A New Locus for Congenital Cataract, Microcornea, Microphthalmia, and Atypical Iris Coloboma Maps to Chromosome 2

A New Locus for Congenital Cataract, Microcornea, Microphthalmia, and Atypical Iris Coloboma Maps to Chromosome 2 Hana Abouzeid, MD,1 Françoise M. Meire, MD, PhD,2,3 Ihab Osman, MD,4 Nihal ElShakankiri, MD,4 Sylvain Bolay, Dipl Ing,5 Francis L. Munier, MD,1 Daniel F. Schorderet, MD5,6 Objective: To report a novel phenotype of autosomal dominant atypical congenital cataract associated with variable expression of microcornea, microphthalmia, and iris coloboma linked to chromosome 2. Molecular analysis of this phenotype may improve our understanding of anterior segment development. Design: Observational case study, genome linkage analysis, and gene mutation screening. Participants: Three families, 1 Egyptian and 2 Belgians, with a total of 31 affected were studied. Methods: Twenty-one affected subjects and 9 first-degree relatives underwent complete ophthalmic examination. In the Egyptian family, exclusion of PAX6, CRYAA, and MAF genes was demonstrated by haplotype analysis using microsatellite markers on chromosomes 11, 16, and 21. Genome-wide linkage analysis was then performed using 385 microsatellite markers on this family. In the 2 Belgian families, the PAX6 gene was screened for mutations by direct sequencing of all exons. Main Outcome Measures: Phenotype description, genome-wide linkage of the phenotype, linkage to the PAX6, CRYAA, and MAF genes, and mutation detection in the PAX6 gene. Results: Affected members of the 3 families had bilateral congenital cataracts inherited in an autosomal dominant pattern. A novel form of hexagonal nuclear cataract with cortical riders was expressed. Among affected subjects with available data, 95% had microcornea, 39% had microphthalmia, and 38% had iris coloboma. Seventy-five percent of the colobomata were atypical, showing a nasal superior location in 56%. A positive lod score of 4.86 was obtained at ␪ ⫽ 0 for D2S2309 on chromosome 2, a 4.9-Mb common haplotype flanked by D2S2309 and D2S2358 was obtained in the Egyptian family, and linkage to the PAX6, CRYAA, or MAF gene was excluded. In the 2 Belgian families, sequencing of the junctions and all coding exons of PAX6 did not reveal any molecular change. Conclusions: We describe a novel phenotype that includes the combination of a novel form of congenital hexagonal cataract, with variably expressed microcornea, microphthalmia, and atypical iris coloboma, not caused by PAX6 and mapping to chromosome 2. Financial Disclosure(s): The authors have no proprietary or commercial interest in any materials discussed in this article. Ophthalmology 2009;116:154 –162 © 2009 by the American Academy of Ophthalmology.

Cataract represents a leading cause of blindness worldwide, and the estimated incidence of congenital cataract is 2 to 3 per 10,000 live births.1–3 Most nonsyndromic congenital cataracts are inherited. The most common mode of transmission seems to be autosomal dominant, although autosomal recessive4 and X-linked patterns have been described.5,6 Hereditary cataracts show wide genetic and phenotypic heterogeneity.4,7,8 Studies of monogenic forms have led to the identification of at least 34 candidate loci, and to date more than 20 genes have been characterized.4 However, phenotype– genotype correlations are in a stage of relative infancy.4,6,9 Twin studies and sibling segregating studies respectively have shown that up to half of both nuclear10 and cortical11 age-related cataracts are heritable. It is reasonable to suspect that the genes responsible for congenital cataract may also influence age-related cataract and that ultimately studying

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© 2009 by the American Academy of Ophthalmology Published by Elsevier Inc.

these genes may help develop novel treatments for both groups. Despite significant breakthroughs in the understanding of the lens structure and development,12 the extended morphologic variations of lens opacities remain unclear.9 Congenital cataract may occur alongside other ocular anomalies, such as microcornea, coloboma, angle dysgenesis, and microphthalmia, the last being most frequent. Coloboma can involve any part of the eye. Failure of the anterior chorioretinal fissure to close characteristically leads to an inferonasal defect. The association of cataract and microcornea (Online Mendelian Inheritance in Man [OMIM] 116150) or cataract and microphthalmia (OMIM %156850, 610092) with and without iris coloboma have been described. The combination of such ocular anomalies suggests a disorder affecting eye development pathways. Genes such as PAX6, SOX2, and CHX10 were recently associated with ISSN 0161-6420/09/$–see front matter doi:10.1016/j.ophtha.2008.08.044

