explanatory Essay
1336 words
1336 words

Polydactyly is a medical term used to describe extra fingers on hands or toes at birth it’s called a congenital anomaly (Biesecker,2012). The physical extra fingers may be small and nonfunctional or can be a fully working finger, existing in different places on the hands and feet (Biesecker,2012). The organelle that causes this disease is cilia, which are slender, microscopic, hair like organelles, found in eukaryotic cells (Ciliopathy Alliance,2010). They are located all around the exterior of the cell, in the lining of the trachea, and in female human fallopian tubes (Summers,2015). Cilia propel an organism by a pull and recovery stroke method and they are used to capture food, accomplishing this by waving in a consecutive order, thus generating …show more content…

In this essay, the author

  • Explains that polydactyly is a medical term used to describe extra fingers on hands or toes at birth. cilia are microscopic, hair-like organelles found in eukaryotic cells.
  • Explains the diagnosis of polydactyly, which is made during the initial physical examination at birth.
  • Explains that the defect in primary cilia causing polydactyly is an error in the coding for the receptor protein.
  • Explains that ttc8 is a protein coding gene, only found in humans, produced by alternative splicing. it is linked to polydactyly because it is expressed in ciliated cells.
  • Explains that polydactyly is a mutation in the dynein arms in cilia that causes problems in normal skeletal patterning. future research will be conducted at the national human genome research institute

Primary cilia function as cellular antennae that receive signals from the environment and transmit them to the cell body to control many important cellular functions (Brown,2014). Hedgehog signaling (transmits info to embryonic cells required for proper development) is dependent on IFT (intraflagellar transport) in cilia required for normal skeletal patterning during development (Brown,2014). The receptor protein (GAS11) for this pathway is found in the ciliary membrane, also known as a specialized membrane, which is crucial for successful ciliary function to be carried out (Adam-Day,2015). GAS11 is a component of the dynein regulatory complex, attached to the outer doublets (Adam-Day,2015). Mutations in the outer doublets or central pair may end up leading to more severe symptoms. When GAS11 isn’t present and synthesized properly then it can lead to defective dynein arm activity. If that happens then the cilia’s function won’t be carried out, which explains why mutations in outer dynein arms are so frequently seen as the cause of Primary Ciliary Dyskinesia (PCD) in patients as well as Polydactyly. The main function of cilia is to propel an organism around, but there are several more functions that cilia do (Ciliopathy Alliance,2010). They also capture food and sweep …show more content…

TTC8 contains several tetratricopeptide repeats (TRPs) involved in protein-protein interactions (Stoetzel,2005). This coding gene is linked to Polydactyly because it is expressed in ciliated cells and it is involved in the formation of cilia (Katsanis N.,2003). Researchers sequenced the coding regions of TTC8 in 35 BBS families of different ethnical backgrounds. Genotype-phenotype correlation was explored in patients with identified mutations (Bin,2009). To date only 3 families out of a series of 128 BBS families were reported to have TTC8 mutations (Stoetzel,2005). Two of the three families have a homozygous mutation and the third family has a heterozygous mutation. Mutations in TTC8 account for only a minority of BBS families approximately around 2%. The first family was consanguineous of North African descent with 3 BBS affected sibs (blood related) as well as 3 non-affected sibs. The affected sibs contained homozygous splice-site mutation, which affects the last G on exon 4 of TTC8. Family two had an irregular case of Lebanese background. Proband born from a consanguineous marriage. The affected sibs contained homozygous splice-site mutation on exon 6 of TTC8. Polydactyly is believed to depart from classical autosomal recessive mode and might

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