Mutations in CEP78 Cause Cone-Rod Dystrophy and Hearing Loss Associated with Primary-Cilia Defects.

Cone-rod degeneration (CRD) belongs to the disease spectrum of retinal degenerations, a group of hereditary disorders characterized by an extreme clinical and genetic heterogeneity. It mainly differentiates from other retinal dystrophies, and in particular from the more frequent disease retinitis pigmentosa, because cone photoreceptors degenerate at a higher rate than rod photoreceptors, causing severe deficiency of central vision. After exome analysis of a cohort of individuals with CRD, we identified biallelic mutations in the orphan gene CEP78 in three subjects from two families: one from Greece and another from Sweden. The Greek subject, from the island of Crete, was homozygous for the c.499+1G>T (IVS3+1G>T) mutation in intron 3. The Swedish subjects, two siblings, were compound heterozygotes for the nearby mutation c.499+5G>A (IVS3+5G>A) and for the frameshift-causing variant c.633delC (p.Trp212Glyfs(∗)18). In addition to CRD, these three individuals had hearing loss or hearing deficit. Immunostaining highlighted the presence of CEP78 in the inner segments of retinal photoreceptors, predominantly of cones, and at the base of the primary cilium of fibroblasts. Interaction studies also showed that CEP78 binds to FAM161A, another ciliary protein associated with retinal degeneration. Finally, analysis of skin fibroblasts derived from affected individuals revealed abnormal ciliary morphology, as compared to that of control cells. Altogether, our data strongly suggest that mutations in CEP78 cause a previously undescribed clinical entity of a ciliary nature characterized by blindness and deafness but clearly distinct from Usher syndrome, a condition for which visual impairment is due to retinitis pigmentosa.

Whole exome sequencing identifies a heterozygous missense variant in the PRDM5 gene in a family with Axenfeld-Rieger syndrome.

Axenfeld-Rieger syndrome (ARS) is a disorder affecting the anterior segment of the eye, often leading to secondary glaucoma and several systemic malformations. It is inherited in an autosomal dominant fashion that has been associated with genetic defects in PITX2 and FOXC1. Known genes CYP1b1, PITX2, and FOXC1 were excluded by Sanger sequencing. The purpose of current study is to identify the underlying genetic causes in ARS family by whole exome sequencing (WES). WES was performed for affected proband of family, and variants were prioritized based on in silico analyses. Segregation analysis of candidate variants was performed in family members. A novel heterozygous PRDM5 missense variant (c.877A>G; p.Lys293Glu) was found to segregate with the disease in an autosomal dominant fashion. The novel missense variant was absent from population-matched controls, the Exome Variant Server, and an in-house exome variant database. The Lys293Glu variant is predicted to be pathogenic and affects a lysine residue that is conserved in different species. Variants in the PRDM5 gene were previously identified in anterior segment defects, i.e., autosomal recessive brittle cornea syndrome and keratoconus. The results of this study suggest that genetic variants in PRDM5 can lead to various syndromic and nonsyndromic disorders affecting the anterior segment of the eye.

Identification of novel CYP1B1 gene mutations in patients with primary congenital and primary open-angle glaucoma.

