Genetic variants of <Emphasis Type="Italic">CYP1B1</Emphasis> and <Emphasis Type="Italic">WDR36</Emphasis> in the patients with primary congenital glaucoma and primary open angle glaucoma from saint-Petersburg

In 32 unrelated patients with primary congenital glaucoma (PCG), a search for mutations in the myocilin (MYOC), cytochrome P450B1 (CYP1B1), and WDR36 genes was performed. The Q368X mutation in myocilin gene, typical of the patients with adult-onset primary open-angle glaucoma (POAG), was not detected in the PCG patients. Screening of the CYP1B1 introns 2 and 3 for the presence of mutations in PCG patients revealed only six DNA polymorphisms, including IVS1-12ntT>C (g.3793 T>C), A119S (g.4160 G>T; GCC>TCC), G188G (g.4369 C>A; GGC>GGA), L432V (g.8131 C>G; CTG>GTG), D449D (g.8184 C>T; GAC>GAT), and N453S (g.8195 A>G; AAC>AGC) (nucleotide numbering is given in accordance with the GenBank sequence U56438). In the groups of PCG patients and donors without eye diseases, the frequencies of these variants were not statistically significantly different, pointing to the neutrality of these polymorphisms. Furthermore, the CYP1B1 polymorphism L432V, considered to be associated with POAG in some world populations, was not associated with this disease in the patients from St. Petersburg. DNA collections obtained from the POAG and PCG patients and from the control group were tested for the carriage of the worldwide distributed mutations of the WRD36 gene, D658G, R529Q, A449T, and N355S. D658G variant was found with equally low frequencies in the groups of POAG and PCG patients, as well as in the control group. Mutations A449T and R529Q were found only once each, while mutation N355S was not detected in any of the groups examined. Our results indicate that the WDR36 variants make no substantial contribution to the development of POAG and PCG in the patients from St. Petersburg and represent normal DNA polymorphism. It is likely that in most of the PCG patients from the population examined the disease is not associated with the CYP1B1 gene defects.     

Polymorphic Variation of CYP1A1 and CYP1B1 Genes in a Haryana Population

Cytochrome P450 (CYP) 1A1 and CYP1B1 are important phase I xenobiotic metabolizing enzymes involved in the metabolism of numbers of toxins, endogenous hormones, and pharmaceutical drugs. Polymorphisms in these phase I genes can alter enzyme activity and are known to be associated with cancer susceptibility related to environmental toxins and hormone exposure. Their genotypes may also display ethnicity-dependent population frequencies. The present study was aimed to determine the frequencies of commonly known functional polymorphisms of CYP1A1 and CYP1B1 genes in a Haryana state population of North India. The allelic frequency of CYP1A1 polymorphism m1 (MspI) was 29.65% and m2 (Ile⁴⁶²Val) was 24.85%. The frequency of CYP1B1 polymorphism m1 (Val⁴³²Leu) was 45.85% and m2 (Asn⁴⁵³Ser) was 16.2%. We observed inter- and intra-ethnic variation in the frequency distribution of these polymorphisms. Analysis of polymorphisms in these genes might help in predicting the risk of cancer. Our results emphasize the need for more such studies in high-risk populations.     

Mutations in CYP1B1, the gene for cytochrome P4501B1, are the predominant cause of primary congenital glaucoma in Saudi Arabia.

