Ping Lin

X-linked dominant Conradi-Hunermann syndrome is one of a group of disorders with aberrant punctate calcification in cartilage, or chondrodysplasia punctata. This is most prominent around the vertebral column, pelvis and long bones in CPDX2. Additionally, CDPX2 patients may have asymmetric rhizomesomelia, sectorial cataracts, patchy alopecia, ichthyosis and atrophoderma. The phenotype in CDPX2 females ranges from stillborn to mildly affected individuals identified in adulthood. CDPX2 is presumed lethal in males, although a few affected males have been reported. We found increased 8-cholestenol and 8-dehydrocholesterol in tissue samples from seven female probands with CDPX2. This pattern of accumulated cholesterol intermediates suggested a deficiency of 3β-hydroxysteroid- Δ8,Δ7-isomerase, which catalyses an intermediate step in the conversion of lanosterol to cholesterol. A candidate gene encoding a sterol-Δ8-isomerase has been identified and mapped to Xp11.22-p11.23. Using SSCP analysis and sequencing of genomic DNA, we found EBP mutations in all probands. We confirmed the functional significance of two missense alleles by expressing them in a sterol-Δ8- isomerase-deficient yeast strain. Our results indicate that defects in sterol-Δ8-isomerase cause CDPX2 and suggest a role for sterols in bone development.

Following the recent literature on institutions and economic growth, we examine the effects of property rights protection on corporate R&D. Using a unique 2003 World Bank survey of over 2400 firms in 18 Chinese cities, we obtain the following findings: (1) property rights protection is positively and significantly related to corporate R&D activity (for both process and product R&D); (2) government services and helping hand are conducive to corporate R&D, while informal payments to government officials are not; and (3) government ownership of firms and direct appointment of CEOs are negatively associated with corporate R&D activities. We also find that corporate R&D is positively related to firm size, and access to finance, but negatively related to product market competition and firm age.