Abouzeid et al 䡠 A New Locus for Congenital Cataract major ocular malformations affecting both structure and size of the eye.13 Future studies of complex eye malformations are likely to characterize further human eye development pathways. We report an autosomal dominant syndrome in 3 families with differing ethnic backgrounds, with a novel form of hexagonal nuclear congenital cataract associated with variably expressed microcornea, microphthalmia, and atypical iris coloboma, not caused by PAX6 and mapping to chromosome 2. To our knowledge, this phenotype has not been reported. Functional, developmental, and genetic implications are discussed.

Materials and Methods Patients This study was approved by the Ethics Committee of the Faculty of Medicine of the University of Alexandria, Egypt, and was conducted in accordance to the tenets of the Declaration of Helsinki. Written informed consent was obtained from each study participant or a parent. We studied a 5-generation Egyptian family, Family A (Fig 1A), with a total of 25 affected subjects; 19 were alive and 6 were deceased but reported to be affected on clinical history. Sixteen affected members and 10 first-degree relatives were examined at the Department of Ophthalmology of the University of Alexandria, Egypt. Two additional Belgian families, Families B and C, of 2

generations each and a total of 6 affected subjects were included in the study (Fig 1B, C). All 4 children and the affected subjects’ parents of the 2 Belgian families were examined and underwent surgery at the Department of Ophthalmology, University Hospital of Ghent, Belgium. For all 3 families, a thorough clinical history was obtained from all family members or a parent, and they underwent, whenever possible, full physical and ocular examination, including Snellen visual acuity, gonioscopy, slit-lamp biomicroscopy, fundus examination, measurement of corneal diameter, and ultrasound measurement of axial length. Anterior segment and fundus photographs were obtained for all examined affected patients. Comprehensive physical examination results in all patients were normal. The history revealed that visible lens opacities were present from birth or very early in life in affected subjects. Of the 16 examined patients in Family A, 6 had previous cataract surgery at Alexandria University Hospital, 5 had previous surgery in a private eye clinic (thus preoperative data were missing), and 5 had no previous ocular surgery. Patient V-11 of Family A underwent operation elsewhere and refused to be examined, although he gave consent for blood drawing and analysis. Microcornea was defined as eyes with a horizontal corneal diameter less than 11.00 mm.14 Microphthalmia was set at less than 2 standard deviations below the age-adjusted mean and at less than 21.00 mm for patients aged more than 10 years.15

Molecular Analyses DNA from patients of the 3 families was extracted from peripheral leucocytes. In Family A, exclusion of PAX6, CRYAA, and MAF

Figure 1. Pedigrees. A, Pedigree and haplotypes of Family A, a 5-generation Egyptian family. Haplotype analysis identified a 4.9-Mb common interval on chromosome 2 flanked by D2S2309 and D2S2358. B, Family B: 2-generation Belgian family. C, Family C: second 2-generation Belgian family. Male (open squares) and female (open circles) unaffected subjects; male (solid squares) and female (solid circles) affected subjects; deceased (slash); examined (—).

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Ophthalmology Volume 116, Number 1, January 2009 Table 2. Summary of Ocular Assessment

Individual Family A IV-2 IV-4 IV-5 IV-7 V-3 V-4 V-5 V-6 V-7 V-10 V-14 V-16 V-17 V-18 V-19 Family B I-2 II-1 II-2 II-3 Family C I-2 II-1

Morphology of Cataract ODS

Age at Examination (y)

Age at Cataract Surgery (y)