BACKGROUND: CYP1B1 is the most commonly mutated gene in primary congenital glaucoma (PCG), and mutations have also been identified in primary open-angle glaucoma (POAG). This study was undertaken to describe mutations in CYP1B1 in patients and families with PCG and POAG from Pakistan. DESIGN: Case-control series. PARTICIPANTS: Forty families, 190 sporadic POAG cases and 140 controls from Pakistan. METHODS: Patients and healthy individuals of one consanguineous Pakistani family were genotyped with high-resolution single nucleotide polymorphism microarrays. Homozygosity mapping was performed using HomozygosityMapper. Direct sequencing of CYP1B1 gene was performed in probands of the families, sporadic POAG cases and control individuals. MAIN OUTCOME MEASURES: Mutations in the CYP1B1 gene in PCG and POAG patients. RESULTS: Homozygosity mapping in a consanguineous Pakistani family revealed one 11-Mb homozygous region encompassing the CYP1B1 gene. A homozygous CYP1B1 missense mutation (p.Arg390His) was identified in this family. Sequence analysis of CYP1B1 in 39 additional families revealed one known and three novel homozygous mutations in PCG (p.Ala288Pro, p.Asp242Ala, p.Arg355* and p.Arg290Profs*37). In POAG, one novel heterozygous missense mutation (p.Asp316Val) was identified in one family and a previously reported mutation (p.Glu229Lys) was identified in three families. Analysis of CYP1B1 in a panel of 190 sporadic POAG patients revealed three novel heterozygous variants (p.Thr234Lys, p.Ala287Pro and p.Gln362*) and three previously reported heterozygous variants (p.Gly61Glu, p.Glu229Lys and p.Arg368His). The p.Glu229Lys variant was significantly associated with POAG (P = 0.03; odds ratio 2.49). CONCLUSIONS: This study confirms that CYP1B1 mutations are associated with POAG and PCG in the Pakistani population.

CYP1B1 mutations in patients with primary congenital glaucoma from Saudi Arabia.

BACKGROUND: CYP1B1 is the most commonly mutated gene in primary congenital glaucoma (PCG). This study was undertaken to identify mutations in CYP1B1 in the Western region of Saudi Arabia. METHODS: Blood of patients who had typical findings of PCG, were screened by direct sequencing of all coding exons and splice junctions of the CYP1B1 gene. RESULTS: 34 patients were studied; 18 patients belonged to 8 families, and 16 patients were non-familial, isolated PCG. Consanguinity was found in 27/34 (79.4%) of cases. All patients were diagnosed to have bilateral PCG at birth except one child, who had glaucoma in the right eye. More males (61.8%) were affected than females (38.2%). 79.4% (27/34) of patients were solved with pathogenic mutations and 20.6% (7/34) remained unsolved. Of the solved ones, 22.2% (6/27) of patients carry a pathogenic allele on one allele while the other allele remained yet to be determined. Direct sequencing of exon 2 revealed two pathogenic variants (p.Gly61Glu, p.Glu229Lys). P.Gly61Glu substitution was found both homozygously in 63% (17/27) of cases, and heterozygously in one patient. P.Glu229Lys variant was found heterozygous in 3.7% (1/27) of cases. One pathogenic variant (p.Arg469Trp) was found in exon 3, and is present homozygously in 14.8% (4/27) of cases while four patients have this variant heterozygously. All mutations were reported previously in the Saudi population, except p.Glu229Lys. Severe cases were associated with p.Gly61Glu, and p.Arg469Trp in 50% and 30% of ten patients respectively. CONCLUSIONS: This study confirms that CYP1B1 mutations are the most frequent cause of PCG in the Saudi population, with p.Gly61Glu being the major disease-associated mutation. P.Glu229Lys is a newly discovered mutation in our PCG patients. Patient lacking mutation in CYP1B1 gene seems likely, to have another genetic loci involved in the pathogenesis of the disease, and need further study. Genetic studies of recessive diseases such as PCG is important in consanguineous populations, since it will increase awareness and allows genetic counseling to be offered to patients and their relatives. This will not only reduce the disease to be inherited to future generations, but will also reduce the disease burden in the community.

Association of known common genetic variants with primary open angle, primary angle closure, and pseudoexfoliation glaucoma in Pakistani cohorts.

