Molecular Vision 2005; 11:971-976 <>
Received 21 June 2005 | Accepted 29 October 2005 | Published 9 November 2005

A new congenital nuclear cataract caused by a missense mutation in the γD-crystallin gene (CRYGD) in a Chinese family

Jingzhi Gu,1 Yanhua Qi,1 Li Wang,1 Jin Wang,1 Lisong Shi,2 Hui Lin,1 Xiang Li,1 Hong Su,1 Shangzhi Huang2

1Department of Ophthalmology, the Second Affiliated Hospital of Harbin Medicine University, Harbin, China; 2Department of Medical Genetics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Peking, China

Correspondence to: Jingzhi Gu, Affiliated Second Hospital of Harbin Medicine, University Heilongjiang Province, 246 Baojian Road, Harbin 150086, China; Phone: 0086-0451-86605851; FAX: 0086-0451-86605116; email:


Purpose: To identify genetic defects associated with nuclear golden crystal autosomal dominant congenital cataract (ADCC) in a Chinese pedigree in the north of China.

Methods: Clinical data were collected and the phenotype of the affected members in this family was recorded by slit lamp photography. Genomic DNA was isolated from peripheral blood. Linkage analyses excluded all known loci except that in 2q33-q35. Mutation analysis of CRYGs was carried by direct sequencing of the PCR products.

Results: Sequencing of the coding regions of CRYGA, CRYGB, CRYGC, and CRYGD showed the presence of a heterozygous C>A transversion at nt109 of the coding sequence (R36S) in exon 2 of CRYGD, which co-segregated with the affected members.

Conclusions: The R36S mutation in CRYGD identified in this Chinese family caused a nuclear golden crystal cataract phenotype not described before. This finding is an additional indication that there may be phenotypic heterogeneity of cataract, especially in different races.


Congenital cataracts are a significant cause of visual impairment in childhood. They have a high incidence and are a significant cause of vision loss world wide causing approximately one tenth of childhood blindness [1]. Roughly 50% of congenital cataracts are hereditary and family studies have revealed that approximately 30% of children with bilateral isolated congenital cataract had a genetic basis [2].

Congenital cataract is phenotypically and genetically heterogeneous. To date, congenital cataracts, isolated or syndromic forms, have been mapped to 27 genetic loci, and the disease-associated mutations have been identified in 18 genes, including those coding for αA-crystallin [3,4], αB-crystallin [5], βA1-crystallin [6,7], βB1-crystallin [8], βB2-crystallin [9], γC-crystallin [10], γD-crystallin [11-13], beaded filament structural protein 2 [14], heat shock transcription factor 4 [15], gap junction protein alpha-3 [16], gap junction protein alpha-8 [17], paired-like homeodomain transcription factor-3 [18,19], ferritin [20], galactokinase 1 [21], glucosaminyl(N-acetyl)transferase 2 [22], major intrinsic protein of lens fiber (MIP) [23], lens intrinsic membrane protein 2 (LIM2) [24], and paired box gene 6 [25]. Among them, 12 distinct genes have been identified to cause nonsyndromic autosomal dominant cataracts, including seven genes coding for crystallin (CRYAA, CRYAB, CRYBA1/A3, CRYBB1, CRYBB2, CRYGC, CRYGD) and two genes coding for gap junctional channel protein (GJA3, GJA8), one gene coding for heat-shock transcription factor 4 gene (HSF4), one gene coding for major intrinsic protein (MIP), and one gene coding for beaded filament structural protein 2 (BFSP2). Also, a mutation in CRYGS with autosomal dominant cataract in humans was recently reported [26].

In our study, we performed linkage analysis on a four generation Chinese family with nuclear golden crystal cataracts by using STRs markers on 12 ADCC loci and haplotype analysis with makers on 2q33-q35. A missense mutation in exon 2 of the CRYGD gene was identified, which is responsible for the disease in this pedigree.