Preoperative Best Corrected Snellen Visual Acuity Mean ODS

Postoperative Best Corrected Snellen Visual Acuity Mean ODS

52

Not operated

6/18

—

45 40 33

Not operated NA Not operated

6/60 NA 6/7.5

— 6/24 —

6 6 (mo) 9

6 6 (mo) 9

6/60 NA 6/60

6/24 NA 6/24

7

7

6/60

6/24

Not operated

6/60

—

11 19 13

NA NA 11

NA NA 6/60

6/24 6/18 6/24

11 20 18

10 NA Not operated

6/60 NA 6/10

6/24 6/20 —

40 17

NA 17

6/15 NA

6/10 6/15

14

14

6/60

6/60

14

14

6/30

6/20

45

45

6/120

6/30

13

13

6/100

6/20

RE: Nuclear, zonular, and anterior polar LE: Hexagonal nuclear Hexagonal nuclear NA, operated elsewhere RE: Superior cortical rider and zonular opacification Hexagonal nuclear Hexagonal nuclear Hexagonal nuclear, cortical riders, with posterior subcapsular opacity Hexagonal nuclear, cortical riders, with posterior subcapsular opacity Hexagonal nuclear with cortical riders and zonular NA, operated elsewhere NA, operated elsewhere Hexagonal nuclear, RE: with central defect of posterior lens capsule Hexagonal nuclear NA, operated elsewhere Posterior polar, with posterior subcapsular opacity Hexagonal nuclear Hexagonal nuclear with cortical riders and zonular Nuclear and zonular LE: and anterior polar Nuclear RE: Nuclear LE: Nuclear, zonular, and anterior polar Hexagonal nuclear and zonular

2

Y ⫽ yes; N ⫽ no; NA ⫽ not available; ODS ⫽ oculus dexter sinister (right left eye); RE ⫽ right eye; LE ⫽ left eye.

genes was performed by haplotype analysis using microsatellite markers on chromosomes 11, 16, and 21 (for markers, refer to Table 1, available at http://aaojournal.org). In Families B and C, direct sequencing of all exons of PAX6 was performed as previously described.16 In Family A, genome-wide scan was then performed with 385 fluorescently labeled microsatellite markers (ABI Prism Linkage Mapping Set MD10, panels 1–27, Applied Biosystems, Foster City, CA). Each multiplexed polymerase chain reaction (PCR) was carried out in a 5-␮L mixture containing 40 ng genomic DNA, various combinations of 10 ␮M fluorescent dye-labeled primer pairs, and MasterMix PCR solution. Amplification was carried out in various PCR machines. Initial denaturation was carried out for 10 minutes at 95°C, followed by 35 cycles of 30 seconds at 92°C, 55°C, and 72°C. A final extension cycle at 72°C for 10 minutes was performed. PCR products from each DNA sample were pooled and mixed with a loading cocktail containing formamide, Gs-400HD ROX standards (Applied Biosystems), and loading dye. The products were separated on an automatic sequence analyzer 3100XL (ABI XL3100, Applied Biosystems). Data were analyzed with ABI GeneScan 3.1 and GeneMapper version 4 (Applied Biosystems). Linkage analysis was performed using the Autoscan version of MLINK on a home-developed web interface, lodIRO (Bolay S, Bagnoud E, Puippe D, Seydoux J, Schorderet DF. LodIRO: Helping

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Linkage Based Eye Research Go Faster. Poster #1651/B318 presented at the ARVO Annual Meeting, May 7 2007; Fort Lauderdale), with a new mutation rate of 0.0001 and equal allele frequency.

Results Table 2 summarizes the clinical features of all affected patients in the 3 families.

Family A The proband of the Egyptian family (Fig 1A: V-5) presented with bilateral congenital cataracts, bilateral atypical iris coloboma of the superonasal quadrant (Fig 2A, B), bilateral microphthalmia, and microcornea. The novel cataract is illustrated in Figure 2C and D. The younger affected subject patient of this family, V-7 (Fig 1A), exhibited the same form of hexagonal cataract (Fig 3A, B). One affected subject adult who did not have surgery, IV-2 (Fig 1A), presented with a morphologically distinct lens opacity shown in Figure 3C. Two patients, IV-7 and V-19 (Fig 1A), presented with a milder form of cataract (Fig 4A, B). Only 2 subjects (V-4 and

