[show abstract][hide abstract] ABSTRACT: Purpose: A combination of linkage mapping and gene association studies have been used to establish an association between SNP markers and a group of Afro-Caribbean POAG subjects from Barbados. The two highly associated SNPs of rs12994401 and rs1533428 are located within the AK127244 gene and map to the upper boundary of the POAG locus of GLC1H on 2p16. We aimed to reproduce this study in an unrelated group of British Caucasian POAG subjects, and further screen our previously linked POAG families for possible mutations in the AK127244 gene. Methods: A total of 692 Caucasian subjects (277 POAG, 71 LTG and 344 normal controls) were genotyped for 3 SNP markers on 2p16.3 region. An additional group of 34 African subjects were also genotyped for the same SNPs. Genotypic and allelic association studies were carried out by standard Chi-squared tests. Seven familial probands were also sequenced for the AK127244 gene using an ABI-3100 Gene Analyzer instrument. Results: No genetic association was identified for POAG, LTG or their combined group with 3 SNP markers of rs1533428 (Allelic p-values of 0.368, 0.715 and 0.378), rs11686436 (0.334, 0.511 and 0.298) or rs12994401 (0.447, 0.715 and 0.620), respectively. Likewise, haplotype association tests between each two set of SNP markers for the pooled group of glaucoma cases (POAG and LTG) was not statistically significant. Only the T&T haplotype permutation for the rs1533428/rs11686436 combination was marginally significant (p=0.013). However, this test proved to be insignificant after correction for multiple testing. Comparison of allelic frequencies in 34 African cases with the published data did not show any significance for the 3 SNP markers that we tested. Since these 3 SNP markers are located within the AK127244 gene, we further sequenced this gene in 7 familial probands from the GLC1H locus. Of the 41 SNP markers observed, 18 were non-coding and the remaining showed no mutations in the affected subjects. Conclusions: The reported genetic association of rs1533428 and rs12994401 in the Barbados cohort of Afro-Caribbean POAG cases could not be replicated in our group of 348 British Caucasian POAG and LTG subjects. Moreover, the AK127244 gene, which harbors these SNP markers, showed no mutations in our GLC1H-linked POAG families. In conclusion, the reported genetic association may either have a minute role in the non-African POAG populations or be limited to the Afro-Caribbean population of Barbados.
American Society of Human Genetics, Washington D.C., USA; 01/2010
[show abstract][hide abstract] ABSTRACT: Purpose:Single nucleotide polymorphisms (SNPs) in the LOXL1 gene have been implicated as the principal genetic risk factor for exfoliation syndrome (XFS). XFS is associated with sensorineural hearing loss (SNHL). We investigated whether LOXL1 genetic variations also confer risk factor for age-related SNHL.
Methods:We recruited 99 SNHL patients (54M, mean age 72.8 +/- 10.9; 45F, mean age 72.0 +/- 10.3), defined as hearing thresholds on pure-tone audiometry >25dB at any of the examined frequencies in one or both ears. LOXL1 gene polymorphisms (R141L and G153D) were genotyped in 276 subjects (84 cases and 192 controls) by direct sequencing. Association studies were carried out with SNP-STAT and PLINK programs.
Results:Case-control genotypic comparisons were not significant for R141L (p=0.080) and G153D (p=0.060). The corresponding allelic frequencies for cases and controls were 0.679 and 0.738 for R141L/G-allele (p=0.153; OR=1.34) and 0.857 and 0.780 for G153D/G-allele (p=0.036; OR=0.591), respectively. As the observed G153D/G-allele frequency was overrepresented in the cases, we further examined the combined haplotype effect of both R141L and G153D in these subjects. Marginally significant association was observed for underrepresented "GA" haplotype in cases (p=0.041; OR=0.60). Relative haplotype comparisons was only significant when underrepresented "GA" haplotype was compared with overrepresented "TG" haplotype (p=0.027; OR=1.88). In view of this observation, we are genotyping additional cases and further sequencing the entire LOXL1 coding exons in a group of SNHL subjects.
