You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
myopia   is a highly prevalent eye disease and significant public health problem involving genetic and environmental factors .  
pathological myopia , generally named also high myopia , is defined as a refractive error of at least 6.00 diopters ( d ) with pathological changes , such as temperal crescent , pigment epithelium thinning , leopard retina , fuch 's macula , retina - choroidal atrophy , and so on .
pathological myopia affects approximately 2.84.6% of the adult population in australia , the united states , and western europe , and 0.95% in china .
10 affirmative gene loci had been known in nonsyndromic pm , including xq28(myp1 ) , 18p11.31(myp2 ) , 12q21-q23(myp3 ) , 7q36(myp4 ) , 17q21-q22 ( myp5 ) , 4q22-q27 , 2q37.1 , xq23-q25 , 15q12 - 13 , and 5p15.33-p15.2 [ 312 ] , although no gene has been confirmed finally among them .
the development of pm involves anterior - posterior enlargement of the eye , scleral thinning , and frequent detachment of the retina resulting from stress associated with excessive axial elongation . as a connective tissue ,
the sclera provides the structural framework that defines the shape and axial length of the eye .   in myp3 ,
lumican and decorin genes are two important candidate genes , and express protein parts of proteoglycans - lumican and decorin in extracellular matrix ( ecm ) .
proteoglycans can affect the growth of fibers and is closely related to sclerotic growth and function , whose alteration of expression is likely to affect scleral shape and in turn could lead to elongation of the eye axis and even the development of pm .   in this study ,
the purpose is to analyze sequences of all the exons and 5-regulatory region around the rs3759223 in the lumican gene and the exons 7 and 8 of decorin gene in individuals with pm and control subjects in the northern han ethnic chinese , and try to verify further the relationship between lumican , decorin genes and pm according to the recent disputable published paper [ 13 , 14 ] .
the subjects : 94 adult patients , including 12 pedigree cases ( figure 1 ) and 82 sporadic cases with pm ( < 6.00d ) and 90 controls , were recruited to study the relationships between the lumican , decorin genes and pm .
all the patients showed a changing of ocular fundus such as temperal crescent , pigment epithelium thinning , leopard retina , fuch 's macula , retina - choroidal atrophy , and so on , which were not found in all of the controls .
no participant had known ocular disease and injury that could predispose to pm , such as a history of retinopathy , prematurity , neonatal problems , a known genetic disease or connective tissue disorder associated with pm , such as stickler and marfan syndrome .
all cases and controls involved in this study had similar social backgrounds and were from the northern han ethnic chinese , with no ethnic subdivision .
the study was approved by the ethics committee of the dalian medical university , and adhered to the tenets of the declaration of helsinki .
blood samples were collected for genomic dna isolation after obtaining informed consent from the subjects .
the genomic dna was extracted from 5 to 10  ml of venous blood from all participants .
dna was purified from lymphocyte pellets according to standard procedures using a puregene dna isolation kit ( gentra systems , minneapolis , mn , usa ) .
the sequences corresponding to all the exons and 5-regulatory region around the rs3759223 in the lumican gene and the exons 7 and 8 of decorin gene were amplified by polymerase chain reaction ( pcr ) .
the pcr was performed in a 25  l reaction volume containing 2.5  l  10  gc buffer ( tiangen , beijing , and china ) , 200  mol / l of dntp , 0.2  mol / l of each primer , 1.0 unit of tag dna polymerase ( tiangen , beijing , and   china ) , and 60  ng of genomic dna .
the conditions , after initial denaturation at 95c   for 15 minutes , were 35 cycles of 30s at 94c , 1 minute at 50 to 62c , and 1 minute at 72c , followed by final extension at 72c for 7 minutes .
the products of pcr remained at 4c and were purified by using a multi screen - pcr plate ( millipore ) .
the purified pcr products were bidirectionally sequenced by using the abi 3700 dna sequencer ( applied biosystems , foster city , ca , usa ) .
the hardy - weinberg equilibrium ( hwe ) was tested with the chi - square (  ) goodness - of - fit test .
the frequencies of genotype and allele were also compared between the patients and control subjects by using the fisher chi - square analysis .
bonferroni 's correction was applied to adjust the significance level in multiple comparisons , and a p value of less than 0.017 ( equal to 0.05/3 ) was considered as statistically significant .
genotype distribution was in agreement with the hardy - weinberg equilibrium both in control subjects and patients ( p > .05 , data shown in table 3 ) .
mutation analysis by direct sequencing showed 5 mutations ( 4 for lumican gene and 1 for decorin gene ) which corresponded with snps previously reported in public databases ( table 3 ) .