Clinical evaluation

The family was ascertained by the Department of Ophthalmology, the Second Affiliated Hospital of Harbin Medicine University, Heilongjiang province, China. Informed consent in accordance with the Declaration of Helsinki and the Heilongjiang Institutional Review Board approval was obtained from all participants. The pedigree was a four generation family with 7 members affected (Figure 1). ADCC diagnosis was established by the presence of affected individuals in each generation and male to male transmission. Affected status was determined by the surgical records of cataract extraction for the patients or ophthalmologic examination, included slit lamp examination with dilated pupils, visual acuity testing, intraocular pressure measurement, fundus examination, and ultrasonic examination. Peripheral blood (5 ml) was collected from each of 5 available affected and 5 unaffected individuals in the family, and genomic DNA was extracted using standard protocol.

Genotyping and linkage analysis

Twenty-one microsatellite markers close linked to 12 known ADCC loci were used to perform allele-sharing among patients in the family, including D1S252, D1S305, D2S1782, D2S325, D3S1290, D3S1744, D11S898, D11S1986, D12S90, D12S1676, D13S1236, D13S175, D16S3034, D16S421, D17S1294, D17S1288, D21S212, D22S1174, D22S315, TOP1P2, CRYBB2 and three additional markers, D2S2318, D2S1384, and D2S1385, linked to the CRYGs. The oligonucleotide primer sequences were selected from The GDB Human Genome Database. The order and genetic distances of the markers were derived from the Marshfield database. Microsatellites were amplified by polymerase chain reaction (PCR) following standard methods. The genotypes were obtained by silver stain and manual inspection. The pedigree and haplotype was constructed by Cyrillic version 2.1 (MathStat Software ;Victoria, Australia).

Mutation analysis

DNA samples from all available affected and unaffected family members of the family were screened for mutations in CRYGA, CRYGB, CRYGC, and CRYGD by direct cycle sequencing of the PCR products. The genomic sequence of CRYGs was obtained from the Ensemble genome data resources. Gene specific PCR primers were used to amplify the three exons and flanking introns sequences of CRYGA, CRYGB (sequences available upon request), CRYGC, and CRYGD (Table 1). PCR products were sequenced in both directions, and the data were collected and analyzed using ABI 3730XL sequencer (Perkin-Elmer, Applied Biosystems, Foster City, CA).


Clinical findings

All affected members showed nuclear cataract, presented at birth or developed during infancy, progressing slowly with age. One of them has had cataract extraction. In the other four patients without cataract extraction, the cataract was bilateral and consisted of a central pulverulent opacity affecting the embryonal, fetal, and infantile nucleus of the lens, characterized by golden crystal punctuate, with metal-like refractivity in the opaque nucleus (Figure 2, Figure 3). From the hospital records, the best corrected visual acuity of the affected eyes varied from 20/200 to 40/200 before cataract extraction. There was no family history of any other ocular or systemic abnormalities. Autosomal dominant inheritance of the phenotype was supported by the presence of affected individuals in each of the four generations and with a male to male transmission.

Mutation detection

Allele-sharing analysis among the affected members in the family excluded linkage with the 11 ADCC loci other than those on 2q33-35. Haplotype analysis on chromosome 2q33-35 showed that a block of 5 markers (black bar in Figure 1) was co-segregated with the disease in this family. Direct sequencing was performed to cover exons and flanking intron-exon boundary sequences. A heterozygous C>A transversion (Figure 4, Figure 5) was identified at nucleotide 109 in exon 2 of CRYGD in all affected members, but was not observed in any of the unaffected family members. Fifty unrelated control individuals were also sequenced and the possibility of a rare polymorphism was excluded.


In this report, after excluding all known loci corresponding to ADCC in a Chinese family except on 2q33-35, we have identified a locus on 2q33.3-q34 associated with the nuclear golden crystal cataract and found that a C>A transversion in exon 2 of CRYGD in all affected members of the family. This mutation co-segregated with the cataract in the family and no mutation was identified in the 100 independent control allele.