Conclusions:The association of LOXL1 gene polymorphisms with XFS may also be true for SNHL. Our marginally observed association between LOXL1 and SNHL requires further confirmation.
Association for Research in Vision and Ophthalmology, Fort Lauderdale, Florida, USA; 01/2009
[show abstract][hide abstract] ABSTRACT: Primary open angle glaucoma (POAG) is a hereditary optic neuropathy and a common cause of blindness worldwide. In part, POAG is caused by mutations in MYOC, OPTN and WDR36 genes. A recent genome wide study in the Icelandic population identified a significant association between exfoliation glaucoma and LOXL1 (Lysyl Oxidase-Like 1) gene polymorphisms. Herein, we investigated genetic contribution of 3 coding variants of LOXL1 in high-pressure POAG and normal-pressure glaucoma (NPG) subjects. All participating glaucoma and normal subjects were Caucasians and received a full ophthalmological examination. A total of 733 (156 POAG, 244 NPG and 333 normal) subjects were genotyped for 3 LOXL1 variants of R141L (rs1048661), G153D (rs3825942) and S159A. Genotypic and allelic frequencies were tabulated and statistical tests evaluated between normal and glaucoma subjects. The observed R141L allele (G;T) frequencies were: POAG (199;113), NPG (323;165) and controls (464;196). The G153D allele (G;A) frequencies were: POAG (266;46), NPG (413;75) and controls (530;134). The S159A allele (T;G) frequencies were: POAG (311;1), NPG (480;8) and controls (172;8). The S159A was generally uninformative. No significant associations were observed for any of the 3 LOXL1 coding variations. A marginal allelic (p=0.0363) but not genotypic association (p=0.0732) was observed for G153D in the NPG group. Likewise, when for R141L and G153D the 3 haplotype frequencies of GG, GA and TG (TA was not observed) were tabulated for POAG, NPG and control groups, no significant associations were detected. Our prior studies confirmed that there is a significant association between the LOXL1 gene polymorphisms for both exfoliation syndrome and exfoliation glaucoma (Mol Vis 2008; 14:533-541). However, present study suggests that no such association exist between LOXL1 variations with both high- and normal-pressure glaucoma. Supported by M01RR-06192.
American Society of Human Genetics, Philadelphia, Pennsylvania, USA; 11/2008
[show abstract][hide abstract] ABSTRACT: The objective of this study was to examine the biochemical and physical properties of cytochrome P450 1B1 (CYP1B1) mutants, test our hypothesis that primary congenital glaucoma (PCG)-causing mutants have altered metabolic activity, and correlate these to structural changes in the molecule.
CYP1B1.1 cDNA was mutated to four forms found in individuals with the PCG phenotype, Y81N, E229K, A330F, and R368H. Expression and stability of the mutant hemoproteins and their ability to metabolize beta-estradiol, arachidonic acid, and retinoids, were determined. Alterations in mutant properties were related to structural changes by in silico examination, on the basis of the CYP1A2 crystal structure.
CYP1B1 mutations strongly affected the stability, ease of heterologous expression, and enzymatic properties of the protein. These were related to the location of the amino acid substitutions in the CYP1B1 structure. Three of the mutations involve residues located on the surface of CYP1B1, Y81N, and E229K near the distal surface, and R368H near the proximal surface. The former two substitutions, Y81N and E229K, caused greatly reduced stability at 4 degrees C. Y81N severely inhibited all substrate turnover, but E229K only inhibited arachidonate turnover and exhibited minimal effect on efficiency of retinoid metabolism and estradiol metabolism. The R368H mutation is relatively conservative, affecting charge-pairing with the deeper-located D374, but it severely inhibited metabolism of all substrates tested, and, like Y81N, expression of the enzyme is less facile than CYP1B1wt. The A330F mutation replaces a small alanine by a bulky phenylalanine in the enzyme active site and had major impact on substrate binding, turnover, uncoupling, and metabolite pattern.