PURPOSE: Despite the different etiology of primary open angle glaucoma (POAG), primary angle closure glaucoma (PACG), and pseudoexfoliative glaucoma (PEXG), several studies have suggested that these forms of glaucoma have overlapping genetic risk factors. Therefore, the aim of this study was to evaluate the role of genetic variants recently associated with POAG in different types of glaucoma in Pakistani POAG, PACG, and PEXG patient cohorts. METHODS: Six variants in CDKN2B-AS1 (rs4977756), CDKN2B (rs1063192), ATOH7 (rs1900004), CAV1 (rs4236601), TMCO1 (rs4656461), and SIX1 (rs10483727) were genotyped using TaqMan assays. A total of 513 unrelated patients with glaucoma (268 with POAG, 125 with PACG, and 120 with PEXG) and 233 healthy controls were included in the study. Genotypic and allelic associations were analyzed with a chi-square test. RESULTS: The frequency of the G allele of TMCO1 rs4656461 was significantly lower in the patients with POAG (p=0.003; OR [odds ratio]=0.57), PACG (p=0.009; OR=0.52), and PEXG (p=0.01; OR=0.54) compared to the control individuals. The T allele of ATOH7 rs1900004 was observed less frequently in the patients with PACG (p=0.03; OR=0.69) compared to the control individuals. The A allele of CAV1 rs4236601 was found more frequently in the patients with POAG (p=0.008; OR=1.49) compared to the control individuals. This study demonstrates that the TMCO1 rs4656461 variant is associated with POAG, PACG and PEXG in the Pakistani population. Our study was unable to confirm previous associations reported for variants in CDKN2B-AS1, CDKN2B, and SIX1 with any type of glaucoma. CONCLUSIONS: In conclusion, we found consistent evidence of the significant association of three common variants in TMCO1, ATOH7, and CAV1.

Polymorphisms in matrix metalloproteinases MMP1 and MMP9 are associated with primary open-angle and angle closure glaucoma in a Pakistani population.

PURPOSE: Matrix metalloproteinases (MMPs) play an important role in remodeling of the extracellular matrix during development and growth of various tissues including the eye. Various functional polymorphisms in MMPs have been implicated in the pathogenesis of different types of glaucoma. The aim of the present study was to investigate the role of various polymorphisms in Pakistani patients with glaucoma. METHODS: The present case-control study included 112 patients with primary open-angle glaucoma (POAG), 82 patients with primary angle closure glaucoma (PACG), and 118 control subjects. Genotyping of polymorphisms was done using PCR followed by restriction fragment length polymorphism analysis. RESULTS: A significant difference in the genotype frequencies of MMP1 rs1799750 (-1607 1G/2G) was observed between the patients with POAG and the control subjects (p = 0.001). This was attributed to the female subjects (p < 0.001), while the association was not significant in male subjects (p > 0.47). In addition, a significant difference was observed in genotype frequencies of MMP9 rs17576 (c.836A>G) in patients with PACG compared to the control subjects (p < 0.001), which after gender stratification remained significant in men (p = 0.009) but not in women (p = 0.14). No significant associations were found for MMP7 (c.-181T>C) and MMP9 (c.-1562C>T) polymorphisms. CONCLUSIONS: Our data suggest that the MMP1 rs1799750 (-1607 1G/2G) and MMP9 rs17576 polymorphisms might be of value for further study as potential gender-dependent risk factors for developing POAG and PACG, respectively, in Pakistan.

Exome sequencing identifies a novel and a recurrent BBS1 mutation in Pakistani families with Bardet-Biedl syndrome.

PURPOSE: To determine the genetic cause of Bardet-Biedl syndrome (BBS) in two consanguineous Pakistani families. METHODS: Clinical characterization of the affected individuals in both families was performed with ophthalmic examination, electroretinography, electrocardiography, and liver and renal profiling. Seventeen genes are known to be associated with BBS, so exome sequencing was preferred over candidate gene sequencing. One affected individual from both families was selected for exome sequencing. Segregation of the identified variants was confirmed with Sanger sequencing. RESULTS: Retinitis pigmentosa, obesity, and learning difficulties were present in the affected individuals in both families. In family A, a sixth finger (polydactyly) of the proband's sister was removed by a surgical operation leaving a scar on the little finger. Polydactyly was also present in both affected individuals from family B. All diagnostic symptoms were characteristic of BBS in both families. In both affected individuals from family A, exome sequencing identified a novel homozygous mutation (c.47+1G>T) in BBS1 that inactivates the splice donor site at the end of exon 1. In family B, a previously reported mutation, c.442G>A; p.(Asp148Asn), was detected. CONCLUSIONS: Exome sequencing is an efficient and cost-effective technique for identifying mutations in genetically heterogeneous diseases. In addition, intrafamilial phenotypic variability in family A argues for the modifying effect of other still unknown modifier alleles.