It is known that only CRYGC and CRYGD encode abundant lens γ-crystallins in humans [27,28] and almost 90% of the γ-crystallins synthesized in human lens are the products of these two genes [29]. CRYGD is one of only two γ-crystallins to be expressed at high concentrations in the fiber cells of the human embryonic lens and these cells subsequently form the lens nucleus fibers. Many identified mutations in CRYGD have been and have proven to be cataractogenic. We think that the heterozygous mutation was responsible for the congenital cataract in this family. This is because first, Kmoch et al. [30] has identified this mutation in a Czech 5-year-old boy who suffered from photophobia and decreased visual acuity due to symmetrical crystal deposition and grayish opacities in both lenses, and then proved that cataract was caused by deposition of defined crystallized protein, γD crystallin. Second, we sequenced 100 alleles of 50 unrelated control individuals and exclude the possibility of a rare polymorphism. Third, the single transversion in the heterozygous state (cDNA 109C>A) predicted a R37S substitution at the protein level. The arginine residue is highly conserved, scoring 35 among 36 CRYGD homologs cloned from various species using the MAXHOM alignment [30]. This is the first report that the R36S caused autosomal dominant congenital cataract in China.

How does R36S mutation cause crystals in the lens nucleus and affect lens transparency? Kmoch et al. [30] analyzed this problem by protein crystallography and found that the crystal structure at 2.25 Å suggested that the R36S mutation in γ-crystallin has an unaltered protein fold and it was thought that the absence of the Arg36 charge led to the redistribution of the surface charges in the mutants which could decrease steric hindrances, promoting the permanent mutual contacts and aggregations of the protein molecules and decrease the solubility of the R36S mutated protein, leading to crystal formation. However, congenital cataract is phenotypically and genetically heterogeneous. The same mutation in cataract genes may result in different phenotypes under different ethic background and environment, even the same mutation can cause different cataractous phenotypes in a family, such as the Mexican pedigree with congenital hereditary cataract reported by Zenteno [31]. In contrast to the Czech boy's crystals [30], characterized by deposition of numerous birefringent, pleiochroic, and macroscopically prismatic crystals in the nucleus and cortex, our cases had many crystal dots in the lens with golden metal-like refractivity in the grey-white opaque nucleus. The punctuate crystal and pulverulent opacity affected the embryonal, fetal, and infantile nucleus of the lens, but the cortex was transparent. This, perhaps, is a phenotypic polymorphism of congenital cataract. It may indicate that gene expression or the formation of the protein structure for cataract might be influenced by many other factors, which include unidentified modifier genes and other sequence variations. Further studies will help us to better understand the mechanism of cataract formation and processing of gene expression.


We are grateful to the members of the family for their participation in this study. We also acknowledge the financial support of the Natural Scientific Fund of Heilongjiang Provincial Scientific and Technical Bureau (Grant D0218).


1. Gilbert CE, Canovas R, Hagan M, Rao S, Foster A. Causes of childhood blindness: results from west Africa, south India and Chile. Eye 1993; 7:184-8.

2. Rahi JS, Dezateaux C, British Congenital Cataract Interest Group. Measuring and interpreting the incidence of congenital ocular anomalies: lessons from a national study of congenital cataract in the UK. Invest Ophthalmol Vis Sci 2001; 42:1444-8.

3. Mackay DS, Andley UP, Shiels A. Cell death triggered by a novel mutation in the alphaA-crystallin gene underlies autosomal dominant cataract linked to chromosome 21q. Eur J Hum Genet 2003; 11:784-93.

4. Litt M, Kramer P, LaMorticella DM, Murphey W, Lovrien EW, Weleber RG. Autosomal dominant congenital cataract associated with a missense mutation in the human alpha crystallin gene CRYAA. Hum Mol Genet 1998; 7:471-4.

5. Berry V, Francis P, Reddy MA, Collyer D, Vithana E, MacKay I, Dawson G, Carey AH, Moore A, Bhattacharya SS, Quinlan RA. Alpha-B crystallin gene (CRYAB) mutation causes dominant congenital posterior polar cataract in humans. Am J Hum Genet 2001; 69:1141-5.