Consistent with the hypothesis, these PCG-related mutations cause identifiable structural changes negatively impacting CYP1B1 biochemistry and stability.
Pharmacogenetics and Genomics 09/2008; 18(8):665-76. · 3.61 Impact Factor
[show abstract][hide abstract] ABSTRACT: Primary lymphoedema is a genetic disorder with numerous phenotypic subgroups. The most common form is the non-syndromic Meige disease, which is primarily of pubertal or later onset, with oedema clinically indistinguishable from that found in the lymphoedema-distichiasis syndrome. There are also other very rare forms of lymphoedema such as yellow nail syndrome and lymphoedema with ptosis, which are clinically similar to Meige disease. The only causative genes so far identified for the non-congenital primary lymphoedemas are the transcription factor FOXC2, where mutations are known to produce lymphoedema with distichiasis, and SOX18 in the very rare condition hypotrichosis-lymphoedema-telangiectasia. This study has examined FOXC2 gene by sequence analysis in 23 affected individuals with Meige disease. A novel truncating mutation (c.563-584del) was identified in one family and found to segregate with the disease in eight affected relatives over three generations. This deletion creates a frameshift that predicts a premature stop at nucleotide 599 and truncating the normal protein by 38%. Although the affected patient initially selected for mutation screening from this family had lymphoedema without distichiasis, all but one of his affected relatives who carried the FOXC2 mutation did have accessory eyelashes originating from their meibomian glands. This is further confirmation that of the primary lymphoedemas, only lymphoedema with distichiasis is caused by FOXC2 mutations. All forms of post-pubertal lymphoedema need careful phenotyping for distichiasis, which may prove difficult to confirm unless several family members are examined, and cannot ever be assumed to be absent from self-report.
European Journal of HumanGenetics 04/2008; 16(3):300-4. · 4.32 Impact Factor
[show abstract][hide abstract] ABSTRACT: To evaluate genetic susceptibility of lysyl oxidase-like 1 (LOXL1) gene polymorphisms to exfoliation syndrome (XFS) and exfoliation glaucoma (XFG) in a case-control cohort of American and European patients.
DNA from a total of 620 individuals including 287 exfoliation patients and 333 healthy control subjects were extracted by standard methods. Three single nucleotide polymorphisms (SNPs) of rs1048661 (R141L), rs3825942 (G153D), and rs2165241 were genotyped in these individuals by SNaPshot Assay. The seven coding exons of the LOXL1 gene and their immediate flanking regions were directly sequenced in 95 affected patients. Data management and case-control association studies were performed with SNP-STAT and PLINK programs. The obtained DNA sequences were evaluated with the STADEN package.