Role of Lysyl oxidase-like 1 gene polymorphisms in Pakistani patients with pseudoexfoliative glaucoma.

PURPOSE: Single nucleotide polymorphisms (SNPs) rs1048661 (p.R141L) and rs3825942 (p.G153D) in the lysyl oxidase-like 1 (LOXL1) gene have been previously reported to be associated with pseudoexfoliation glaucoma (PEXG) in various Asian and European populations, but these SNPs have not yet been studied in the Pakistani population. Therefore the aim of the present study was to investigate the association of these two coding LOXL1 SNPs in Pakistani PEXG patients. METHODS: One hundred twenty-eight Pakistani patients diagnosed with PEXG and 180 healthy controls were recruited for the study. Genomic DNA was extracted and both SNPs were genotyped by direct sequencing. Association of genotype and allele frequencies with PEXG were analyzed using the Chi-square (χ(2)) test. RESULTS: Genotype and allele frequencies of both rs1048661 and rs3825942 were found to be significantly associated with PEXG. The GG genotypes of both LOXL1 SNPs were associated with an increased risk of developing PEXG. In addition the G alleles of rs1048661 and rs3825942 confer an increased risk for PEXG with an odds ratio (OR) of 2.98 (95% CI 1.94-4.57) and OR 6.83 (95% CI 2.94-16.67), respectively. CONCLUSIONS: A significant association was found for the G allele of rs1048661 and rs3825942 in PEXG patients of Pakistani origin.

Identification of a novel FBN1 gene mutation in a large Pakistani family with Marfan syndrome.

PURPOSE: To describe a novel mutation in the fibrillin-1 (FBN1) gene in a large Pakistani family with autosomal dominant Marfan syndrome (MFS). METHODS: Blood samples were collected of 11 family members affected with Marfan syndrome, and DNA was isolated by phenol-extraction. The coding exons of FBN1 were analyzed by polymerase chain reaction (PCR) and direct sequencing. One hundred-thirty controls were screened for a mutation in the FBN1 gene that was identified in this family by restriction fragment length polymorphism (RFLP) analysis. RESULTS: A novel heterozygous missense mutation c.2368T>A; p.Cys790Ser was observed in exon 19. This mutation substitutes a highly conserved cysteine residue by serine in a calcium binding epidermal growth factor-like domain (cbEGF) of FBN1. This mutation was present in all affected members and absent from unaffected individuals of the family in addition to 130 healthy Pakistani controls. Interestingly all affected family members presented with ectopia lentis, myopia and glaucoma, but lacked the cardinal cardiovascular features of MFS. CONCLUSIONS: This is a first report of a mutation in FBN1 in MFS patients of Pakistani origin. The identification of a FBN1 mutation in this family confirms the diagnosis of MFS patients and expands the worldwide spectrum of FBN1 mutations.

Identification of recurrent and novel mutations in TULP1 in Pakistani families with early-onset retinitis pigmentosa.

PURPOSE: To identify the genetic defects underlying retinitis pigmentosa (RP) in Pakistani families. METHODS: Genome-wide high-density single-nucleotide-polymorphism microarray analysis was performed using the DNA of nine affected individuals from two large families with multiple consanguineous marriages. Data were analyzed to identify homozygous regions that are shared by affected sibs in each family. Sanger sequencing was performed for genes previously implicated in autosomal recessive RP and allied retinal dystrophies that resided in the identified homozygous regions. Probands from both families underwent fundus examination and electroretinogram measurements. RESULTS: The tubby-like protein 1 gene (TULP1) was present in the largest homozygous region in both families. Sequence analysis identified a previously reported mutation (c.1138A>G; p.Thr380Ala) in one family and a novel pathogenic variant (c.1445G>A; p.Arg482Gln) in the other family. Both variants were found to be present in a homozygous state in all affected individuals, were heterozygous present in the unaffected parents, and heterozygous present or absent in normal individuals. Affected individuals of both families showed an early-onset form of RP. CONCLUSIONS: Homozygosity mapping, combined with candidate-gene analysis, successfully identified genetic defects in TULP1 in two large Pakistani families with early-onset retinitis pigmentosa.

