Ichthyosis, psoriasiform dermatitis, and recurrent fungal infections in patients with biallelic mutations in PERP

BACKGROUND

Germline autosomal dominant and autosomal recessive mutations in PERP, encoding p53 effector related to PMP-22 (PERP), a component of epidermal desmosomes, have been associated with a spectrum of keratodermas. Monoallelic nonsense mutations cause Olmsted syndrome with severe periorificial keratoderma and palmoplantar keratoderma (PPK). Biallelic recessive frameshift and missense mutations are associated with milder forms of the disease, including generalised erythrokeratoderma and PPK.

OBJECTIVES

To add new insights into the genotype-phenotype correlations as a consequence of PERP mutations and to provide a comprehensive review of the literature.

METHODS

Among 26 previously unresolved families within a cohort of 180 extended Iranian families with syndromic or non-syndromic ichthyosis, two families with shared clinical features were examined by whole-exome sequencing and genome-wide homozygosity mapping. Mycological and dermatopathological studies were performed to further characterise their atypical phenotypic presentations.

RESULTS

In two unrelated multiplex consanguineous families affected by ichthyosis, two novel biallelic PERP variants, NM_022121.5, c.89T > C, p.Leu30Pro and c.466G > C, p.Gly156Arg, located inside of genomic homozygosity regions of the probands were detected. Interestingly, some patients had areas of scaly psoriasiform plaques on the background of generalised ichthyosis that appeared during active cutaneous fungal infections. Mycological examinations of these lesions revealed infections caused by Candida albicans, Epidermophyton floccosum, or Trichophyton rubrum. Histopathology of the psoriasiform lesions shared some features with psoriasis, which when combined with clinical presentation, led to incorrect diagnosis of guttate psoriasis or pustular psoriasis.

CONCLUSIONS

PERP variants in ichthyosis patients can confer susceptibility to recalcitrant cutaneous fungal infections. Additionally, patients with episodic psoriasiform dermatitis in the setting of keratoderma should be considered for PERP genotyping and cutaneous fungal examinations.

Molecular genetic diagnosis of Glanzmann syndrome in Iranian population; reporting novel and recurrent mutations

BACKGROUND

Glanzmann thrombasthenia (GT) is a rare autosomal recessive abnormality of platelet aggregation with quantitative and/or qualitative abnormality of αIIbβ3 integrin. The αIIbβ3 is a platelet fibrinogen receptor, which is required for platelet aggregation, firm adhesion, and also spreading. The disease is more prevalent in the populations with a higher rate of consanguineous marriages as in some Middle Eastern populations including Iraq, Jordan, and Iran. Different types of mutations in ITGA2B and ITGB3 genes have been previously reported to cause the disease.

RESULT

In this study, 16 patients with the clinical diagnosis of GT were studied. Direct sequencing of the exons and exon-intron boundaries of the above genes revealed mutations in 14 patients (detection rate: 87.5%). Briefly, out of fifteen types of identified mutations, 14 were novel. Seven mutations in the ITGB3 gene included 4 missense [c.2T > C, c.155 G > T, c. 538 G > A, c.1990 G > T], one nonsense mutation [c.1303 G > T], a small deletion [c.1656_1658delCTC] and a deletion of one nucleotide [c.401delA]. Mutations in the ITGA2B were 8 different mutations consisting 2 missense [c.286 T > A, c.842 C > T], 2 deletions [c.1899 del T, c.189-319_236del], an insertion [c.1071_1072insG] and one splice site mutations [c.409-3 C > G], one synonymous mutation that might alter the normal splicing process [c.1392 A > G] and a nonsense mutation [c.1555 C > T]. The causative mutation in 2 patients remained unknown. Using long-range PCR and sequencing, we found a rather large deletion. The break point of this deletion covers 319 nt from the last part of the first intron and 48 nt from the beginning of the second exon of ITGA2B gene. The deletion was also detected in two unrelated patients with the same ethnicity. In addition, in silico analyses of novel mutations were performed.

CONCLUSION

There was no recurrent mutation in the studied population. This may be due to either small sample size or the heterogeneity of the studied population.