Abouzeid et al 䡠 A New Locus for Congenital Cataract

Figure 2. The novel form of congenital cataract. A, Right eye (RE) miosis. Patient V-5 from Family A, at 9 years, with incomplete atypical superonasal iris coloboma, at 2:30 clock hour, with triangular shape, interrupting the border of the pupil. B, Left eye (LE) miosis. Same atypical iris coloboma at 10:30. C, RE mydriasis. Same patient harboring a novel form of congenital nuclear cataract characterized by opacification of the fetal nucleus with a hexagonal shape attributed to the prominence of the sutures edges, anteriorly and posteriorly delineated by the Y-sutures, and by cortical extension of the opacifications in the coronal plane, both laterally and in the prolongation of sutures axis. Opacities in the prolongation of sutures axis, so-called riders, and lateral extension were slightly asymmetric between the 2 eyes. A mild opacity of the posterior capsule was also observed. D, LE mydriasis. Note the cortical extension of the opacification, the so-called riders, in continuation of the 3 anterior nuclear sutures. E and F, RE and LE mydriasis. Patient II-1 from the Belgian Family B, at 17 years, with same phenotype as the previous case with prominent cortical riders similar to those of the previous patient’s LE. Irides were normal. RE ⫽ right eye; LE ⫽ left eye.

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Figure 3. Different manifestation of the cataract. A and B, RE and LE miosis. Patient V-7 from Family A, at 2 years of age, with double-shape nasal iris coloboma. The iris defect is both superior and inferior with an intact iris in between. Note the hexagonal-like shape of the cataract with limited zonular extension and the similarity between both eyes. C, Patient IV-2 from Family A, at 52 years of age. RE with nuclear cataract with additional zonular opacities and an anterior extension connecting the nuclear cataract to an anterior polar cataract, with an image of double plane cataract, the anterior one being smaller than the posterior, resembling the pyramidal type of cataract. D, Patient IV-2 from Family A, at 52 years of age, LE with hexagonal-like shape nuclear cataract caused by lateral extension of the sutural opacification, in the coronal plane. Note the asymmetry between the 2 eyes. E and F, RE and LE mydriasis. Patient I-2 from Family C, at 45 years of age, had a dense white nuclear cataract in both eyes. In her LE, the nuclear opacity was surrounded by an irregular zonular cataract and connected to an anterior polar cataract, similar to the one described in C. She presented an atypical nasal superior iris coloboma in her LE. Remnants of the prepupillary membrane were observed in both eyes. RE ⫽ right eye; LE ⫽ left eye.

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Abouzeid et al 䡠 A New Locus for Congenital Cataract

Figure 4. Cataract: low expression. A, Patient IV-7 from Family A, at 33 years of age, presented with a milder form of cataract consisting of a mild opacity in the upper temporal nucleus corresponding to a rider and with slight zonular opacification (partially visible on this picture). B, RE and LE. Patient V-19 from Family A, at 18 years of age, presented a moderate posterior polar cataract with asymmetric opacification of the posterior capsule between RE and LE. RE ⫽ right eye; LE ⫽ left eye.

V-17, Fig 1A) in this family presented with nystagmus. In this family, horizontal corneal diameters ranged from 8.5 to 11.0 mm.

Family B The second family included 4 affected subject patients of Belgian origin (Fig 1B). Patient I-2 had a dense fetal nuclear cataract with

an anterior polar opacity in the right eye. The cataract extended laterally in her left eye, and she had bilateral typical inferior iris coloboma. Patient II-1 (Fig 1B) presented with bilateral congenital cataract similar to the proband of Family A (Fig 2E, F). Anterior segments of patients II-2 and II-3 are presented in Figure 5. Only patient II-2 (Fig 1B) presented with nystagmus. In this family, horizontal corneal diameters ranged from 10.0 to 10.5 mm.

Figure 5. Spectrum of iris colobomata. A and B, RE and LE. Patient II-2 from Family B, at 15 years of age, with upper temporal atypical iris coloboma of the LE. A white nuclear cataract was observed in the LE, surrounded by a very irregular zonular cataract and connected to an anterior polar cataract. RE presented normal pupil with nuclear and anterior polar cataract. C and D, Patient II-3 from Family B, at 14 years of age, with bilateral inferior typical iris coloboma and nuclear cataract. RE ⫽ right eye; LE ⫽ left eye.