The autosomal recessive disorder primary congenital glaucoma (PCG) is caused by unknown developmental defect(s) of the trabecular meshwork and anterior chamber angle of the eye. Homozygosity mapping with a DNA pooling strategy in three large consanguineous Saudi PCG families identified the GLC3A locus on chromosome 2p21 in a region tightly linked to PCG in another population. Formal linkage analysis in 25 Saudi PCG families confirmed both significant linkage to polymorphic markers in this region and incomplete penetrance, but it showed no evidence of genetic heterogeneity. For these 25 families, the maximum combined two-point LOD score was 15.76 at a recombination fraction of .021, with the polymorphic marker D2S177. Both haplotype analysis and homozygosity mapping in these families localized GLC3A to a 5-cM critical interval delineated by markers D2S2186 and D2S1356. Sequence analysis of the coding exons for cytochrome P4501B1 (CYP1B1) in these 25 families revealed three distinctive mutations that segregate with the phenotype in 24 families. Additional clinical and molecular data on some mildly affected relatives showed variable expressivity of PCG in this population. These results should stimulate a study of the genetic and environmental events that modify the effects of CYP1B1 mutations in ocular development. Furthermore, the small number of PCG mutations identified in this Saudi population makes both neonatal and population screening attractive public health measures.     

A Novel Methodology for Enhanced and Consistent Heterologous Expression of Unmodified Human Cytochrome P450 1B1 (CYP1B1)

Cytochrome P450 1B1 (CYP1B1) is a universal cancer marker and is implicated in many other disorders. Mutations in CYP1B1 are also associated with childhood blindness due to primary congenital glaucoma (PCG). To understand the CYP1B1 mediated etiopathology of PCG and pathomechanism of various cancers, it is important to carry out its functional studies. Heterologous expression of CYP1B1 in prokaryotes is imperative because bacteria yield a higher amount of heterologous proteins in lesser time and so the expressed protein is ideal for functional studies. In such expression system there is no interference by other eukaryotic proteins. But the story is not that simple as expression of heterologous CYP1B1 poses many technical difficulties. Investigators have employed various modifications/deletions of CYP N-terminus to improve CYP1B1 expression. However, the drawback of these studies is that it changes the original protein and, as a result, invalidates functional studies. The present study examines the role of various conditions and reagents in successful and consistent expression of sufficient quantities of unmodified/native human CYP1B1 in E. coli. We aimed at expressing CYP1B1 in various strains of E. coli and in the course developed a protocol that results in high expression of unmodified protein sufficient for functional/biophysical studies. We examined CYP1B1 expression with respect to different expression vectors, bacterial strains, types of culture media, time, Isopropyl β-D-1-thiogalactopyranoside concentrations, temperatures, rotations per minute, conditioning reagents and the efficacy of a newly described technique called double colony selection. We report a protocol that is simple, easy and can be carried out in any laboratory without the requirement of a fermentor. Though employed for CYP1B1 expression, this protocol can ideally be used to express any eukaryotic membrane protein.     

Mutational analysis of CYP1B1 (rs56010818) variant in primary open angle glaucoma (POAG) affected patients of Pakistan

BackgroundPrimary open angle glaucoma (POAG) occurs due to the discrepancies in the angle of anterior chamber characterized by the alterations in intraocular pressure, optic nerves head changes and central loss of visual field. In molecular research, CYP1B1 mutations modulates an integral role in association with glaucoma. Current study was undertaken to reveal the homozygous and heterozygous patterns of CYP1B1 c.1169 G > A variant (rs56010818) in POAG patients of Pakistan.MethodsAfter consent, total n = 88 POAG patients undergone through standard ophthalmological investigations before their recruitment in this study. The blood samples were utilized for DNA isolation. The genotyping of CYP1B1 c.1169 G > A variant was carried out by Sanger sequencing. The mutational patterns and its association with clinical variables were demonstrated by statistical and bioinformatic tools.ResultsIt was evident that the frequencies of heterozygous G/A and homozygous mutants A/A genotypes were higher in males (36.5%, 7.7%) than females (30.6%, 2.8%) of POAG population. Furthermore, the juvenile patients exhibit high manifestation of carrier genotype (66.6%) in comparison to adult patients (31.7%). The results also indicated the significant relationship of intraocular pressure with homozygous mutant A/A genotype of CYP1B1 variant in POAG patients (p < 0.05).ConclusionsOur study provided the mutational data of CYP1B1 R390H variant and the patterns of homozygosity and heterozygosity along with clinical associations. Overall, this study revealed the genetic predisposition of CYP1B1 c.1169 G > A variant in the patients of POAG in Pakistan. The findings could be helpful for genetic screening and in-depth understanding of underlying causes in the pathogenesis of POAG.     