Development and implementation of a novel panel consisting 20 markers for the detection of genetic causes of male infertility

Azoospermia factor (AZF) genes are involved in spermatogenesis. Deletions in the region of these genes have been recognised as a major genetic cause of infertility due to defects in spermatogenesis. Klinefelter syndrome (KS) is the other main cause of male infertility. This study was performed to establish a novel method for the detection of genetic causes of infertility in males and also to investigate the prevalence, extent and position of Y chromosome microdeletions in Iranian infertile men. We developed a newly designed panel of fluorescent multiplex-PCR method to amplify 20 markers (15 sequence-tagged sites (STSs) markers which are placed in the Y chromosome AZF region, 2 short tandem repeats (STRs) and 3 segmental duplications (SDs)). This multifunctional method is for the simultaneous detection of Y chromosome microdeletions and KS. Among 149 studied infertile men, one was detected to suffer from KS and seven (4.7%) were detected with the presence of one or more deleted STS loci. The main cause of infertility for the remaining patients would be nongenetic factors. This strategy is represented as a fast and accurate method to determine the frequencies of different AZF microdeletions which are suitable for use in clinical purposes.

Multipotent mesenchymal stromal cells: optimization and comparison of five cationic polymer-based gene delivery methods

BACKGROUND

Multipotent mesenchymal stromal cells (MSC) are promising candidates in the field of regenerative medicine and in several studies have been genetically modified to bring a new property to or enhance an existing one in these cells. Furthermore, MSC have been used as gene delivery vehicles. The success of these experiments depends on selecting an appropriate method for gene delivery to the cells.

METHODS

MSC were isolated from rat bone marrow; their authenticity was checked by differentiation experiments as well as staining for cell-surface markers. A systematic approach was used to optimize five cationic polymer-based gene delivery methods (Lipofectamin2000, Effecten, Superfect, Polyfect and FuGENE HD). The transfection yield and cell viability of each method was measured after 48 h in three to six separate experiments with nine to 12 different ratios and amounts of DNA/transfection reagent.

RESULTS

The isolated MSC were successfully differentiated to osteoblasts, adipocytes and chondroblasts. They were positive for rat CD90 and CD73 and negative for CD31, CD45, CD11b and VEGFR2 markers. The average transfection rates with optimum conditions were 5.18+/-2.72 (FuGENE HD), 8.72+/-4.52 (Effecten), 9.59+/-3.12 (Superfect), 16.29+/-7.44 (Polyfect) and 19.60+/-3.12 (Lipofectamine 2000). The toxicity was below 20% for all reagents.

DISCUSSION

Moderate levels of transfection and acceptable cell viability could be achieved using Lipofectamine 2000 and Polyfect in optimized conditions. The results could be improved by gating and sorting live cells using a simple FSC-SSC gating.

A novel single step double positive double negative selection strategy for β-globin gene replacement

beta-Thalassemias are a heterogeneous group of autosomal recessive disorders, characterized by reduced or absence of the beta-globin chain production by the affected alleles. Transplantation of genetically corrected autologous hematopoietic stem cell (HSC) is an attractive approach for treatment of these disorders. Gene targeting (homologous recombination) has many desirable features for gene therapy due to its ability to target the mutant genes and restore their normal expression. In the present study, a specific gene construct for beta-globin gene replacement was constructed consisting of: two homologous stems including, upstream and downstream regions of beta-globin gene, beta-globin gene lying between hygromycin and neomycin resistant genes as positive selection markers and thymidine kinase expression cassettes at both termini as negative selection marker. All segments were subcloned into pBGGT vector. The final plasmid was checked by sequencing and named as pFBGGT. Mammalian cell line COS-7 was transfected with linear plasmid by lipofection followed by positive and negative selection. DNA of the selected cells was analyzed by PCR and sequencing to confirm the occurrence of homologous recombination. In this novel strategy gene replacement was achieved in one step and by a single construct.

Carrier testing and prenatal diagnosis of haemophilia B by SSCP in an Iranian family

Haemophilia B is an X-linked recessive bleeding disorder caused by multiple molecular defects in factor IX gene. During our genotyping programme of haemophilia B patients, a family from the west of Iran was referred to us. We first detected the mutation in the index case of the family by single-strand conformation polymorphism (SSCP) technique. This technique was then applied in carrier detection and prenatal diagnosis for females of this family. Sequencing later revealed the mutation as being G to A at 20519.