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Ophthalmology Volume 116, Number 1, January 2009 Table 3. Summary of the Clinical Spectrum of Affected Eyes Major Features

Family A

Family B

Family C

Total

%

Fetal nucleus opacity/total affected subjects’ eyes with available data Microcornea/total affected subjects’ eyes with available data Microphthalmia/total affected subjects’ with available data Iris coloboma/total affected subjects’ eyes with available data Atypical Nasal superior Temp superior Nasal and temp superior Typical (inferior) Nystagmus/total patients with available data

18/22 23/25 12/23 10/30 10/10 8/10 0/10 2/10 0/10 2/15

8/8 8/8 1/6 5/8 1/5 0/5 1/5 0/5 4/5 1/4

4/4 4/4 0/4 1/4 1/1 1/1 0/1 0/1 0/1 0/2

30/34 35/37 13/33 16/42 12/16 9/16 1/16 2/16 4/16 3/21

88 95 39 38 75 56 6 13 25 14

Family C In this Belgian family (Fig 1C), the 2 affected members, the mother and daughter, presented with the same congenital nuclear cataract expressed in Families A and B (Table 2, Fig 3E, F). The daughter, Patient II-1, had a nuclear cataract as described in Patient V-5 of Family A but with normal irides. Both the affected subjects had normal axial lengths that ranged from 21.26 to 23.09 mm. None of them had nystagmus. Horizontal corneal diameters ranged from 10.0 to 10.5 mm. In the 3 families, no surgical complications such as secondary glaucoma or keratopathy occurred. No further ocular or systemic malformations/diseases were observed in these 3 families, especially no choroidal or posterior segment colobomas and no glaucoma. Table 3 summarizes the number of patients presenting with each of the clinical features associated with cataract, namely, microcornea, microphthalmia, iris coloboma, and nystagmus. In the 2 Belgian families, sequencing of the junctions and all coding exons of PAX6 did not reveal any molecular change. Linkage analysis in Family A identified a region on chromosome 2 with a maximum lod score of 4.86 for marker D2S2309 at ␪ ⫽ 0 (Table 4). Two critical recombinant events occurred in patients V-7 and V-18/V-19. Patient V-7 recombined between D2S117 and D2S2309, thus setting the upper boundary of the linked interval. The lower boundary was determined by patients V-18 and V-19, in whom a recombination occurred between D2S325 and D2S2358. These recombinations identified a 4.9-Mb common interval flanked by D2S2309 and D2S2358 (Fig 1). One unaffected individual (V-13) shared the same 2 markers in the linked interval (Fig 1). This may be due to identity by state. Because V-11 is homozygous for both alleles, we have to assume

Table 4. Linkage Analysis of Congenital Cataract, Microcornea, Microphthalmia, and Atypical Iris Coloboma in Family A: Equal Allele Frequencies Were Used in the Calculation of Z (Lod Score) at Different Recombination Map Distances (Theta) from the Locus Markers on Chromosome 2 D2S364 D2S118 D2S117 D2S2309 D2S2358 D2S325 D2S2361

160

Theta 0.00

0.1

0.2

0.3

0.4

0.36 0.22 0.11 0.04 0.01 ⫺00 0.94 1.07 0.75 0.28 ⫺00 2.73 2.16 1.4 0.57 4.86 3.87 2.82 1.71 0.27 4.03 3.1 2.2 1.29 0.44 1.33 0.95 0.56 0.21 0.01 ⫺3.52 ⫺0.4 ⫺0.13 ⫺0.04 ⫺0.01

Zmax (Lod Score) 0.36 1.1 2.84 4.86 4.03 1.33 0

that his unaffected mother carried a nondisease-related 192–189 haplotype that she transmitted to her daughter V-13. We also excluded by linkage analysis the possibility that PAX6 on chromosome 11, MAF on chromosome 16, and CRYAA on chromosome 21 could be responsible for this phenotype in Family A (Table 1, available at http://aaojournal.org).