Sequence analysis and homology modeling suggest that primary congenital glaucoma on 2p21 results from mutations disrupting either the hinge region or the conserved core structures of cytochrome P4501B1.

We recently reported three truncating mutations of the cytochrome P4501B1 gene (CYP1B1) in five families with primary congenital glaucoma (PCG) linked to the GLC3A locus on chromosome 2p21. This could be the first direct evidence supporting the hypothesis that members of the cytochrome P450 superfamily may control the processes of growth and differentiation. We present a comprehensive sequence analysis of the translated regions of the CYP1B1 gene in 22 PCG families and 100 randomly selected normal individuals. Sixteen mutations and six polymorphisms were identified, illustrating an extensive allelic heterogeneity. The positions affected by these changes were evaluated by building a three-dimensional homology model of the conserved C-terminal half of CYP1B1. These mutations may interfere with heme incorporation, by affecting the hinge region and/or the conserved core structures (CCS) that determine the proper folding and heme-binding ability of P450 molecules. In contrast, all polymorphic sites were poorly conserved and located outside the CCS. Northern hybridization analysis showed strong expression of CYP1B1 in the anterior uveal tract, which is involved in secretion of the aqueous humor and in regulation of outflow facility, processes that could contribute to the elevated intraocular pressure characteristic of PCG.     

Divergent Gender Identity in Three Siblings With 46Xx Karyotype and Severely Virilizing Congenital Adrenal Hyperplasia Caused by A Novel Cyp11B1 Mutation

ObjectiveTo describe conflicting gender identities in three karyotypically female siblings with congenital adrenal hyperplasia (CAH) caused by a novel mutation in the CYP11B1 gene, who were assigned as males at birth and followed up to adulthood.MethodsWe present 3 siblings (16, 14 and 10 years old) who were born with severe genital virilization and raised as males. Clinical examination showed Prader IV to V external genitalia with a stretched penile length of 7 to 11 cm. Adrenocorticotrophic hormone (ACTH) stimulation test showed a stimulated 11 deoxycortisol (11DOC) level of 12,300-18,700 μg/L (normal 0-5 μg/L). Their karyotypes were 46 XX, and they had normal-sized uterus and ovaries on pelvic ultrasound. DNA was isolated from peripheral leukocytes, and polymerase chain reaction (PCR) and direct sequencing revealed a novel CYP11B1 mutation. This mutation leads to a c.53_54 T insertion (c.53_54insT) with frameshift and truncation at c.115 (codon 39) of CYP11B1.ResultsPsychological evaluation of the oldest sibling suggested a female gender identity, and she declared herself as female, and female sex was re-assigned after 1 year of psychosocial adjustment. Psychological assessment for the 2 younger siblings and a fourth 46XY sibling with the same condition revealed male gender identities, and they continued their lives as males without significant difficulties.ConclusionDivergent gender identity was observed in three severely masculinized 46XX siblings with CAH who carried the same CYP11B1 mutation and had comparable postnatal and probably prenatal androgen exposure and environmental circumstances. These cases suggest that the basis of gender identity is more complex than chromosomal, biochemical, and genetic constitution. (Endocr Pract. 2014;20:e191-e197)     