The 287 unrelated exfoliation cases comprised of 171 American patients (mostly of European background) and 116 patients from 12 European countries. This phenotype was further divided into patients with exfoliation only and no glaucoma (XFO; n=95), exfoliation with glaucoma (XFG; n=133), and exfoliation unclassified (XFU; n=59). Genotypic data were analyzed separately for XFO, XFG, XFU, and XFS (all exfoliations; n=287) and for Americans and Europeans. The observed genotypic frequencies for each exfoliation phenotype or population were tabulated separately and tested for deviation from the Hardy-Weinberg equilibrium (HWE) using a standard Chi(2) test. There were no HWE deviations and no significant genotypic differences between these subcategories for the three studied SNPs. For the combined exfoliation cohort, homozygote genotypes of G/G (rs1048661), G/G (rs3825942), and T/T (rs2165241) were significantly overrepresented. Likewise, case-control allelic association for rs1048661 (p=7.74x10(-9)), rs3825942 (p=3.10x10(-17)), and rs2165241 (p=4.85x10(-24)) were highly significant. The corresponding two-locus haplotype frequencies of GG for rs1048661-rs3825942 (p=1.47x10(-27)), GT for rs1048661-rs2165241 (p=1.29x10(-24)), and GT for rs3825942-rs2165241 (p=2.02x10(-24)) were highly associated with exfoliation phenotypes. The combined effect of these three SNPs revealed that the GGT haplotype is overrepresented by 66% in exfoliation cases, and this deviation from controls is highly significant (p=1.93x10(-24)). This haplotype constituted a major risk factor for development of exfoliation in both XFS and XFG. By contrast, the GAC haplotype was significantly underrepresented (p=4.99x10(-18)) in exfoliation cases by 83% and may potentially have a protective effect for this condition with an estimated attributable risk percent reduction of 457%. The only other haplotype that was significantly different between cases and controls was TGC (p=5.82x10(-9)). No observation was made for the GAT haplotype. The combined three haplotypes of GGT, GAC, and TGC were associated with 91% of the exfoliation syndrome cases in the studied populations. Seven coding exons of LOXL1 were also sequenced in 95 affected cases. In addition to the three above-mentioned SNPs, 12 other variations were also observed in these patients (G240G, D292D, A320A, V385V, rs2304719, IVS3+23C>T, IVS3-155G>A, IVS3-101G>A, IVS4+49G>A, rs2304721, IVS5-121C>T, and rs2304722). None were considered a disease-causing mutation.
We confirmed a strong association with LOXL1 variants in our patients. For the LOXL1 gene, individual alleles of rs1048661 (G), rs3825942 (G), and rs2165241 (T) are highly associated with XFS and XFG in American and European populations. The GGT haplotype constitutes a major risk haplotype for exfoliation, and GAC may have a protective role. DNA sequencing of 95 affected patients did not show any mutations in this gene. The LOXL1 SNPs are located in the 15q24.1 band and within a genetic locus (GLC1N) that is associated with primary open-angle glaucoma (POAG). However, the LOXL1 genetic predisposition is only limited to exfoliation with or without glaucoma and does not include the POAG phenotype.
[show abstract][hide abstract] ABSTRACT: The molecular defect of one large consanguineous Iranian kindred with Leber Congenital Amaurosis (LCA) is presented. The phenotype mapped to 17p13.1 (LCA1) and excluded from five other LCA loci. Sequence analysis of the GUCY2D gene identified a novel homozygous missense mutation (I816S) that segregated with the inherited disease-haplotype in six affected, eight parents, and two normal gene carriers. This mutation was absent in three other normal family members and 92 normal control subjects. In silico analysis predicted that alteration of the highly conserved isoleucine residue at position 816 to serine is deleterious by affecting secondary structure of the GUCY2D protein.
[show abstract][hide abstract] ABSTRACT: Purpose:Genetic susceptibility of exfoliation glaucoma (XFG) and exfoliation syndrome (XFS) to the LOXL1 gene variants has recently been reported. We tested 275 affected subjects and 287 matched controls for these variants.
Methods:Single Nucleotide Polymorphisms (SNPs) of rs1048661 (R141L), rs3825942 (G153D) and rs2165241 were genotyped in 562 individuals by SNaPshot Assay. The LOXL1 gene was also sequenced in 95 affected subjects. Case-control association studies were analyzed with SNP-STAT and PLINK programs. DNA sequences were evaluated with STADEN package.