Targeted gene sequencing of FYCO1 identified a novel mutation in a Pakistani family for autosomal recessive congenital cataract.

BACKGROUND: Congenital cataract is causing one-third of blindness worldwide. Congenital cataract is heterogeneous in its inheritance patterns. The current study is aimed to explore the unknown genetic causes underlying congenital cataracts. METHODS: Blood samples from affected and normal individuals of n = 25 Pakistani families identified with congenital cataracts were collected. Genomic DNA was extracted and Sanger sequencing was performed to identify novel pathogenic variants in the FYCO1 (MIM#607182) gene. Later structural bioinformatics tools and molecular dynamics simulations were performed to analyze the impact of these variants on protein structure and function. RESULTS: Sanger sequencing resulted in the identification of a novel splice site mutation (NM_024513.3: c.3151-29_3151-7del) segregating in an autosomal recessive manner. This novel variant was confirmed to be absent in the n = 300 population controls. Further, bioinformatics tools revealed the formation of a mutant protein with a loss of the Znf domain. In addition, we also found a previously known (c.4127 T > C; p.Leu1376Pro) mutation in four families. We also report a novel heterozygous variant (c.3419G > A; p.Arg1140Gln) in another family. CONCLUSIONS: In conclusion, we report a novel deletion (NM_024513.3: c.3151-29_3151-7del) in one family and a frequent homozygous missense mutation (c.4127 T > C; p.Leu1376Pro) in four Pakistani families. The current research highlights the importance of autophagy in lens development and maintaining its transparency.

XRCC1 and XPD DNA repair gene polymorphisms: a potential risk factor for glaucoma in the Pakistani population.

PURPOSE: The present study was designed to determine the association of polymorphisms of the DNA repair genes X-ray cross-complementing group 1 (XRCC1) (c.1316G>A [rs25487]) and xeroderma pigmentosum complementation group D (XPD) (c.2298A>C [rs13181]) with primary open-angle glaucoma (POAG) and primary closed-angle glaucoma (PCAG). METHODS: In this prospective case-control study, polymerase chain reaction-restriction fragment length polymorphism analysis was used to study the association of XRCC1 and XPD with 160 POAG patients, 163 PCAG patients, and 193 unaffected controls. RESULTS: XRCC1 rs25487 was found to be significantly associated specifically with male POAG patients (χ(2) = 13.2 [p = 0.001]), only for the dominant model (odds ratio [OR] = 2.65 [95% confidence interval [CI] = 1.44-4.85], p < 0.005). In addition XPD rs13181 was also found to be associated with male POAG patients (χ(2) = 12.1 [p < 0.005]), for both dominant (OR = 2.44 [95% CI = 1.33-4.47], p < 0.005) as well as recessive model (OR = 3.62 [95% CI = 1.45-9.01], p < 0.01). Combined genotypes of both the genes revealed that the heterozygote AC/GA was significantly associated with the male POAG patients (z = 3.00 [p < 0.001]). The AA/GG genotype was present at a higher frequency in the male controls and the AA/GA in the female controls and could thus have a protective role in males and females, respectively. CONCLUSIONS: We postulate that defects in the DNA repair genes XRCC1 and XPD may possibly be associated with the progression of POAG in male patients of Pakistani origin.

The association of glutathione S-transferase GSTT1 and GSTM1 gene polymorphism with pseudoexfoliative glaucoma in a Pakistani population.

