Human gene Essay Example | Topics and Well Written Essays - 750 words

Human gene - Essay Example This paper attempts to explore the organization, structure, history and regulatory elements associated with the GALT gene, and understand how a mutation will lead to occurrence of galactosemia. GALT is the official symbol for the galactose-1-phosphate uridyl transferase gene. The position of GALT is 13 on the shorter p arm of the chromosome 9. The more exact molecular positioning of GALT on chromosome 9 can be described as starting at base pair 34,646,585 till ending at base pair 34,650,594 (Genetics Home Reference). The organization of GALT encompasses 11 exons spanning approximately 4-4.3 kb. The GALT gene encodes proteins with a 43 kDa molecular mass, consisting of about 379 amino acids length. Two molecules or a dimer make up an active GALT enzyme and contain a molecular mass of around 88 kDa. It has been found that disruption in the Q188R region is the most common mutation found to cause classic galactosemia with a relative frequency of 60%. It is because a His-Pro-His motif is present at exon 6 in the functional site, which significantly impairs the entire gene functioning if mutation occurs proximal to this region of the gene (Calderon, 939-40). People with classic galactosemia have been identified with over 180 mutations in the GALT gene. The structural illustration of GALT gene is presented in fig 01. Figure 01. GALT Gene Structure. Source: AGCOH (2009). The genetic deficiency is inherited in an autosomal recessive manner requiring the copy of GALT sequence from both carrier parents (Elsas). Though the incidence rate of GALT deficiency is different among nations, about 1 in every 62 000 has been estimated in pan-ethnic populations. The incidence rate in travelers from the Irish populations is also significant (Murphy et al., 550). The GALT gene is responsible for the synthesis of GALT enzyme in the liver. The GALT enzyme catalyzes the breakdown of galactose-1-phosphate into available glucose as an energy source in the second step of the Leloir metaboli sm pathway (Reichardt, 194). Galactose is a product of the larger sugar Lactose found in all milk and dairy products. The reaction also produces UDP-galactose that is further employed in the formation of sugar containing proteins and fats. These galactose-containing proteins and fats have multiple roles in various body functions such as chemical signaling pathways, construction of cell structure, molecule transportation and energy production (Genetics Home Reference). The GALT enzyme reveals a ping-pong, bi-bi kinetics that describes the binding of one domain of enzyme with uridine diphosphate (UDP) glucose, which forms enzyme-UDP-glucose intermediate. The uridine monophosphate stays attached to GALT and the glucose-1-phosphate becomes free. The GALT uridine monophosphate then binds galactose-l-phosphate to develop GALT-UDP-galactose. The UDP-galactose becomes free of the GALT, and allows it to cycle the next reaction (Elsas and Lai, 40). The failure of GALT enzyme to metabolize gal actose results in building up of Galactose-1-phosphate to toxic levels in the body, which can give rise to several health issues such as jaundice, feeding issues, weight faltering, liver damage, bleeding, hyperammonemia, sepsis, infections, cataracts, dyspraxia, ovarian failure, and neural abnormalities