Results:The 275 exfoliation cases (89 XFG) comprised of 171 American (mostly European background) and 104 subjects from 12 European countries. Genotypic data were analyzed separately for XFS, XFG and for Americans and Europeans. There were no significant differences between these categories for any SNPs. For the exfoliation cohort, homozygote genotypes of G/G (rs1048661), G/G (rs3825942) and T/T (rs2165241) were over-represented. Case-control allelic association for rs1048661 (p=7.19x10-14), rs3825942 (p=2.61x10-13) and rs2165241 (p=3.05x10-24) were highly significant. Two-locus haplotype frequencies of G-G for rs1048661-rs3825942 (p=1.54x10-24), G-T for rs1048661-rs2165241 (p=1.21x10-30) and G-T for rs3825942-rs2165241 (p= 1.67x10-28) were also significant. Affected cases showed a significantly higher allelic frequency of G-G-T and this specific arrangement constituted a major risk haplotype for both XFS and XFG. Seven coding exons of LOXL1 were also sequenced in 95 affected cases. In addition to the 3 above-mentioned SNPs, we also observed V373D, V385V, rs2304719, rs2304721, rs2304722, IVS3+23C>T and IVS5-64T>C in these patients. None was considered a mutation. Genotyping of these SNPs in additional exfoliation and control subjects and further evaluation of genetic association are still in progress.
Conclusions:We confirmed a strong association with LOXL1 variants in our patients. The G alleles of rs1048661 and rs3825942 together with the T allele of rs2165241 are highly associated with XFS and XFG. The combination of G-G-T constituted a major risk haplotype for exfoliation. DNA sequencing of 95 affected subjects did not show any mutations in the LOXL1 gene.
Association for Research in Vision and Ophthalmology, Fort Lauderdale, Florida, USA; 01/2008
[show abstract][hide abstract] ABSTRACT: We show, for the first time, the spatiotemporal appearance of Cyp1b1 protein during mouse eye ontogeny. The protein was unambiguously identified in the adult mouse eye and newborn (P0) whole mouse microsomes and was shown to be localized in inner ciliary epithelium, corneal epithelium, retinal inner nuclear cells, and ganglion cells. The enzyme protein was present in the lens epithelium adjacent to the developing ciliary body at 15.5 days postconception (E15.5) and was most strongly expressed during E17.5 to 7 days postnatally (P07). Subsequently, it declined to very low levels. The protein was also expressed in the corneal endothelial cells adjacent to the ciliary body at P07. Cyp1b1 was barely detectable in the inner ciliary epithelium before E17.5 but increased rapidly postnatally, reaching adult levels by P28. Levels of the enzyme protein in the corneal epithelium were seen from E15.5 onward, increasing sharply, and after a decrease at P07, were highest in the adult animal eye. The presence of Cyp1b1 protein in the inner nuclear layer of the retina was very low in the prenatal eye, increasing rapidly postnatally, and was highest in the adult animal eye. In the ganglion cell layer of the retina, it increased slowly from E15.5 to P07 and then rapidly reached adult levels. Interestingly, Cyp1b1 was not detected in the trabecular meshwork at any stage of development or in the adult eye. We conclude that the enzyme may play important roles in normal eye development and function in mice as in humans, and that the mouse may prove to be an excellent model for determination of the roles of CYP1B1 in human eye development and function.
Drug Metabolism and Disposition 07/2007; 35(6):987-94. · 3.36 Impact Factor
[show abstract][hide abstract] ABSTRACT: To analyze optineurin (Optn) gene expression in various embryonic stages of mouse development by whole mount in situ hybridization.
FVB/NcrlBR mouse embryos (10.5 and 13.5 dpc) were collected by timed breeding experiments. A 712 bp Optn cDNA fragment was amplified by PCR and cloned into a transcription vector pCRII-TOPO. Digoxigenin labeled sense and antisense RNA probes were generated by in vitro transcription. The labeled RNA probe was localized using an anti-digoxigenin antibody conjugated with alkaline phosphatase. Colorimetric detection was performed with substrate solution containing, 4-nitro-blue tetrazolium chloride (NBT) and 5-bromo-4-chloro-3-indolyl phosphate (BCIP).