PURPOSE: The aim of the present study was to investigate the association of glutathione S-transferase GSTT1 and GSTM1 genotypes with pseudoexfoliative glaucoma (PEXG) in a group of Pakistani patients. METHODS: Multiplex polymerase chain reaction was used to study the GSTT1 and GSTM1 polymorphisms in 165 PEXG patients and 162 unaffected controls. RESULTS: In the current study we describe a significant gender-specific association of GSTT1 and GSTM1 null genotypes with PEXG. The three null genotype combinations (i.e., T1M0, T0M1, and T0M0) were found at significantly higher frequencies in the PEXG patients as compared to the controls (χ(2)=21.82, p<0.001). This association was specifically related to the female patients (χ(2)=35.63, p<0.001); no such association was seen in the male patients (χ(2)=2.28, p>0.05). CONCLUSIONS: The results suggest that there is a significant involvement of the GSTT1 and GSTM1 polymorphisms in female Pakistani patients having PEXG, which suggests a possible gender-specific impairment of detoxification in this group.

Missense mutations at homologous positions in the fourth and fifth laminin A G-like domains of eyes shut homolog cause autosomal recessive retinitis pigmentosa.

PURPOSE: To describe two novel mutations in the eyes shut homolog (EYS) gene in two families with autosomal recessive retinitis pigmentosa (arRP) from Pakistan and Indonesia. METHODS: Genome-wide linkage and homozygosity mapping were performed using single nucleotide polymorphism microarray analysis in affected members of the two arRP families. Sequence analysis was performed to identify genetic changes in protein coding exons of EYS. RESULTS: In the Indonesian and Pakistani families, homozygous regions encompassing the EYS gene at 6q12 were identified, with maximum LOD scores of 1.8 and 3.6, respectively. Novel missense variants in the EYS gene (p.D2767Y and p.D3028Y) were found in the Pakistani and Indonesian families, respectively, that co-segregate with the disease phenotype. Interestingly, the missense variants are located at the same homologous position within the fourth and fifth laminin A G-like domains of EYS. CONCLUSIONS: To date, mostly protein-truncating mutations have been described in EYS, while only few patients have been described with pathogenic compound heterozygous missense mutations. The mutations p.D2767Y and p.D3028Y described in this study affect highly conserved residues at homologous positions in laminin A G-like domains and support the notion that missense mutations in EYS can cause arRP.

Association of eNOS and HSP70 gene polymorphisms with glaucoma in Pakistani cohorts.

PURPOSE: To investigate the involvement of stress-regulating genes, endothelial nitric oxide synthase (eNOS) and heat shock protein 70 (HSP70) with primary open angle glaucoma (POAG) and primary closed angle glaucoma (PCAG). METHODS: POAG and PCAG patients recruited from different areas of Pakistan were diagnosed on the basis of clinical history, raised intraocular pressure (IOP), cup-to-disc ratio (CDR) and visual field defects. Their blood was collected and genomic DNA was extracted from it, followed by PCR amplification and VNTR typing of the eNOS gene, while the HSP70 SNP was analyzed with PCR-RFLP. For both of the polymorphisms, the genotype distribution of the POAG and PCAG patients was compared with unaffected controls. RESULTS: HSP70 polymorphism was found to be significantly associated with PCAG (chi(2)=15.29 [p<0.001], OR=2.63 [95% CI=1.55-4.48]), with p<0.001 for the dominant model and OR=2.09 (95% CI=1.10-3.96) , with p<0.01 for the recessive model, but not with POAG (chi(2)=2.96 [p>0.05]). As opposed to this significant eNOS association, was seen with PCAG (chi(2)=6.33 [p<0.05], OR=2.09 [95% CI=1.12-3.89]), with p<0.01 for the dominant model, as well as with POAG (chi(2)=8.89 [p<0.05], OR=2.23 [95% CI=1.26-3.39]), with p<0.01 for dominant model. For the eNOS case, we found a significant association with the risk allele "a" for POAG patients (chi(2)=9.29 [p<0.01], OR=2.02 [95% CI=1.25-3.28, p=0.001]) and PCAG patients (chi(2)=7.59 [p<0.01], OR=1.99 [95% CI=1.18-3.37, p<0.01]). Similarly, in the HSP70 case, there was a significant association with the risk allele "C" for POAG patients (chi(2)=3.57 [p=0.05], OR=1.38 [95% CI=0.97-1.94, p<0.05]) and PCAG patients (chi(2)=18.32 (p<0.001), OR=2.16 [95% CI=1.49-3.13, p<0.001]). CONCLUSIONS: The intron 4 polymorphism of eNOS is associated with POAG, as well as PCAG, while the G+190C polymorphism in HSP70 is associated with PCAG, but not with POAG in the Pakistani population.