Digenic Inheritance of Early-Onset Glaucoma: CYP1B1, a Potential Modifier Gene

"Early-onset glaucoma" refers to genetically heterogeneous conditions for which glaucoma manifests at age 5-40 years and for which only a small subset is molecularly characterized. We studied the role of MYOC, CYP1B1, and PITX2 in a population (n=60) affected with juvenile or early-onset glaucoma from the greater Toronto area. By a combination of single-strand conformation polymorphism and direct cycle sequencing, MYOC mutations were detected in 8 (13.3%) of the 60 individuals, CYP1B1 mutations were detected in 3 (5%) of the 60 individuals, and no PITX2 mutations were detected. The range of phenotypic expression associated with MYOC and CYP1B1 mutations was greater than expected. MYOC mutations included cases of juvenile glaucoma with or without pigmentary glaucoma and mixed-mechanism glaucoma. CYP1B1 mutations involved cases of juvenile open-angle glaucoma, as well as cases of congenital glaucoma. The study of a family with autosomal dominant glaucoma showed the segregation of both MYOC and CYP1B1 mutations with disease; however, in this family, the mean age at onset of carriers of the MYOC mutation alone was 51 years (range 48-64 years), whereas carriers of both the MYOC and CYP1B1 mutations had an average age at onset of 27 years (range 23-38 years) (P=.001). This work emphasizes the genetic heterogeneity of juvenile glaucoma and suggests, for the first time, that (1) congenital glaucoma and juvenile glaucoma are allelic variants and (2) the spectrum of expression of MYOC and CYP1B1 mutations is greater than expected. We also propose that CYP1B1 may act as a modifier of MYOC expression and that these two genes may interact through a common pathway.     

Investigation of CYP21A2 mutations in Turkish patients with 21-hydroxylase deficiency and a novel founder mutation

Congenital adrenal hyperplasia (CAH) is a group of autosomal recessively inherited disorders characterized by impaired production of adrenal steroids. Approximately 95% of all CAH are caused by mutations of the CYP21A2 that encodes 21-hydroxylase. In this study, mutation analyses of CYP21A2 were performed in 48 CAH patients from 45 Turkish families with the clinical diagnosis of 21-hydroxylase deficiency (21OHD). While in 39 (86.7%) of 21OHD patients, disease causing CYP21A2 mutations were identified in both alleles, in two 21OHD patients CYP21A2 mutations were identified only in one allele. In four patients, mutation was not detected at all. In total, seventeen known and one novel, disease causing CYP21A2 mutations were observed. Among identified mutations, previously described c.293-13C/A>G, large rearrangements and p.Q319X mutations were the most common mutations accounting for 33.3%, 14.4% and 12.2% of all evaluated chromosomes, respectively. In six families (13.3%) a novel founder mutation, c.2T>C (p.M1?), inactivating the translation initiation codon was found. This mutation is not present in pseudogene CYP21A1P and causes the classical form of the disease in six patients. In addition, depending on the nature of the rearrangements CYP21A1P/CYP21A2 chimeras were further classified as CH^c/d, and CH-1^c was shown to be the most prominent chimera in our study group. In conclusion, with this study we identified a novel founder CYP21A2 mutation and suggest a further classification for CYP21A1P/CYP21A2 chimeras depending on the combination of junction site position and whether it is occurred as a result of deletion or conversion. Absence of disease causing mutation of CYP21A2 in ten of screened ninety chromosomes suggests the contribution of regulatory elements in occurrences of CAH due to the 21OHD.     

A Case of “Late-Onset” Idiopathic Infantile Hypercalcemia Secondary to Mutations in the CYP24A1 Gene

ObjectiveMutations in the 24-hydroxylase gene, CYP24A1, have recently been reported to cause idiopathic infantile hypercalcemia (IIH), a rare disease presenting in the first year of life that is characterized by increased sensitivity to vitamin D, leading to severe symptomatic hypercalcemia.MethodsWe present a case report and review the relevant literature.ResultsA 24-year-old Caucasian man presented with repetitive signs of nephrolithiasis since the age of 18 years, hypercalciuria (17.1 mmol/24 h), slightly elevated serum calcium concentration (2.64 mmol/L), and inappropriately high levels of 1,25-dihydroxyvitamin D (101 pg/mL) in combination with suppressed levels of circulating parathormone (7.9 pg/mL). Exogenous vitamin D intoxication as well as granulomatous disease or malignancy were excluded. Genetic analysis revealed a loss-of-function mutation in CYP24A1. Of note, our patient denied any prior clinical signs of impaired calcium homeostasis during childhood.ConclusionHere, we describe the exceptional case of a patient with hypercalciuria and recurrent nephrolithiasis secondary to mutations in CYP24A1, without any signs of IIH in childhood, indicating that the phenotypic spectrum includes mild “late-onset” disease that becomes symptomatic in adolescence. Therefore, reduced CYP24A1 activity should be considered as a possible reason for recurrent nephrolithiasis in adults. (Endocr Pract. 2014;20: e91-e95)     