6. Qi Y, Jia H, Huang S, Lin H, Gu J, Su H, Zhang T, Gao Y, Qu L, Li D, Li Y. A deletion mutation in the betaA1/A3 crystallin gene (CRYBA1/A3) is associated with autosomal dominant congenital nuclear cataract in a Chinese family. Hum Genet 2004; 114:192-7.

7. Reddy MA, Bateman OA, Chakarova C, Ferris J, Berry V, Lomas E, Sarra R, Smith MA, Moore AT, Bhattacharya SS, Slingsby C. Characterization of the G91del CRYBA1/3-crystallin protein: a cause of human inherited cataract. Hum Mol Genet 2004; 13:945-53.

8. Mackay DS, Boskovska OB, Knopf HL, Lampi KJ, Shiels A. A nonsense mutation in CRYBB1 associated with autosomal dominant cataract linked to human chromosome 22q. Am J Hum Genet 2002; 71:1216-21.

9. Vanita, Sarhadi V, Reis A, Jung M, Singh D, Sperling K, Singh JR, Burger J. A unique form of autosomal dominant cataract explained by gene conversion between beta-crystallin B2 and its pseudogene. J Med Genet 2001; 38:392-6.

10. Heon E, Priston M, Schorderet DF, Billingsley GD, Girard PO, Lubsen N, Munier FL. The gamma-crystallins and human cataracts: a puzzle made clearer. Am J Hum Genet 1999; 65:1261-7.

11. Stephan DA, Gillanders E, Vanderveen D, Freas-Lutz D, Wistow G, Baxevanis AD, Robbins CM, VanAuken A, Quesenberry MI, Bailey-Wilson J, Juo SH, Trent JM, Smith L, Brownstein MJ. Progressive juvenile-onset punctate cataracts caused by mutation of the gammaD-crystallin gene. Proc Natl Acad Sci U S A 1999; 96:1008-12.

12. Nandrot E, Slingsby C, Basak A, Cherif-Chefchaouni M, Benazzouz B, Hajaji Y, Boutayeb S, Gribouval O, Arbogast L, Berraho A, Abitbol M, Hilal L. Gamma-D crystallin gene (CRYGD) mutation causes autosomal dominant congenital cerulean cataracts. J Med Genet 2003; 40:262-7.

13. Shentu X, Yao K, Xu W, Zheng S, Hu S, Gong X. Special fasciculiform cataract caused by a mutation in the gammaD-crystallin gene. Mol Vis 2004; 10:233-9 <>.

14. Conley YP, Erturk D, Keverline A, Mah TS, Keravala A, Barnes LR, Bruchis A, Hess JF, FitzGerald PG, Weeks DE, Ferrell RE, Gorin MB. A juvenile-onset, progressive cataract locus on chromosome 3q21-q22 is associated with a missense mutation in the beaded filament structural protein-2. Am J Hum Genet 2000; 66:1426-31.

15. Bu L, Jin Y, Shi Y, Chu R, Ban A, Eiberg H, Andres L, Jiang H, Zheng G, Qian M, Cui B, Xia Y, Liu J, Hu L, Zhao G, Hayden MR, Kong X. Mutant DNA-binding domain of HSF4 is associated with autosomal dominant lamellar and Marner cataract. Nat Genet 2002; 31:276-8.

16. Mackay D, Ionides A, Kibar Z, Rouleau G, Berry V, Moore A, Shiels A, Bhattacharya S. Connexin46 mutations in autosomal dominant congenital cataract. Am J Hum Genet 1999; 64:1357-64.

17. Berry V, Mackay D, Khaliq S, Francis PJ, Hameed A, Anwar K, Mehdi SQ, Newbold RJ, Ionides A, Shiels A, Moore T, Bhattacharya SS. Connexin 50 mutation in a family with congenital "zonular nuclear" pulverulent cataract of Pakistani origin. Hum Genet 1999; 105:168-70.