This study revealed that the developing eye represents a major expression site for Optn. At both 10.5 and 13.5 dpc a strong specific expression was detected in the outer layer of the optic cup (future pigment layer of the retina). This is in contrast to the expression of another glaucoma gene, Cyp1b1, the expression of which at this state is only limited to the inner (neural) layer of the optic cup (future nervous layer of the retina). Inspection of sections from the cephalic region of whole mounts also revealed limited Optn staining in the lens as well as in the optic nerve. A second Optn expression domain was detected at the base of the developing forelimb. The biological significance of this observation is not clear and remains to be determined.
Eye and forelimb were identified as two major sites for expression of the Optn gene. These findings suggest that Optn expression is triggered during early stages of eye development. Expression of the Optn gene in ocular tissues during mouse embryogenesis correlates with the presence and distribution of the optineurin protein, as previously reported in adult ocular tissues. These findings are also in agreement with the predicted function of Optn protein in the eye and the role of its ortholog in human glaucoma. Further investigations are required to determine the molecular mechanisms of Optn in the developing murine forelimb.
[show abstract][hide abstract] ABSTRACT: To map new genetic loci for adult-onset primary open-angle glaucoma (POAG) by using families previously unlinked to GLC1A-GLC1F.
Initial genome scan and subsequent saturation mapping confirmed linkage to a locus on chromosome 2p15-p16. Forty-nine DNA samples from a single family with POAG with 113 individuals were used in this study. The 10 affected members of this family had an average age at onset of 64 years, moderate to high intraocular pressure, glaucomatous visual field loss, and cup-disc ratios of 0.6 to 0.9.
Haplotype construction in 9 available affected subjects established a single inherited chromosome from D2S123 to D2S2165, within an 11-megabase (Mb) region. Further analysis revealed no recombination with 8 consecutive DNA markers (D2S1364-D2S2332) and provided a maximum logarithm of the odds (LOD) score of 2.97 for D2S370. Six additional families also showed consistent linkage and 1 affected recombination may further confine this locus to an 8.3-Mb region (D2S2352-D2S2165). Combined analysis of 7 families provided a maximum LOD score of 9.30 with D2S2320.
A new genetic locus (GLC1H) for adult-onset POAG maps to the 2p15-p16 region.
Mapping of the GLC1H locus and eventual identification of its defective gene will help to develop diagnostic tools and effective treatments for this condition.
Archives of Ophthalmology 02/2007; 125(1):86-92. · 3.83 Impact Factor
[show abstract][hide abstract] ABSTRACT: Glaucoma is a blinding condition that affects millions of people worldwide. Of the 20 loci published so far, only 4 of their defective genes (CYP1B1, MYOC, OPTN, WDR36) have been identified. In this study, we used published information on Linkage Mapping, mRNA expression, Microarray Data, known Biological Function or Predicted Biochemical Pathways of candidate proteins and prioritized a selected group of genes for specific screening at the GLC1B (2cen-q13), GLC1C (3q23) and GLC1H (2p16) loci. The GLC1B region contains over 220 genes, of which we previously excluded 20 of them. Bioinformatic, Genomic Convergence and Proteomic Streamlining methods prioritized 23 of these genes as the most promising candidates. We screened and excluded 7 new genes (TGOLN2, MAT2A, ST3GAL5, BCL2L11, NCK2, UNC50, FHL2) from this region. Only 3 non-synonymous, non-disease causing variations were observed in TGOLN2 (R259W, F453L) and FHL2 (R88K). Likewise, we screened 10 genes (ACPL2, ZBTB38, RASA2, RNF7, GRK7, ATP1B3, TFDP2, GK5, XRN1 and ATR) from the GLC1C locus and identified a total of 90 DNA variations. Seven non-disease causing alterations were observed in ZBTB38 (P300A, S319A, N617D), GRK7 (E443G, P460T) and ATR (M211T, R2606Q). For the GLC1H locus, we previously screened and excluded 29 genes. In this study, a total of 10 new genes were prioritized from a list of over 61 possible candidates. Six of these genes (RPS27A, EFEMP1, USP34, PSME4, PAPLOG and RTN4) were screened and excluded. Altogether, 72 genes were screened from these 3 published POAG regions. Screening of other prioritized genes is currently in progress. The overall linkage data suggest that GLC1B, GLC1C, and GLC1H loci are physically located within regions of 6.66, 1.32 and 10.90 Mb, respectively. The strategy used in this study will facilitate gene selection for detailed mutation screening at these 3 known POAG-linked loci. Supported by EY-009947 and M01RR-06192.