Novel mutations in the PITX2 gene in Pakistani and Mexican families with Axenfeld-Rieger syndrome.

PURPOSE: Axenfeld-Rieger syndrome (ARS) is a rare autosomal dominant disorder that affects the anterior segment of the eye. The aim of this study was to examine the PITX2 gene to identify possible novel mutations in Pakistani and Mexican families affected by the ARS phenotype. METHODS: Three unrelated probands with a diagnosis of ARS were recruited for this study. Genomic DNA was isolated from the peripheral blood of the probands and their family members. Polymerase chain reaction and Sanger sequencing were used for the analysis of coding exons and the flanking intronic regions of the PITX2 gene. Bioinformatics tools and database (VarSome, Provean, and MutationTaster, SIFT, PolyPhen-2, and HOPE) were evaluated to explore missense variants. RESULTS: We identified novel heterozygous variations in the PITX2 gene that segregated with the ARS phenotype within the families. The variant NM_153426.2(PITX2):c.226G > T or p.(Ala76Ser) and the mutation NM_153426.2(PITX2):c.455G > A or p.(Cys152Tyr) were identified in two Pakistani pedigrees, and the mutation NM_153426.2(PITX2):c.242_265del or p.(Lys81_Gln88del), segregated in a Mexican family. CONCLUSION: Our study extends the spectrum of PITX2 mutations in individuals with ARS, enabling an improved diagnosis of this rare but serious syndrome.

MTHFR gene C677T and A1298C polymorphisms and homocysteine levels in primary open angle and primary closed angle glaucoma.

PURPOSE: To investigate the methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C genotypes and plasma concentrations of total homocysteine (tHcy) in Pakistani patients with primary open angle glaucoma (POAG) and primary closed angle glaucoma (PCAG). METHODS: This was a prospective case-control study. A total of 295 patients (173 POAG, 122 PCAG) and 143 age- and sex-matched controls were subdivided into two ethnic groups, Punjabis (Punjab province, central Pakistan) and Pathans (North-West Frontier Province, northern Pakistan). Genotypes of the MTHFR C677T and A1298C polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). An enzyme-linked immunosorbent assay was used to determine the total serum homocysteine (tHcy) levels. Associations were determined by logistic regression analysis. RESULTS: Frequency distributions of genotypes and combined genotypes as well as homocysteine levels were obtained. The overall distribution of the C677T genotype was found to be significantly associated with PCAG (CC 69%, CT 21%, TT 10%; p=0.001, chi(2)=12.6), but not with POAG (CC 71%, CT 28%, TT 1%; p=0.98, chi(2)=0.02) as compared to the controls (CC 71%, CT 29%, TT 1%). The Pathan cohorts revealed no association with the disease; however, the Punjabis demonstrated a significant association with PCAG (CC 75%, CT 11%, TT 13%; p<0.001, chi(2)=17.2). PCAG in the Punjabi subjects was also significantly associated with the A1298C polymorphism (AA 43%, AC 54%, CC 3%; p<0.001, chi(2)=33.9) as compared to the controls. Combined genotype data showed no association with POAG; however, a significant association with all combined genotypes was observed in the overall PCAG subjects (p<0.05, chi(2)=20.1). This difference was particularly apparent in the TTAA and TTAC combinations that were completely absent in the control groups (p<0.05. chi(2)=49.6). Mean serum tHcy levels were found to be significantly increased in the POAG (15.2+/-1.28 micromol/l, p<0.001) and PCAG (20.8+/-4.8 micromol/l) groups as compared to the controls (10.0+/-0.97 micromol/l). The tHcy levels in the TT and AC genotype were significantly elevated in the PCAG group (67+/-12.39 micromol/l, p<0.001; 23+/-5.94 micromol/l, p=0.027) as compared to the controls. CONCLUSION: The TT and AC genotypes of MTHFR C677T and A1298C polymorphisms and the combined genotype TTAC were associated with PCAG in Punjabi subjects of Pakistani origin and correlated with the high serum tHcy levels seen in these patients.

