Reference
Complete the bibliographic reference for the article according to AJE format.

Stone E, et al. Missense Variations in the Fibulin 5 Gene and Age-Related Macular Degeneration. New Engl J Med 2004; 351:346-53.

Category of HuGE information
Specify the types of information (from the list below) available in the article:

1. Prevalence of gene variant
2. Gene-disease association
3. Gene-environment interaction
4. Gene-gene interaction
5. Genetic test evaluation/monitoring

2. Gene-disease association

Study hypotheses or purpose
The authors study hypotheses or main purpose for conducting the study

Gene(s)
Identification of the following:

1. Gene name
2. Chromosome location
3. Gene product/function
4. Alleles
5. OMIM #
6. GDPInfo link

1. Gene name: Fibulin 1(FBLN1)
2. Chromosome location: 22q13.3
3. Gene product/function: An extracellular matrix protein, which requires calcium-binding to mediate binding to laminin and nidogen. (1)
4. Alleles: No allelic variants were noted in OMIM. Fourteen sequence variants were found in this study.
5. OMIM #: *135820
6. Go to GDPInfo Genes A-Z result

1. Gene name: Fibulin 2 (FBLN2)
2. Chromosome location: 3p25-p24
3. Gene product/function: An isoform of FBLN1. (2)
4. Alleles: No allelic variants were noted in OMIM. Twenty-one sequence variants were found in this study.
5. OMIM #: *135821
6. Go to GDPInfo Genes A-Z result

1. Gene name: Fibulin 4 (FBLN4)
2. Chromosome location: 11q13
3. Gene product/function: An extracellular protein with several EGF-like domains. This gene shows significant homology to FBLN3, which is not being genotyped in this study. (3)
4. Alleles: No allelic variants were noted in OMIM. Four sequence variants were found in this study.
5. OMIM #: *604663
6. Go to GDPInfo Genes A-Z result

1. Gene name: Fibulin 5 (FBLN5)
2. Chromosome location: 14q32.1
3. Gene product/function: An EGF-like calcium-binding protein that promotes adhesion of endothelial cells, and may play a role in vascular development and remodeling. (4)
4. Alleles: At least nine amino-acid level variants have been found in the fibulin 5 gene. Seven of these variants were found in the current study.
5. OMIM #: *604580
6. Go to GDPInfo Genes A-Z result

1. Gene name: Fibulin 6 (FBLN6)
2. Chromosome location: 1q24-q25
3. Gene product/function: Hemicentin, an extracellular matrix protein. (5)
4. Alleles: One allelic variant was noted in OMIM, and it was previously associated with AMD. Fourteen sequence variants were found in this study.
5. OMIM #: *608548
6. Go to GDPInfo Genes A-Z result

None studied

Health outcome(s)
Identification of the major health outcome(s) studied

Age-related macular degeneration (AMD), the leading cause of irreversible vision loss in developed countries.

1. Case-control
2. Cohort 
3. Cross-sectional
4. Descriptive or case series
5. Clinical trial
6. Population screening

1. Disease case definition
2. Exclusion criteria
3. Gender
4. Race/ethnicity
5. Age
6. Time period
7. Geographic location
8. Number of participants

1. Disease case definition: Cases of age-related macular degeneration were defined as those that had one of the following features: drusen, disruption or atrophy of the retinal pigment epithelium, or choroidal neovascularization. The diagnosis of AMD for each patient was made by a trained retina specialist from either the University of Iowa Retina Clinic or another retina specialist from elsewhere in the United States.
2. Exclusion criteria: no exclusion criteria were specified.
3. Gender: not specified
4. Race/ethnicity: not specified
5. Age: not specified
6. Time period: not specified
7. Geographic location: majority from the University of Iowa (about 90%)
8. Number of participants: 402 (% of total eligible not reported)

1. Control selection criteria
2. Matching variables
3. Exclusion criteria
4. Gender
5. Race/ethnicity
6. Age
7. Time period
8. Geographic location
9. Number of participants

1. “General population” Control selection criteria: University of Iowa patients with no previous history of macular degeneration. This group did not have an eye exam to confirm.
2. Matching variables: none
3. Exclusion criteria:
4. Gender: not specified
5. Race/ethnicity: >80% Caucasian (the correct proportion was not stated in the paper- one of the major shortcomings of the study)
6. Age: > 50
7. Time period: not specified
8. Geographic location: Iowa
9. Number of participants: 263 (% of total eligible not specified)

1. “Other” Control selection criteria: University of Iowa patients
2. Matching variables: none
3. Exclusion criteria: family history of macular degeneration; evidence of macular degeneration on eye exam
4. Gender: not specified
5. Race/ethnicity: >80% Caucasian
6. Age: > 50 (mean 75.5 years)
7. Time period: not specified
8. Geographic location: Iowa
9. Number of participants: 166 (% of total eligible not specified)

Cohort definition
For study designs 2, 3, and 6, define the following if available:

1. Cohort selection criteria
2. Exclusion criteria
3. Gender
4. Race/ethnicity
5. Age
6. Time period
7. Geographic location
8. Number of participants (% of total eligible)

1. Cohort selection criteria: Not applicable.
2. Exclusion criteria:
3. Gender:
4. Race/ethnicity: [if not specified, insert ‘not specified']
5. Age:
6. Time period:
7. Geographic location: [if not specified, insert ‘not specified']
8. Number of participants: N (% of total eligible)

1. Environmental factor
2. Exposure assessment
3. Exposure definition
4. Number of participants with exposure data (% of total eligible)