Discussion Dominantly inherited cataract associated with microcornea, atypical iris coloboma, and microphthalmia in these 3 families of different ethnic backgrounds constitutes a rare phenotype. We found no previous descriptions using a computerized Medline search. All affected subjects presented with congenital cataract associated with microcornea in 95% and with microphthalmia in only 39%, with variable severity (Tables 2 and 3). Iris coloboma was the least frequent feature (38%), predominantly presenting in the atypical form (75%) (Table 3). The novel cataract morphology segregated in the 3 families did not correspond to any previously published descriptions. This cataract has characteristic sutural and intersutural lenticular opacification (with or without cortical riders), giving rise to a hexagonal shape when suture opacifications join with predominant involvement of the nucleus. The cataract was pleomorphic and showed a wide range of morphologic variability, including fetal nuclear, zonular, polar, and subcapsular cataract with involvement of the fetal nucleus in the majority of cases (88%, Table 3). Intrafamilial variability of the phenotype was also observed to a large degree, adding to the complexity of the described syndrome. Within a single family and despite monogenic inheritance, phenotypic variability of cataract has been described, suggesting the influence of genetic or other modifiers.9 The visual effect of the cataract was relatively mild considering only 14% of affected patients had preoperative nystagmus, whether iris coloboma was present or not (Table 3). The overall postoperative results resulted in visual acuity improvement in the majority of patients, even when surgery was performed as late as 45 years of age. Duke-Elder17 classified iris coloboma as “typical” when it occurs inferiorly, in the position of the incompletely closed fetal fissure, and “atypical” when it occurs elsewhere, the latter being rare. An isolated case of a boy with a combination including aniridia, cataract, microcornea, and microphthalmia caused by a PAX6 mutation has been re-

Abouzeid et al 䡠 A New Locus for Congenital Cataract ported.18 This report suggests that the association we describe could arise from the same modifications of PAX6dependent developmental pathways. Nevertheless, linkage analysis excluded the possibility that PAX6 could be responsible for this phenotype in Family A, and sequencing of PAX6 did not reveal any disease-causing mutation in the 2 Belgian families B and C. In our families, the majority of iris colobomata were atypical, and notably there were no typical colobomata in Family A. This constitutes a rare phenotype with only 10 cases of atypical coloboma previously described.19 Nevertheless, incomplete aniridia was only considered a distinct entity years after the descriptions by Waardenburg.20 Therefore, earlier reports of atypical coloboma may contain incomplete forms of aniridia. The combination of dominantly inherited cataract and microphthalmia (OMIM %156850) has been reported in few pedigrees;21–24 in 2 of them, cataract, microphthalmia, and microcornea were observed in combination.21,22 Ferda Percin et al25 (OMIM 610092) observed 2 affected subjects from a consanguineous family who had recessively inherited bilateral microphthalmia, congenital cataracts, and bilateral inferior typical iris coloboma. In this family, single mutations of the CHX10 gene on chromosome 14q24, encoding a homeobox transcription factor, were identified, providing the first molecular basis for nonsyndromic iris coloboma. Beby et al24 recently reported congenital cataract, microphthalmia, and typical iris coloboma associated with a mutation in the CRYAA gene on chromosome 21. In none of the cited reports did the cataract phenotype match the hexagonal one or our families. The association of congenital cataract and microcornea, cataract-microcornea syndrome (CCMC, OMIM 116150), in the absence of other ocular anomalies has been described in a few families,26 –33 but with different cataract morphology than that found in our families. Cataract and microcornea have been associated with additional ocular anomalies, including typical iris coloboma.33–35 Indeed, mutations causing cataract, microcornea, and microphthalmia have been identified in the alpha,36 beta,37 and gamma D-crystallin genes,38 as well as in the GJA8 connexin gene.31,38 Pulverulent and posterior polar cataract associated with microcornea and typical iris coloboma, but without microphthalmia, has been linked to the MAF transcription factor gene,35,39 confirming genetic heterogeneity of typical iris coloboma, which is also related to CHX10 and CRYAA, as previously mentioned.24,25 Nevertheless, the region linked to the new syndrome we describe extends over 4.9 Mb on chromosome 2, which is clearly centromeric to the CRYGA-D cluster present at 2q34, and involvement of CRYGA-D and CHX10 was excluded by linkage analysis of Family A, as well as involvement of other potential loci, such as PAX6, MAF, and CRYAA. Molecular analysis of additional members from the Egyptian family is needed to refine the region. Families B and C were too small and did not help in refining the linked interval, nor could we firmly establish whether they mapped to the same chromosomal region. Nevertheless, the interval defined by D2S2309 and D2S2358 contains at least 33 genes, 13 LOC and 2 FLJ entities. On the basis of eye