.017 ) was located in the 5regulatory region ( 5rr ) of the gene ( 4006  bp ) , while rs17853500 ( t  c , n169n , p <
rs11105988 ( a  t , p > .017 ) and rs17018718 ( g  a , p > .017 ) were in the intron2 of lumican gene , and rs7441 ( t  c , p >
significant difference was shown for rs3759223 and rs17853500 between patients and control subjects ( direct sequencing figures shown as figures 2 , 3 , and 4 ) .
there is no significant difference for incidence of these mutations between pedigree and sporadic groups ( p > .017 ) .
nonsyndromic pm is a complex and common disorder that is likely attributed to alterations of multiple genetic factors .
indeed , 10 loci had been mapped for the disorder . among these , myp3 showed significant linkage of autosomal dominant pm to a locus at chromosome 12q2123 in a large german / italian family .
these small proteoglycans play an important role in regulating collagen fibril assembly and interaction and are intensely related to the structure and function of sclera [ 17 , 18 ] .
additionally , the human sclera had been shown to contain lumican and decorin [ 19 , 20 ] . in recent years ,   intense relationship between lumican ,   decorin genes and pm had been confirmed from animal experiments and dna analyzing of patients ' blood .
the defects observed in sclera collagen fibril diameter and organization in lumican - deficient mice were expected to lead to severe defects in ocular shape and size . in the lumican - null mice ,
the collagen fibrils were thinner , and the spatial distribution of the fibrils was less well organized than the wildtype . in the study of mice with a disrupted decorin gene , the fragile skin and abnormal tendon phenotypes initially observed were found to be due to fundamental alterations in collagen fibers .
accordingly , decorin was considered as a vital player in maintaining skin and tendon integrity at the molecular level .
another mouse study also implicated the proteoglycans - lumican and fibromodulin as functional candidate genes for high myopia .
research by analyzing dna of patients ' blood in taiwan indicated that an snp of the lumican gene might confer susceptibility to high myopia .
the snp ( rs3759223 ) of the lumican gene is located 4.406  bp upstream from exon 1 , and considered a putative regulatory element of the lumican gene .  
the mutations at 5 sites were found in our study : rs3759223 ( c  t ) , rs17853500 ( t  c ) , rs11105988 ( a  t ) , and rs17018718 ( g  a ) for lumican gene and rs7441 ( t  c ) for decorin gene .
rs3759223 is located -4006  bp in the 5regulatory region ( 5rr ) of lumican gene ( 4.406  bp upstream from exon 1 ) , and is considered a putative regulatory element of the lumican gene that influenced the promoter activities .
this research showed that variation ratio of rs3759223 was significantly higher in pm group than control group in the northern han ethnic group in china , which is infact compatible with the results obtained from lumican - deficient mice [ 18 , 21 ] , and analyzing dna of patients in taiwan .
although the association between rs3759223 and high myopia was not recently supported in chinese living in southeast china , it is worth notice that the genetic heterogeneity and the regional difference probably led to variation in genetics .
we thus surmise that rs3759223 could regulate the promoter activity of the lumican gene , and then affect the formation of collagen fibrils in the scleral coat during the development of pm in the northern han ethnic chinese .
rs17853500 located in exon 2 of lumican gene was a synonymous mutation ( n169n ) , which did not change sequences of amino acids and formation of protein .
rs11105988 , rs17018718 , and rs7441 did not show significant difference between pm cases and controls , which might be unrelated to development of pm , although rs7441 was found in the 3utr of exon 8 of decorin gene , which could regulate stability of transcript , subcellular localization , and translational level .
this study provided additional new insight into the genetics of pm , and suggested that rs3759223 in lumican gene expressed in the eye , might be among the genetic risk factors causing the pathogenesis of pm in northern han ethic chinese .
further research should be performed to confirm whether lumican is the virulence gene of pm , and how the mutation of lumican gene acts in the development of pm .
pathological myopia is a severe hereditary ocular disease leading to blindness . 
 it is urgent and very important to find the pathogenesis and therapy for this disease . 
 the purpose of the study is to analyze sequences of lumican and decorin genes with pathological myopia(pm ) and control subjects to verify the relationship between lumican , decorin genes and pm in northern han chinese . 
 we collected and analyzed the blood samples of 94 adults ( including 12 pedigree cases and 82 sporadic cases ) with pm and 90 controls in the northern han ethnic chinese . 
 genotyping was performed by direct sequencing after polymerase chain reaction(pcr ) amplification and allele frequencies were tested for hardy - weinberg equilibrium . 
 univariate analysis revealed significant differences between two groups for three snps : rs3759223 ( c      t ) and rs17853500 ( t      c ) of the lumican gene and rs74419 ( t      c ) of decorin gene with ( p < .05 ) for all their genotype distribution and allele frequency . there is no significant difference for incidence of these mutations between pedigree and sporadic group ( p > .05 ) . 
 the results suggested that the sequence variants in 5-regulatory region of lumican gene and 3'utr of decorin gene were associated significantly with pm in northern han chinese . 
 further studies are needed to confirm finally whether the two genes are the virulence genes of pm .