Association of tumor necrosis factor alpha gene polymorphism G-308A with pseudoexfoliative glaucoma in the Pakistani population.

PURPOSE: The purpose of the present study was to determine the role of the tumor necrosis factor alpha (TNF-alpha) gene polymorphism G-308A and total serum immunoglobulin E (TsIgE) levels in the onset of pseudoexfoliation glaucoma (PEXG) in Pakistani patients. METHODS: The TNF-alpha polymorphism G-308A was analyzed in 122 patients with PEXG and 126 healthy unrelated controls by using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). TsIgE levels were determined by solid-phase enzyme-linked immunosorbent assay (ELISA). RESULTS: The AA and GA genotypes were strongly associated with PEXG (p<0.001), with an odds ratio (OR) of 0.07 (95% confidence interval [CI]=0.02-0.27) and 0.24 (95% CI=0.12-0.51), respectively, while the GG genotype was found at a higher frequency in controls as compared to patients (p<0.001) OR=8.95 (95% CI=4.55-17.81). No significant difference was found in TsIgE levels of both patients and controls (p=0.86). CONCLUSION: The present study concludes that the TNF-alpha polymorphism G-308A is strongly associated with PEXG. To our knowledge this is the first study in southeast Asia which demonstrates a strong association of a TNF-alpha polymorphism with PEXG.

MTHFR polymorphisms as risk for male infertility in Pakistan and its comparison with socioeconomic status in the world.

AIM: 5,10-MTHFR-single nucleotide polymorphisms are important for normal functioning of the enzyme that plays a key role in DNA synthesis, folate metabolism and methylation reactions. Methodology & results: Male infertility association of C665T and A1298C polymorphisms was explored, this topic is still debatable. Infertile men (232) and controls (114) were genotyped and statistically analyzed. Comparison of patients (6180) and controls (5744) of Caucasian populations was performed by meta-analysis. Pooled results showed A1298C minor allele and homozygous genotype to be of a significantly higher frequency in the low-income group. Increase in per capita income has shown an increasing trend in the minor allele frequency in various world populations, potentially due to dietry-folate compensation. CONCLUSION: A1298C seems more relevant marker than C665T for infertility association in Caucasian populations and may be addressed by improving dietary folate.

Identification of a Novel ZNF469 Mutation in a Pakistani Family With Brittle Cornea Syndrome.

PURPOSE: Brittle cornea syndrome (BCS) is a rare recessive disorder affecting connective tissues, most prominently in the eye. Pathogenic mutations causing BCS have been identified in PRDM5 and ZNF469 genes. This study investigates the genetic cause of BCS in a large, consanguineous Pakistani family with 4 affected and 3 unaffected individuals. METHODS: The coding region and exon-intron splice junctions of PRDM5 and ZNF469 genes were amplified by polymerase chain reaction, and bidirectional Sanger sequencing was performed to find the pathogenic change responsible for causing the disease in the family. RESULTS: A novel homozygous duplication c.9831dupC (p.Arg3278GlnfsX197) in the ZNF469 gene was identified, which was found to be co-segregating with the disease in the family. CONCLUSIONS: This is the first report of a ZNF469 homozygous mutation causing a BCS phenotype in a consanguineous Pakistani family. Our data extend the mutation spectrum of ZNF469 variants implicated in BCS.