Một số ví dụ quan trọng của rối loạn chuyển hóa và di truyền có ảnh hưởng đến xương được liệt kê trong Bảng 48-10. Osteogenesis imperfecta (giòn xương) được đặc trưng bởi sự mong manh bất thường của xương. Các scleras thường bất thường mỏng và mờ và có thể xuất hiện màu xanh do sự thiếu hụt của mô liên kết. | THE EXTRACELLULAR MATRIX 551 Table48-10. Some metabolic and genetic diseases affecting bone and cartilage. Disease Comments Dwarfism Often due to a deficiency of growth hormone but has many other causes. Rickets Due to a deficiency of vitamin D during childhood. Osteomalacia Due to a deficiency of vitamin D during adulthood. Hyperparathyroidism Excess parathormone causes bone resorption. Osteogenesis imperfecta eg MIM 166200 Due to a variety of mutations in the COL1A1 and COL1A2genes affecting the synthesis and structure of type I collagen. Osteoporosis Commonly postmenopausal or in other cases is more gradual and related to age a small number of cases are due to mutations in the COL1A1 and COL1A2 genes and possibly in the vitamin D receptor gene MIM 166710 Osteoarthritis A small number of cases are due to mutations in the COL1A genes. Several chondrodysplasias Due to mutations in COL2A1 genes. Pfeiffer syndrome1 MIM 100600 Mutations in the gene encoding fibroblast growth receptor 1 FGFR1 . Jackson-Weiss MIM 123150 and Crouzon MIM 123500 syndromes1 Mutations in the gene encoding FGFR2. Achondroplasia MIM 100800 and thanatophoric dysplasia2 MiM 187600 Mutations in the gene encoding FGFR3. 1The Pfeiffer Jackson-Weiss and Crouzon syndromes are cran-iosynostosis syndromes craniosynostosis is a term signifying premature fusion of sutures in the skull. 2Thanatophoric Gk thanatos death phoros bearing dysplasia is the most common neonatal lethal skeletal dysplasia displaying features similar to those of homozygous achondroplasia. MANY METABOLIC GENETIC DISORDERS INVOLVE BONE A number of the more important examples of metabolic and genetic disorders that affect bone are listed in Table 48-10. Osteogenesis imperfecta brittle bones is characterized by abnormal fragility of bones. The scleras are often abnormally thin and translucent and may appear blue owing to a deficiency of connective tissue. Four types of this condition mild extensive severe and variable have been .