Molecular characterisation and three-dimensional structural analysis of mutations in 21 unrelated families with inherited factor VII deficiency

Factor VII (FVII) is a four-domain glycoprotein that plays a critical role in the initiation of blood coagulation. Hereditary deficiencies of this plasma protein results in a bleeding diathesis that varies in severity amongst affected patients. We have analysed the FVII gene in 27 patients with FVII deficiency from 21 unrelated families predominantly of Middle-Eastern extraction. A total of 19 different mutations were identified, of which 12 were novel and 7 had been previously reported. Nine of the 12 novel mutations were missense mutations located in the Gla domain (Ser23Pro), the second epidermal growth factor domain (Cys135Arg) and the catalytic serine protease domain (Arg247Cys, Arg277Cys, Ser282Arg, Pro303Thr, Ser363Ile, Trp364Cys, Trp364Phe), of which five are homozygous. Three novel splice mutations were identified in intron 1a (IVS1a+5), intron 2 (IVS2+1) and intron 6 (IVS6+1). Of the seven previously reported mutations, five were missense mutations of which three are homozygous (Gln100Arg, Arg152Gln, Arg304Gln, Cys310Phe and Thr359Met), one was a 17 bp deletion (10585del117bp) and one was a splice site mutation within intron 7 (IVS7+7). This study has significantly extended the current database of FVII mutations, including the number of known homozygous mutations. Conformational analyses of crystal structures for FVIIa and the FVIIa-tissue factor complex provided likely explanations for the effect of the missense mutations on FVIIa secretion or function. In particular, since 23 missense mutations were located to the serine protease domain, mostly to the region between the catalytic triad and the contact surface with tissue factor, this showed that the orientation of the serine protease domain relative to bound tissue factor in the complex is crucial for functional activity.

Missense mutations in the human beta fibrinogen gene cause congenital afibrinogenemia by impairing fibrinogen secretion

Congenital afibrinogenemia is a rare autosomal recessive disorder characterized by bleeding that varies from mild to severe and by complete absence or extremely low levels of plasma and platelet fibrinogen. Although several mutations in the fibrinogen genes associated with dysfibrinogenemia and hypofibrinogenemia have been described, the genetic defects of congenital afibrinogenemia are largely unknown, except for a recently reported 11-kb deletion of the fibrinogen Aalpha-chain gene. Nevertheless, mutation mechanisms other than the deletion of a fibrinogen gene are likely to exist because patients with afibrinogenemia showing no gross alteration within the fibrinogen cluster have been reported. We tested this hypothesis by studying the affected members of two families, one Italian and one Iranian, who had no evidence of large deletions in the fibrinogen genes. Sequencing of the fibrinogen genes in the 2 probands detected 2 different homozygous missense mutations in exons 7 and 8 of the Bbeta-chain gene, leading to amino acid substitutions Leu353Arg and Gly400Asp, respectively. Transient transfection experiments with plasmids expressing wild-type and mutant fibrinogens demonstrated that the presence of either mutation was sufficient to abolish fibrinogen secretion. These findings demonstrated that missense mutations in the Bbeta fibrinogen gene could cause congenital afibrinogenemia by impairing fibrinogen secretion. (Blood. 2000;95:1336-1341)

Type II protein C deficiency: identification and molecular modelling of two natural mutants with low anticoagulant and normal amidolytic activity

Two mutations in exons 3 and 9 of the protein C gene were identified by amplification and sequencing from symptomatic probands referred for venous thromboembolism and thrombophilia screening. The phenotype associated with the mutations is a type II protein C deficiency with normal amidolytic activity. In one family, the mutation in exon 3 (G3545-->A), which predicts an R9 to H substitution in the Gla domain, was identified. A mutation in exon 9 (G10899-->A), which predicts an R352 to W substitution in the catalytic site, was identified in the second family and has been reported previously in association with type II deficiency with low amidolytic activity. Western blotting of the purified proteins from the probands' plasma did not show any abnormal migratory pattern. Molecular modelling suggested a possible impairment in the recently described Na+ binding pocket for the R352-->W mutant. No conclusions could be drawn relative to the R9-->H mutant.

A novel polymorphism in intron 1a of the human factor VII gene (G73A): study of a healthy Italian population and of 190 young survivors of myocardial infarction

We have identified a novel polymorphism located in intron 1a of the human factor VII gene, caused by the nucleotide change G to A at position + 73. In a population of 128 healthy individuals from northern Italy, the variant A73 allele had a frequency of 0.21, whereas the frequency of the previously reported 10 bp insertion allele located at -323 in the promoter region was 0.17 and that of the Q353 allele in the catalytic region of the factor VII gene was 0. 20. In 75% of the healthy individuals, the A73 allele was present together with the 10 bp insertion and the Q353 alleles, indicating a strong linkage disequilibrium. The concomitant presence of A73 with both the 10 bp and the Q353 alleles was associated with the lowest factor VII levels, measured as coagulant activity, activated factor VII and factor VII antigen. The G73A polymorphism was also evaluated in 190 survivors of myocardial infarction who had experienced the event before the age of 45 years and in 179 individuals with a negative exercise test matched with patients for sex, age and geographical origin. Patients carrying the A73 allele associated with lower factor VII levels tended to have a lower risk of myocardial infarction (adjusted odds ratio 0.54; 95% confidence intervals 0.29-0.99). In conclusion, we found a novel variant allele in intron 1a of the human factor VII gene that is often associated in healthy individuals with the 10 bp and Q353 alleles in the promoter and catalytic region of the same gene. This intronic mutation, alone or in association with other factor VII gene polymorphisms, might confer protection against myocardial infarction in the young.

