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Background: Bone size is an important determinant of bone strength and is under strong genetic control. Objective: To identify quantitative trait loci (QTL) for areal bone size variation, a large-scale genomewide linkage scan was carried out in 451 Caucasian families. Participants and methods: Of 4124 people with phenotypes, 3899 were genotyped with 410 microsatellite markers. Multipoint linkage analyses were carried out in the entire sample, as well as in men and women separately. Potential epistatic interactions between identified genomic regions were also assessed. Results: Several potentially important genomic regions were identified, such as 8q24 for hip bone size (logarithm of the ratio of the odds that two loci are linked (LOD) 3.27) and 2p24 (LOD 2.04) for spine bone size. 8q24 may also interact with 19p13 to affect hip bone size. Several sex-specific QTL were also detected, such as 14q21 (LOD 2.94) for wrist bone size in women and 16q12 (LOD 2.19) for hip bone size in men. Conclusions: Together with previous findings, this study has further delineated the genetic basis of bone size and laid a foundation for future studies to eventually elucidate the mechanisms of bone size regulation and associated fracture risks. [ABSTRACT FROM AUTHOR]

Background: The vitamin D receptor (VDR) gene is important to human stature, as it mediates metabolic pathways, calcium homeostasis, and phosphate homeostasis, which influence growth. Methods: We examined the relationship between VDR and adult height in 1873 white subjects from 406 nuclear families. Four SNPs, namely -4817A/G at intron 1, Fokl C/T at exon 2 start codon, Bsml A/G at intron 8, and Taql T/C at exon 9 in VDR were tested for linkage and association with adult height variation by the program QTDT (quantitative transmission disequilibrium test). The bT haplotype of the Bsml and Taql loci was further tested far its association with height in unrelated samples randomly chosen from the 406 nuclear families by traditional population association methods. Results: All four tested SNPs were linked to adult height. Within family associations with height were detected at Bsml and Taql loci (p=0.048 and 0.039, respectively). Analyses based on Bsml/Taql haplotypes also revealed evidence for linkage (p = 0.05) and association (p = 0.001) with height. The bT haplotype was significantly associated with higher adult height (p = 0.033, within family association test). Such an association might be female specific and influenced by menstrual status. Conclusions: Our results strongly suggest that VDR may be linked to and associated with adult height variation in white popuations. [ABSTRACT FROM AUTHOR]

Background: Osteoporosis is a major public health problem, mainly quantified by low bone mineral density (BMD). The majority of BMD variation is determined by genetic effects. A pilot whole genome linkage scan (WGS) was previously reported in 53 white pedigrees with 630 subjects. Several genomic regions were suggested to be linked to BMD variation. Objective: To substantiate these previous findings and detect new genomic regions. Methods: A WGS was conducted on an extended sample where the size was almost tripled (1816 subjects from 79 pedigrees). All the subjects were genotyped with 451 microsatellite markers spaced -8.1 cM apart across the human genome. Two point and multipoint linkage analyses were carried out using the variance component method. Results: The strongest linkage signal was obtained on Xq27 with two point 100 scores of 4.30 for wrist BMD, and 2.57 for hip BMD, respectively. Another important region was 11 q23, which achieved a maximum LOD score of 3.13 for spine BMD in multipoint analyses, confirming the results on this region in Iwo earlier independent studies. Suggestive linkage evidence was also found on 7p14 and 20p12. Conclusions: Together with the findings from other studies, the current study has further delineated the genetic basis of bone mass and highlights the importance of increasing sample size to confirm linkage findings and to identify new regions of linkage. [ABSTRACT FROM AUTHOR]

Osteoporosis is a serious health problem in both Caucasians and Asians. Caucasians and Asians are two distinct major ethnic groups, which may have differential genetic determination underlying complex genetic diseases such as osteoporosis. However, to date, there has been no systematic review focusing on the aspect of ethnic difference in risk to osteoporosis and its potential underlying genetic determination between Asians and Caucasians. Here, we firstly review diverse aspects of osteoporosis-related differences, including the differences of epidemiology of osteoporotic fractures, peak bone mass, bone loss, bone area, bone geometry and drug treatment response between Asians and Caucasians. Then, we provide some potential genetic evidence on the different heritability and inheritance mode of bone phenotypes, the different osteoporosis candidate genes and the differential results in related molecular studies between them, to explain the above osteoporosis-related phenotypic differences. The results suggest that the osteoporosis-related phenotypic differences between Asians and Caucasians may be partially the result of the different ethnic genetic background. The present review may increase our understanding of potential different mechanisms related to ethnicity in pathogenesis of osteoporosis for effective and potentially customized treatments in different major ethnic groups.

Laser interference fringe visual acuities (IVAs) and E visual acuities (EVAs) of 116 cases 171 amblyopic eyes were examined. All cases were treated by various therapies and the average follow-up was 2.5 years. Before treatment, the IVAs of 86.5% eyes were better than their EVAs and the IVAs of 13.5% eyes were equal to their EVAs. After treatment, the EVAs of all the eyes were raised to their IVA levels (P < 0.0001, r = 0.8218). The results show that the IVA examination can predict the curative effect and monitor the treatment of amblyopia. The relationships between the IVA and the character of visual fixation, the type and degree of amblyopia, elder child and adult amblyopia, etc. were discussed.