18. Willoughby CE, Arab S, Gandhi R, Zeinali S, Arab S, Luk D, Billingsley G, Munier FL, Heon E. A novel GJA8 mutation in an Iranian family with progressive autosomal dominant congenital nuclear cataract. J Med Genet 2003; 40:e124.

19. Semina EV, Ferrell RE, Mintz-Hittner HA, Bitoun P, Alward WL, Reiter RS, Funkhauser C, Daack-Hirsch S, Murray JC. A novel homeobox gene PITX3 is mutated in families with autosomal-dominant cataracts and ASMD. Nat Genet 1998; 19:167-70.

20. Aguilar-Martinez P, Biron C, Masmejean C, Jeanjean P, Schved JF. A novel mutation in the iron responsive element of ferritin L-subunit gene as a cause for hereditary hyperferritinemia-cataract syndrome. Blood 1996; 88:1895.

21. Stambolian D, Ai Y, Sidjanin D, Nesburn K, Sathe G, Rosenberg M, Bergsma DJ. Cloning of the galactokinase cDNA and identification of mutations in two families with cataracts. Nat Genet 1995; 10:307-12.

22. Yu LC, Twu YC, Chang CY, Lin M. Molecular basis of the adult i phenotype and the gene responsible for the expression of the human blood group I antigen. Blood 2001; 98:3840-5.

23. Berry V, Francis P, Kaushal S, Moore A, Bhattacharya S. Missense mutations in MIP underlie autosomal dominant 'polymorphic' and lamellar cataracts linked to 12q. Nat Genet 2000; 25:15-7.

24. Pras E, Levy-Nissenbaum E, Bakhan T, Lahat H, Assia E, Geffen-Carmi N, Frydman M, Goldman B, Pras E. A missense mutation in the LIM2 gene is associated with autosomal recessive presenile cataract in an inbred Iraqi Jewish family. Am J Hum Genet 2002; 70:1363-7.

25. Azuma N, Yamaguchi Y, Handa H, Hayakawa M, Kanai A, Yamada M. Missense mutation in the alternative splice region of the PAX6 gene in eye anomalies. Am J Hum Genet 1999; 65:656-63.

26. Sun H, Ma Z, Li Y, Liu B, Li Z, Ding X, Gao Y, Ma W, Tang X, Li X, Shen Y. Gamma-S crystallin gene (CRYGS) mutation causes dominant progressive cortical cataract in humans. J Med Genet 2005; 42:706-10.

27. Russell P, Meakin SO, Hohman TC, Tsui LC, Breitman ML. Relationship between proteins encoded by three human gamma-crystallin genes and distinct polypeptides in the eye lens. Mol Cell Biol 1987; 7:3320-3.

28. Brakenhoff RH, Aarts HJ, Reek FH, Lubsen NH, Schoenmakers JG. Human gamma-crystallin genes. A gene family on its way to extinction. J Mol Biol 1990; 216:519-32.

29. Siezen RJ, Thomson JA, Kaplan ED, Benedek GB. Human lens gamma-crystallins: isolation, identification, and characterization of the expressed gene products. Proc Natl Acad Sci U S A 1987; 84:6088-92.

30. Kmoch S, Brynda J, Asfaw B, Bezouska K, Novak P, Rezacova P, Ondrova L, Filipec M, Sedlacek J, Elleder M. Link between a novel human gammaD-crystallin allele and a unique cataract phenotype explained by protein crystallography. Hum Mol Genet 2000; 9:1779-86.

31. Zenteno JC, Morales ME, Moran-Barroso V, Sanchez-Navarro A. CRYGD gene analysis in a family with autosomal dominant congenital cataract: evidence for molecular homogeneity and intrafamilial clinical heterogeneity in aculeiform cataract. Mol Vis 2005; 11:438-42 <>.

Gu, Mol Vis 2005; 11:971-976 <>
©2005 Molecular Vision <>
ISSN 1090-0535