Novel Vitamin D Receptor Mutations in Hereditary Vitamin D Resistant Rickets in Chinese

Hereditary vitamin D-resistant rickets (HVDRR) is one of the rare cases of autosomal recessive diseases that is mainly caused by gene mutations. In most cases, the mutations occur at the receptors for vitamin D (VDR) and are characterized by hypocalcemia and severe rickets. The heterozygous siblings and parents may appear normal without any observable symptoms of the disease. However, through a clinical observation, the patient can be diagnosed with hypocalcemia, rickets, and high serum levels in the body. The article on Novel Vitamin D Receptor Mutations in Hereditary Vitamin D Resistant Rickets in Chinese, explains that the primary form of mutation that leads to HVDRR disease is the VDR gene encoding mutation that eventually leads to the resistance of vitamin D in the body. This means that after the body has developed this form of resistance, the individual is vulnerable to diseases that can be prevented by the presence of vitamin D, meaning that the bodys immune system is affected.

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Any form of mutation that affects the VDR gene leads to its inability to function as required. Among the key roles of the VDR gene is the provision of instructions used in the making of the vitamin D receptor (VDR) protein, thus making it possible for the body to swiftly respond to vitamin D. This form of vitamin is readily available from the food intake and can also be achieved in the body with the help of sunlight. It is, therefore, necessary for the young children to be exposed to sunlight as this contributes to the manufacture of vitamin D, thus contributing to supplement that acquired through food intake. Vitamin D is essential for the body as it assists in the balancing of the necessary minerals such as phosphates and calcium that are used in the formation of teeth and bones. Therefore, vitamin D controls the digestive process of absorbing phosphates and calcium compounds from the gastrointestinal tract (intestines) to the bloodstream.

As explained in the article Novel Vitamin D Receptor Mutations in Hereditary Vitamin D Resistant Rickets in Chinese, VDR gene mutations directly lead to vitamin (D) dependent rickets (VDDR2), that is also referred to as the hereditary vitamin D-resistant rickets (HVDRR). It should be noted that these form of body disorder affects bone development due to less than the minimum required levels of phosphates (hypophosphatemia) and calcium (hypocalcemia) in the bloodstream. In the end, the patient develops weak and soft bones (rickets), and thus prone to fracture. In most cases, the affected have bowed legs, and this hinders their ability to walk in a normal (upright manner). The VDR gene mutations have direct and indirect effects on the VDR proteins. For instance, the VDR gene changes can cause a short version of abnormally in the VDR protein, or the development of an abnormal receptor that is not capable of binding to the calcitriol, to the DNA or the RXR. Even if there is sufficient calcitriol levels in the body, the altered VDR due to gene mutations cannot be able to trigger the absorption of the necessary minerals from the intestines. The resultant effect is that the absorption rate for calcium and phosphates is not optimal, leading to weak joints and bones. Therefore, the inability of these important body minerals to be absorbed into the bloodstream hinders bone mineralization, leading to weak and soft bones, and all other VDDR2 features. Calcium deficiency in the blood stream (hypocalcemia) leads to muscle weakness and even seizure for some individuals.

The article Novel Vitamin D Receptor Mutations in Hereditary Vitamin D Resistant Rickets in Chinese expressly explains that even if the HVDRR is considered as a rare case of rickets, it should not be downplayed because its effects are adverse. Some of the symptoms of the disease include muscle weaknesses, bone pain, and hypotonia. In such cases, the affected children develop walking problems, and this can be delayed. Such children undergo growth retardation and may end up developing teeth hypoplasia and dental caries that can be severe. The presence of Hypocalcemia in the body causes secondary hypophosphatemia and hyperparathyroidsism, inhibiting bone mineralization and eventually rickets. However, some patients can respond positively to treatment by using pharmacological doses that contain vitamin D. some of these dosages include 20200ug per day of 25(OH)D3 and 500040000IU per day. However, for those who cannot respond to the medication can be subjected to calcium therapy such as the intravenous infusion of calcium for children who completely fail to respond to the vitamin D derivatives.

From the article review above, three points have been learned and this is essential for career development as it offers relevant information on hereditary vitamin D-resistant rickets (HVDRR). As a result, the student comes to understand the causes of HVDRR and the possible solutions or preventive mechanisms. First, mutations that affect the functioning of the VDR gene hinders the production of important hormones in the body. For instance, VDR proteins are not produced optimally, leading to the inability of the body to respond to vitamin D. The second point is that body development, specifically bone formation and development is hindered if the VDR mutations occur. This is because of the minimum amount of hypophosphatemia and hypocalcemia in the body, leading to the development of weak and soft bones. The levels of phosphates and calcium should be maintained in the body at the recommended rate to ensure healthy bone formation. The third learning point is that a gene mutation that leads to the altering of the VDR affects the absorption rate of the essential nutrients to the bloodstream from the intestines during digestion. Therefore, there will be little or a low level of absorption of calcium and phosphates, making the patient has weak joints and bones.

Bibliography

David, Feldman, and Malloy J. Peter. "Mutations in the Vitamin D Receptor and Hereditary Vitamin D-resistant Rickets: BoneKEy Reports: Nature Publishing Group." Nature Publishing Group: Science Journals, Jobs, and Information. Last modified 2014.

Lee-Moay, Lim1 et al. "Novel Vitamin D Receptor Mutations in Hereditary Vitamin D Resistant Rickets in Chinese. - PubMed - NCBI." National Center for Biotechnology Information. Accessed June 28, 2016. http://www.ncbi.nlm.nih.gov/pubmed/26422470.

Malloy, P. J., J. W. Pike, and D. Feldman. "Hereditary 1, 25-dihydroxyvitamin D resistant rickets." Vitamin D. (2014): 765-787.

Malloy, Peter J., J. Wesley Pike, and David Feldman. "The Vitamin D Receptor and the Syndrome of Hereditary 1, 25-Dihydroxyvitamin D-Resistant Rickets 1." Endocrine reviews 20, no. 2 (2014): 156-188.

Malloy, Peter J., T. Ross Eccleshall, Coleman Gross, Lionel Van Maldergem, Roger Bouillon, and David Feldman. "Hereditary vitamin D resistant rickets caused by a novel mutation in the vitamin D receptor that results in decreased affinity for hormone and cellular hyporesponsiveness." Journal of Clinical Investigation 99, no. 2 (2014): 297.

U.S. National Library of Medicine. "Vitamin D-dependent Rickets." Genetics Home Reference. Last modified 2014. https://ghr.nlm.nih.gov/condition/vitamin-d-dependent-rickets.