:

The objective was to study the mechanism of reducing level of the uric acid by rhizoma dioscoreae nipponese.

Materials and Methods:

A total of 40 rats were divided into four groups: A normal group, hyperuricemia group, benzbromarone group (9 mg/kg) and total saponins from rhizoma dioscoreae nipponese (TDN) group (40 mg/kg). Adenine (100 mg/kg) and ethambutol (250 mg/kg) were used to induce hyperuricemic rats. Immunohistochemical and Western blotting methods were used to detect the mRNA and proteins expressions of rat organic anion transporter1 (rOAT1), rat organic anion transporter3 (rOAT3) and rat urate transporter1 (rURAT1) in the kidneys of different groups.

Results:

It was found that the reduced concentration of blood uric acid was due to the enhancement of renal uric acid excretion. It was realized by up-regulating proteins expressions of rOAT1 and rOAT3 and down-regulating of rURAT1.

Conclusion:

The findings suggested that there were uricosuric effects of TDN by regulating renal organic ion transporters in hyperuricemic animals. Altogether, TDN may be a good Chinese herb in treating hyperuricemia, even a potential drug for gouty arthritis.