Gly319 --> arg substitution in the dysfunctional prothrombin Segovia

The molecular defect of a congenitally dysfunctional form of prothrombin, prothrombin Segovia, was identified in a patient with a severe bleeding tendency, reduced prothrombin coagulant activity, and normal antigen level. Nucleotide sequencing of amplified DNA revealed a G --> A change at nucleotide 7539 of exon 9 of the prothrombin gene. This resulted in the substitution of Gly319 by Arg. The proband was homozygous for this mutation, his father and brother were heterozygous. We surmised that the substitution, which occurs near the site of cleavage of prothrombin by factor Xa (Arg320-Ile321), altered the conformation of the protein making the cleavage site inaccessible.

Congenital factor X deficiency: spectrum of bleeding symptoms in 32 Iranian patients

The spectrum of the clinical manifestations of congenital factor X deficiency was studied in 32 Iranian patients. The most frequent symptom was epistaxis, which occurred in 72% of patients, with all degrees of deficiency. Other mucosal haemorrhages (e.g. haematuria, gastrointestinal bleeding) were less frequent and occurred mainly in patients with unmeasurable factor X. Menorrhagia occurred in half of the women of reproductive age. Soft tissue bleeding occurred in two-thirds of the patients; spontaneous haematomas and haemarthroses led to severe arthropathy in five patients. Bleeding from the umbilical stump was an unexpected finding in nine patients. This study demonstrated that the bleeding tendency of factor X deficiency is severe and correlates with factor levels.

The locus for combined factor V-factor VIII deficiency (F5F8D) maps to 18q21, between D18S849 and D18S1103

Combined factor V-factor VIII deficiency (F5F8D) is a rare, autosomal recessive coagulation disorder in which the levels of both coagulation factor V and coagulation factor VIII are diminished. In order to map and subsequently clone the gene responsible for this phenotype, DNAs from 19 families (16 from Iran, 2 from Pakistan, and 1 from Algeria) with a total of 32 affected individuals were collected for a genomewide linkage search using genotypes of highly informative DNA polymorphisms. All pedigrees except two contained at least one consanguineous marriage. A maximum LOD score (Zmax) of 14.82 for theta = .02 was generated with marker D18S1129 in 18q21; LOD scores > 9 were obtained for several other markers-D18S849, D18S1103, D18S64, and D18S862. Multipoint analysis resulted in Zmax = 18.91 for the interval between D18S1129 and D18S64. Informative recombinants placed the locus for F5F8D between D18S849 and D18S1103, in an interval of approximately 1 cM. These results are similar to the recently reported linkage of this disease to chromosome 18q in Jewish families (Nichols et al. 1997) and provide evidence that the same gene is responsible for all F5F8D among human populations. The difference in clinical severity of the phenotype in unrelated families, as well as the failure to detect a specific haplotype of DNA polymorphisms in the consanguineous Iranian families, suggests the existence of different molecular defects in the F5F8D gene. There exists an apparently gap-free contig with CEPH YACs linking the two markers on either side of the critical region. Positional cloning efforts are now in progress to clone the F5F8D gene.

Molecular cloning and expression of human trophoblast antigen FDO161G and its identification as 3 beta-hydroxy-5-ene steroid dehydrogenase

The monoclonal antibody FDO161G reacts with a 43-kDa protein found in human extravillous trophoblast, syncytiotrophoblast, adrenal cortex, interstitial cells of the testis and ovarian follicle cumulus cells. cDNAs for this protein have been isolated from the lambda gt11 library, sequenced, and expressed in COS-7 cells. The protein was identified as 3 beta-hydroxy-5-ene steroid dehydrogenase (HSD). The sequence of the HSD protein raises questions about its association with cell membrane systems. The lack of reactivity of FDO161G with other tissues suggests that HSD has a limited tissue distribution and that other enzymes may exist in peripheral tissues, which can convert delta 5 3-hydroxysteroids to delta 4 3-ketosteroids.