American Society of Human Genetics, San Diego, California, USA; 01/2007
[show abstract][hide abstract] ABSTRACT: To determine whether there is a correlation among mutations in the cytochrome P4501B1 gene (CYP1B1), the degree of angle dysgenesis observed histologically, and disease severity in congenital glaucoma.
Interventional case series.
Direct DNA sequencing was used to screen six unrelated children with congenital glaucoma, each set of parents, and all siblings for CYP1B1 mutations. Specimens of the anterior chamber angle obtained at trabeculectomy were examined histologically to identify abnormalities of the aqueous outflow pathway. CYP1B1 mutations were correlated with both the degree of angle dysgenesis and the patients' disease severity (age at diagnosis, difficulty in achieving intraocular pressure [IOP]) control.
Four (66.7%) of the six patients were compound heterozygotes for mutations in the CYP1B1 gene. Seven of the eight CYP1B1 mutations were identified, including two novel mutations (R117P, C209R) and five others previously described (G61E, R368H, R390H, E229K, 4340delG). The cases were divided on the basis of histological phenotype into categories of (1) severe goniodysgenesis highlighted by the agenesis of the canal of Schlemm (two patients), (2) moderate goniodysgenesis characterized by the presence of a band of collagenous tissue (CT) in the trabecular meshwork (TM) and/or the juxtacanalicular tissues (JXT) (three patients), and (3) mild goniodysgenesis with deposition of a mucopolysaccharide material in the JXT (one patient). CYP1B1 mutations were identified in both cases of severe angle dysgenesis and two of three cases of moderate dysgenesis. Disease severity closely correlated with the degree of angle dysgenesis.
Most patients in our cohort had compound heterozygous CYP1B1 mutations. Specific CYP1B1 mutations may be associated with severe or moderate angle abnormalities.
American Journal of Ophthalmology 01/2007; 142(6):993-1004. · 3.63 Impact Factor
[show abstract][hide abstract] ABSTRACT: Dup(3q) syndrome is a congenital developmental disorder resulting from a duplication of the distal portion of the long arm of chromosome 3. Symptoms typically include craniofacial abnormalities like cleft palate and craniosynotosis, clinodactyly and other mild upper limb and digital anomalies, delayed skeletal maturation, and mild mental retardation. However, one well characterized patient had an unbalanced 3;22 translocation leading to a chromosomal duplication from 3q25.3 to 3qter. Surprisingly, this patient had a more severe phenotype with microbrachycephaly, high arched palate, micrognathia, and profound mental retardation. FISH analysis using BACs from the chromosome 3q25–3q27 region revealed that the patient had a microdeletion within the region of 3q duplication. FISH analysis using subclones of the BACs within the region confirmed and narrowed the microdeletion to the boundary of 3q26-q27. Quantitative analysis of copy number by primer extension at specific SNP locations (SNuPE) within the region revealed that the microdeletion involved only the TRAF2 and NCK-interacting Kinase (TNIK) locus on chromosome 3q26-q27. The microdeletion generated an imbalance in copy number between TNIK (2 copies) and the remaining chromosome 3q25.3-qter region (3 copies). This microdeletion was not present in Dup(3q) syndrome patients with the milder phenotype. Our conclusion is that duplication of TNIK normally modulates the effect of duplication of other genes within the Dup(3q) syndrome region and that an imbalance in copy number between TNIK and the rest of chromosome 3q leads to a more severe Dup(3q) syndrome phenotype.
Disclosures: J.D. Akunowicz, None.