Molecular Analysis and Phenotypic Study in 14 Chinese Families with Bietti Crystalline Dystrophy

Purpose

To investigate the clinical features and cytochrome P450 family 4 subfamily V polypeptide 2 (CYP4V2) gene mutations in 14 Chinese families with Bietti crystalline dystrophy (BCD).

Methods

Seventeen patients from 14 unrelated Chinese families with BCD were recruited for complete clinical ophthalmic examination and genetic study. The 11 exons of CYP4V2 were amplified from genomic DNA of all patients and their family members by polymerase chain reaction (PCR) and then sequenced. Exons of TIMP3 were also sequenced in BCD patient associated with choroidal neovascularization (CNV). One hundred and seventy unrelated healthy Chinese subjects were screened for mutations in CYP4V2.

Results

All 17 patients with BCD had mutations in CYP4V2; one of these mutations was novel (c.219T>A, p.F73L) and four other mutations had been reported. The p.F73L mutation was a commonly detected mutation in our study (seven out of 34 alleles), either in the homozygous state or in the heterozygous state. Among the patients, considerable phenotypic variability was detected, both within and between families. Screening of TIMP3 did not find any mutation in the BCD patient associated with CNV.

Conclusion

The novel CYP4V2 c.219T>A (p.F73L) mutation may be another recurrent mutation in Chinese patients with BCD. Our study expands the mutation spectrum of CYP4V2 and characterizes novel genotype–phenotype associations in Chinese patients with BCD.     

Investigation of the FSHR,CYP11, and INSR Mutations and Polymorphisms in Iranian Infertile Women with Polycystic Ovary Syndrome (PCOS)

Background:Polycystic ovary syndrome (PCOS) is the most common cause of ovarian dysfunction associated with infertility, Oligomenorrhea or amenorrhea, hirsutism, acne, and obesity. A large body of evidence unraveled, three major groups of genes play critical roles in underlying PCOS molecular mechanism. The aim of this study is to investigate critical exonic variant of FSHR, CYP11, and INSR and determine the functionality of these mutations in Iranian patients with PCOS.Methods:In this case-control study, 130 patients with PCOS who referred to the Vali-e-Asr Hospital with infertility were included. DNA extracted from three ml of peripheral blood of the participants for DNA extraction. The PCR was conducted for each gene and the PCR product was genotyped by sequencing. Results:The data showed that there were two polymorphisms in INSR genes which did not change the protein sequences; these alterations can also be considered as a single nucleotide polymorphism (SNP). Moreover, any exonic variant has not been detected in CYP11B1. Whereas, two missense mutation have been detected in FSHR gene including p.Ala307Thr and p.Asn680Ser. It has been shown that the polymorphisms of the FSHR gene affect the hormone response in the ovaries. Our data demonstrated that the FSHR mutations frequencies were higher in the patients with PCOS rather than control people significantly.Conclusion:These data showed that the polymorphisms of FSHR were significantly associated with PCOS in Iranian infertile women. Further studies with larger sample sizes are needed to be performed for explore the strength of the association.Key Words: CYP11, FSHR, Infertile, INSR, PCOS, Polymorphisms     

