Myotonic+muscular+dystrophy

====**Name of disease: ** //Steinert disease, or m////yotonic// muscular dystrophy (DM)- Muscle disease ==== ====**Root cause of disease: ** It is a human genetic disease caused by trinucleotide repeat expansion (TNRE) on chromosome 19. It refers to the repeat of a 3 nucleotide sequence, in this case, CTG. It is autosomal dominant inheritance, which means it is transmitted from parents to offspring without mutation. However, persons with TNRE disorder, the numbers of copies of CTG increases above the unaffected level, aboout 5-37 copies at the 3’ untranslated region (3’-UTR) of the gene (**1**). There are two types of DM, DM I and DM II. Type I is caused by the CTR expansion at 3’UTR of dystrophia myotonica-proteinkinase gene (DMPK). The number of copies caused minimum effect was 50, while in severe cases, the number was several kilobase pairs (**2**). On the other hand, DM II was caused by several thousand copies of CCTG expansion at the 3’UTR of the zinc finger protein 9 (ZNF9) gene (**3**). ====
 * [[image:untitled.JPG width="495" height="190"]] ||
 * **Figure 1**: The phenomenon of trinucleotide repeat of CTG, which causes myotic muscular dystrophy. ||

**Affected cell types/tissues/organs/systems:** MD affects voluntary and involuntary muscles. It causes the inability to relax muscles at will (Greek: myotonia) (**4**).
====**Historical background: ** The disease is called MD for its Greek name, //muscular dystrophy// which means progressive muscle degeneration. It was originally described by a German doctor in 1909, so it was named after him, //Steinert disease (**4**).// ==== ====**Common symptoms: **Inability to relax as will, difficulty in breath due to weakened heart muscle, difficulty in swallow, abnormality of cognitive functioning in children which causes difficulty in speaking, hearing and vision…(**4**) ==== ====**Standard treatments: **Researchers are looking for the ways to minimize the expansion of DNA in DMPK gen (DM I) and the ZNF9 gene (DM II) (**4**). ==== ==== John Hopkins Hospital offers a treatment by a group of health care professionals such as neurologist, cardiologists, pulmonologist, and ophthalmologist. The inability to relax muscles will be treated with mexiletine (**5**). ==== ====**Current research: ** The sequence expansion is believed to cause the abnormal change in mRNA structure which causes fault expression of protein (**1**). Blech-Hermoni et al. studied RNA binding protein to regulate gene expression in heart development (**6**), so numbers of copy of TNRE can be controlled. Orpana et al. provided a development in DM diagnosis by suggesting novel technique using PCR-based flatform for molecular diagnosis for DM I (**7**). ====

**References: **
====**1) ** <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Brooker et al.(2009)//Genetics Analysis&Principles,// 3rd ed, pp429-430. Boston, MA: McGraw-Hill. ==== ==== **<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">2) ** <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Brook JD, McCurrach ME, Harley HG, Buckler AJ, Church D, Aburatani H, et al. Molecular basis of myotonic dystrophy: expansion of a trinucleotide (CTG) repeat at the 3’ end of a transcript encoding a protein kinase family member. <span class="ref-journal" style="font-family: 'Times New Roman',serif; font-size: 12pt;">Cell. <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">1992; <span class="ref-vol" style="font-family: 'Times New Roman',serif; font-size: 12pt;">68 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">:799–808. ==== ====**<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">3) ** <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Liquori CL, Ricker K, Moseley ML, Jacobsen JF, Kress W, Naylor SL, et al. Myotonic dystrophy type 2 caused by a CCTG ex <span style="font-family: 'Times New Roman',Times,serif;">pansion in intron 1 of ZNF9. Science. 2001; 293:864-7. ====

<span style="font-family: 'Times New Roman',Times,serif;">4) Myotonic Muscular Dystrophy-Overview. Retrieved December 8, 2013, from []
====<span style="font-family: 'Times New Roman',Times,serif;">5) Neurology and Neurosurgery: Myotonic Muscular Dystropphy. Retrieved on December 8, 2013, from [] ==== ====<span style="font-family: 'Times New Roman',Times,serif;">6) Blech-Hermoni, Y., & Ladd, A. N. (2013). RNA binding proteins in the regulation of heart development. The international journal of biochemistry & cell biology, 45(11), 2467–78. doi:10.1016/j.biocel.2013.08.008 ==== ====<span style="font-family: 'Times New Roman',Times,serif;">7) Orpana, A. K., Ho, T. H., Alagrund, K., Ridanpää, M., Aittomäki, K., & Stenman, J. (2013). Novel heat pulse extension-PCR-based method for detection of large CTG-repeat expansions in myotonic dystrophy type 1. The Journal of molecular diagnostics : JMD, 15(1), 110–5. doi:10.1016/j.jmoldx.2012.07.004 ==== = =