expression and involvement in either eye development or lens structures, the following genes represent good candidates: neuropilin-2 precursor; bone morphogenetic protein receptor type II; cytochrome P450, family 20, subfamily A, polypeptide 1; or Caenorhabditis elegans Par-3 partitioning defective 3 homolog. Sequencing of all the exons and intron-exon junction is under way. We report a new locus of 4.9 Mb on chromosome 2q33 (D2S2309-D2S2358) for a novel hexagonal nuclear cataract associated with microcornea, variably expressed microphthalmia, and atypical iris coloboma. Transmission was autosomal dominant with complete penetrance and variable expressivity. The region described was centromeric of the crystallin cluster on chromosome 2. Molecular analysis of additional affected subjects is needed to further refine the region.

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Footnotes and Financial Disclosures Originally received: April 14, 2008. Final revision: July 2, 2008. Accepted: August 20, 2008. Available online: November 12, 2008.

5

Institute for Research in Ophthalmology, Sion, Switzerland. Ecole polytechnique fédérale de Lausanne, Lausanne, Switzerland. Financial Disclosure(s): The authors have no proprietary or commercial interest in any materials discussed in this article. Supported by grant 32–11194/1 from the Swiss National Science Foundation (Drs Munier and Schorderet). 6

Manuscript no. 2008-463.

1

Jules-Gonin Eye Hospital, University of Lausanne, Switzerland.

2

Department of Ophthalmology, University Hospital of Ghent, Belgium.

3

Department of Paediatric Ophthalmology, Hôpital Universitaire des Enfants Reine Fabiola, Brussels, Belgium. 4

Department of Ophthalmology, University of Alexandria, Egypt.

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Correspondence: Francis L. Munier, MD, Jules-Gonin Eye Hospital, 15 avenue de France CH-1004 Lausanne, Switzerland.

Abouzeid et al 䡠 A New Locus for Congenital Cataract Table 1. List and Chromosomal Positions of the Markers Used for Linkage to PAX6, CRYAA, and MAF Genes in Family A Marker PAX6 on Chromosome 11 D11S4046 D11S1338 D11S902 D11S904 D11S935 D11S905 D11S4191 D11S987 D11S1314 D11S937 D11S901 D11S4175 D11S898 D11S908 D11S925 D11S4151 D11S1320 D11S968 MAF on Chromosome 16 D16S423 D16S404 D16S3075 D16S3103 D16S3046 D16S3068 D16S3136 D16S415 D16S503 D16S515 D16S516 D16S3091 D16S520 CRYAA on Chromosome 21 D21S1911 D21S1256 D21S1914 D21S263 D21S1252 D21S266

Start Position Marshfield Zmax (bp) Map (Lod Score) 31’767’034 1’920’218.00 5’944’606.00 17’445’082.00 26’637’180.00 35’979’835.00 40’930’877.00 59’756’293.00 67’649’916.00 72’000’840.00 77’531’974.00 81’522’433.00 89’891’659.00 100’561’685.00 114’792’573.00 120’333’474.00 125’797’370.00 * 133’323’667.00 78’185’763 5’983’156 9’625’896 12’116’704 17’381’053 20’794’008 25’418’268 49’263’770 52’228’236 62’156’304 75’074’576 * 81’538’066 85’073’645 43’462’210 15’062’607 18’244’636 24’544’272 31’143’804 36’748’755 41’606’434

2.79 12.92 21.47 33.57 45.94 51.95 60.09 67.48 73.64 79.98 85.48 91.47 98.98 * 118.47 127.33 141.91 147.77

0.048 0.059 0.010 0.000 0.293 0.129 0.000 0.966 0.000 0.000 0.000 0.153 0.000 0.014 0.002 0.001 0.000 0.000

10.36 18.07 23.28 32.07 40.65 48.53 62.11 67.62 83.55 92.1 100.39 111.12 125.82

0.000 0.343 0.000 0.031 0.000 1.039 0.106 0.000 0.000 0.383 0.000 0.04 1.323

0.00 9.72 19.39 27.40 35.45 45.87

0 0.010 0.040 0.023 0.000 0.000

bp ⫽ base pair. *Not on the Marshfield or National Center for Biotechnology Information map.

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