基于在线数据库和真实世界样本探讨肺腺癌患者POLE/POLD1突变的临床意义

摘要 目的：POLE和POLD1突变导致DNA聚合酶校对功能丧失可能会影响基因组稳定性并导致突变增加和肿瘤形成。本文结合在线数据库和真实世界样本进一步分析肺腺癌（LUAD）患者POLE和/或 POLD1 突变的临床意义。方法：纳入2021年1月～2021年8月徐州医科大学附属医院肺癌术后组织标本115例,利用二代测序技术（NGS）检测基因突变;从癌症基因组图谱（TCGA）数据库收集肺腺癌数据集,通过Cbioportal在线数据库获得肿瘤突变分布图,通过Cibersort法计算获得样本的免疫相关细胞浸润情况。结果：真实世界样本中POLE/ POLD1突变的比例为7.83%（9/115）。TCGA数据显示POLE/POLD1突变的LUAD患者总生存期（OS）减少（P=0.0359）。然而,携带该突变的患者并发其他基因改变的频率明显增加,尤其是与TP53突变存在正相关;同时,POLE/POLD1突变与LUAD组织浸润性免疫杀伤细胞呈正相关,与免疫抑制细胞呈负相关,提示这部分患者对免疫检查点抑制剂（ICI）敏感。结论：LUAD患者POLE/POLD1突变预示较高的肿瘤突变负荷和免疫微环境改变,可作为ICI疗效预测的潜在生物标志物,值得临床关注。     

Null Mutations in LTBP2 Cause Primary Congenital Glaucoma

Primary congenital glaucoma (PCG) is an autosomal-recessive condition characterized by high intraocular pressure (IOP), usually within the first year of life, which potentially could lead to optic nerve damage, globe enlargement, and permanent loss of vision. To date, PCG has been linked to three loci: 2p21 (GLC3A), for which the responsible gene is CYP1B1, and 1p36 (GLC3B) and 14q24 (GLC3C), for which the genes remain to be identified. Here we report that null mutations in LTBP2 cause PCG in four consanguineous families from Pakistan and in patients of Gypsy ethnicity. LTBP2 maps to chromosome 14q24.3 but is around 1.3 Mb proximal to the documented GLC3C locus. Therefore, it remains to be determined whether LTBP2 is the GLC3C gene or whether a second adjacent gene is also implicated in PCG. LTBP2 is the largest member of the latent transforming growth factor (TGF)-beta binding protein family, which are extracellular matrix proteins with multidomain structure. It has homology to fibrillins and may have roles in cell adhesion and as a structural component of microfibrils. We confirmed localization of LTBP2 in the anterior segment of the eye, at the ciliary body, and particularly the ciliary process. These findings reveal that LTBP2 is essential for normal development of the anterior chamber of the eye, where it may have a structural role in maintaining ciliary muscle tone.     

Novel Mutations in Dax1 of X-Linked Adrenal Hypoplasia Congenita Over Several Generations in One Family

ObjectiveX-linked adrenal hypoplasia congenital (AHC) is a rare disorder caused by mutations in DAX1 gene. We report a case of X-linked AHC in a large family to analyze the pathogenesis of this rare disease and to add to our clinical knowledge of it.MethodsWe describe 3-year-old boy’s clinical features and laboratory test results, as well as the patient’s nuclear family members’ clinical symptoms, especially those with features of adrenal insufficiency. Genomic deoxyribonucleic acid (DNA) was extracted from the patient’s and the family members’ peripheral blood leukocytes, and the coding region and promoter region of DAX1 were directly sequenced.ResultsA 3-year-old boy who was diagnosed with X-linked AHC presented with atypical symptoms, and his laboratory test results revealed elevated serum adrenocorticotropic hormone levels (ACTH) and decreased serum cortisol levels. Three novel mutations were detected in the DAX1 coding sequence in this family: a missense mutation (c.376G>A, p.Val126Met), a synonymous mutation (c.498G>A, p.Arg166Arg), and a nonsense mutation (c.1225C>T, p.Gln409X).ConclusionsThis report describes the familial transmission of AHC over several generations and further expands the number of DAX1 mutations reported in the literature. Early diagnosis and prompt treatment of X-linked AHC are important and may provide a good prognosis. (Endocr. Pract. 2013;19:e105-e111)