Journal of Bone and Mineral Research 01/2007; 22(Supplement S1):s302–s351. · 6.13 Impact Factor
[show abstract][hide abstract] ABSTRACT: To determine whether mutations in the WD40-repeat 36 (WDR36) gene are responsible for primary open-angle glaucoma (POAG) that maps to the GLC1G locus in a family with 16 affected family members.
Ninety-two family members underwent clinical evaluation for POAG on the basis of intraocular pressures, cupping of discs, and visual fields after informed consent was obtained. All 23 exons of WDR36 were sequenced in DNA from 5 affected and 2 unaffected family members.
Sixteen family members showed evidence of POAG. A number of sequence variations were identified in family members; most of the variations were previously described single-nucleotide polymorphisms also present in the general population. The 3 new sequence changes were all intronic; 2 were found in only 1 of the family members undergoing screening.
Several polymorphisms, including known single-nucleotide polymorphisms, were identified; however, none of these were consistent with disease-causing mutations. A mutation in a noncoding region of WDR36 may be responsible for POAG in this family, or another gene in this region may be the actual cause of glaucoma in this family.
The finding that the WDR36 gene is probably not the responsible gene in this family further documents the genetic heterogeneity of POAG.
Archives of Ophthalmology 10/2006; 124(9):1328-31. · 3.83 Impact Factor
[show abstract][hide abstract] ABSTRACT: To determine whether there is a correlation among mutations in the cytochrome P450 1B1 gene (CYP1B1), the degree of angle dysgenesis observed histologically, and disease severity in congenital glaucoma.
Direct DNA sequencing was utilized to screen six unrelated children with congenital glaucoma, each set of parents, and all siblings for CYP1B1 mutations. Specimens of the anterior chamber angle obtained at trabeculectomy were examined histologically to identify abnormalities of the aqueous outflow pathway. CYP1B1 mutations were correlated with both the degree of angle dysgenesis and the patient's disease severity (age at diagnosis, difficulty in achieving intraocular pressure control).
Four of the six patients (66.7%) were compound heterozygotes for mutations in the CYP1B1 gene. Seven of the eight CYP1B1 mutations were identified, including two novel mutations (R117P, C209R) and five others previously described (G61E, R368H, R390H, E229K, 4340delG). The cases were divided based on histological phenotype into categories of (1) severe goniodysgenesis highlighted by the agenesis of Schlemm's canal (two patients), (2) moderate goniodysgenesis characterized by the presence of a band of collagenous tissue in the trabecular meshwork and/or the juxtacanalicular tissues (three patients), and (3) mild goniodysgenesis with deposition of a mucopolysaccharide material in the juxtacanalicular tissue (one patient). CYP1B1 mutations were identified in both cases of severe angle dysgenesis and two of three cases of moderate dysgenesis. Disease severity closely correlated with the degree of angle dysgenesis.
The majority of cases in the cohort had compound heterozygous CYP1B1 mutations. Specific CYP1B1 mutations may be associated with severe or moderate angle abnormalities.
Transactions of the American Ophthalmological Society 02/2006; 104:183-95.
[show abstract][hide abstract] ABSTRACT: Expression of 10 CYP orthologs (Families 1-3) in developing mouse conceptus is constitutive. These forms have specific temporal and spatial expression. Studies on CYP1B1 indicate its requirement for normal eye development, both in human and mouse. The distribution of the enzyme in the mouse eye is in three regions, which may reflect three different, perhaps equally important, functions in this organ. Its presence in the inner ciliary and lens epithelia appears to be necessary for normal development of the trabecular meshwork and its function in regulating intraocular pressure. Its expression in the retinal ganglion and inner nuclear layers may reflect a role in maintenance of the visual cycle. Its expression in the corneal epithelium may indicate a function in metabolism of environmental xenobiotics.
Drug Metabolism Reviews 02/2006; 38(1-2):337-52. · 5.54 Impact Factor