1. Environmental factor: Not applicable
2. Exposure assessment:
3. Exposure definition:
4. Number of participants with exposure data: N (% of total eligible)

1. Gene
2. DNA source
3. Methodology
4. Number of participants genotyped (% of total eligible) 

1. Gene: Fibulin 1 (FBLN1)
2. DNA source: peripheral blood cells
3. Methodology: The entire coding sequence (minus one exon that would not amplify) of FBLN1 was screened for variations using a denaturing high-performance liquid chromatography assay. The evolutionary conservation of residues with sequence variations were evaluated using nucleotide BLAST and published expressed sequence tags .
4. Number of participants genotyped: all cases and general-population controls (N=665) were genotyped

1. Gene: Fibulin 2 (FBLN2)
2. DNA source: peripheral blood cells
3. Methodology: The entire coding sequence (minus one exon that would not amplify) of FBLN2 was screened for variations using a denaturing high-performance liquid chromatography assay. The evolutionary conservation of residues with sequence variations were evaluated using nucleotide BLAST and published expressed sequence tags.
4. Number of participants genotyped: all cases and general-population controls (N=665) were genotyped

1. Gene: Fibulin 4 (FBLN4)
2. DNA source: peripheral blood cells
3. Methodology: The entire coding sequence of FBLN4 was screened for variations using a denaturing high-performance liquid chromatography assay. The evolutionary conservation of residues with sequence variations were evaluated using nucleotide BLAST and published expressed sequence tags.
4. Number of participants genotyped: all cases and general-population controls (N=665) were genotyped

1. Gene: Fibulin 5 (FBLN5)
2. DNA source: peripheral blood cells; neurosensory retina, retinal pigment epithelium
3. Methodology: The entire coding sequence of FBLN5 was screened for variations using a denaturing high-performance liquid chromatography assay. The evolutionary conservation of residues with sequence variations were evaluated using nucleotide BLAST and published expressed sequence tags.
4. Number of participants genotyped: All cases and controls from both groups (N=831) were genotyped.

1. Gene: Fibulin 6 (FBLN6)
2. DNA source: peripheral blood cells
3. Methodology: The coding sequence (25 exons) of FBLN6 was screened for variations using a denaturing high-performance liquid chromatography assay. The evolutionary conservation of residues with sequence variations were evaluated using nucleotide BLAST and published expressed sequence tags.
4. Number of participants genotyped: all cases and general- population controls (N=665) were genotyped

Analysis
Comment on the analysis carried out by the author(s), e.g. matching, modeling or statistical tests used. Were the analyses appropriate?

1. Prevalence of gene variant
2. Gene-disease association
3. Gene-environment interaction
4. Gene-gene interaction
5. Genetic test evaluation/monitoring

1. Gene-disease association: Variations in fibulin 5 occur more frequently in cases than in controls. Variations in fibulin 6 also occur more frequently in cases than controls, but according to Fisher's exact test, there is no significant association. Only fibulin 5 showed a significant association between amino acid variations and AMD (P<0.01 by Fisher's exact test). Fibulin 2 and fibulin 6 each had a very common amino acid change that was present in equal frequency among patients and controls.

The authors found a significant association between sequence variations in the fibulin 5 gene and the typical form of age-related macular degeneration.

1. Despite the relatively large number of cases examined, only 1.7% of cases had fibulin 5 amino acid variants, which thus could account for only a small proportion of AMD cases.
   
   
2. There is the possibility of selection bias with the controls. Both groups of controls came from the University of Iowa, but it was unclear as to how they were located and recruited into this study. It is also not known why the controls were being seen in a retina clinic and could have other conditions related to AMD which could confound the association.
   
   
3. There is also the possibility of selection bias among the cases. The majority (N=367) were from the retina clinic at the University of Iowa, while the remaining 35 were “patients of retina specialists elsewhere in the United States.” It is unclear what proportion of FBLN5 variants were found in the Iowa group versus the group not from Iowa.
   
   
4. This study is not population-based; therefore, any gene-disease association that might be inferred from its results cannot be applied to the population as a whole.
   
   
5. Overall, the results of this study may help to focus future research on AMD pathology and etiology. While these extracellular matrix proteins may not be a large part of the cause of AMD, they may play a role in the underlying pathology and severity of the disease. More work is needed to understand the leading cause of irreversible vision loss in the developed world.

1. Online Mendelian Inheritance in Man, OMIM (TM). Johns Hopkins University, Baltimore, MD. MIM Number: 135820: 2/22/2005: World Wide Web URL: http://www.ncbi.nlm.nih.gov/omim/.
2. Online Mendelian Inheritance in Man, OMIM (TM). Johns Hopkins University, Baltimore, MD. MIM Number: 135821: 2/22/2005: World Wide Web URL: http://www.ncbi.nlm.nih.gov/omim/.
3. Online Mendelian Inheritance in Man, OMIM (TM). Johns Hopkins University, Baltimore, MD. MIM Number: 604663: 2/22/2005: World Wide Web URL: http://www.ncbi.nlm.nih.gov/omim/.
4. Online Mendelian Inheritance in Man, OMIM (TM). Johns Hopkins University, Baltimore, MD. MIM Number: 604580: 2/22/2005: World Wide Web URL: http://www.ncbi.nlm.nih.gov/omim/.
5. Online Mendelian Inheritance in Man, OMIM (TM). Johns Hopkins University, Baltimore, MD. MIM Number: 608548: 2/22/2005: World Wide Web URL: http://www.ncbi.nlm.nih.gov/omim/.