Deletion Essay -- Biology, DNA

Deletion is a mutation in which a part of the chromosome or the DNA is absent or lost. It may be inherent, or it may be due to improper chromosomal crossing-over during meiosis. This deletion is responsible for the abnormalities in the patient. One of the known disorders seen due to deletion is the Wolf-Hirschhorn syndrome. Wolf-Hirschhorn syndrome (WHS), first described by Wolf et al[1] and Hirschhorn et al[2], results from the hemizygous deletion of the distal short arm of chromosome 4. Due to the complex and unmarked expression of this disorder, the WHS syndrome is presumed to be a contiguous gene syndrome with an indeterminate number of genes responsible for the phenotype i.e. a multigenic etiology. [3][4] The size of the terminal deletion may vary from a subtle 1.4Mb to a classic 30Mb [5]. Earlier genotype-phenotype correlation studies reveal that the main characteristic feature of WHS - the ‘Greek warrior helmet face’, is caused due to the hemizygosity of the WHSC1 gene located in the WHS critical region (WHSCR).[5] Various other genes are also located in the WHSCR which are responsible for most other phenotypic features. More precisely, the Wolf-Hirschhorn syndrome critical region (WHSCR) is located at 4p16.3 region. Approximately 25% of the patients with WHS deletion in this region are not detectable by cytogenetic karyotyping [6]. Hence, FISH has to be performed. The prevalence of this syndrome is estimated to be 1 in 50,000 births [7] with a female to male ratio of 2:1[8]. Case report: A baby was born with low birth weight of 1.8 kg to a 36 yr old father and 32 yr old mother. The proposita is the 6th girl child of the non-consanguineous parents. As can be seen from the pedigree chart shown in figure 2, the mothe... ...infant with Wolf-Hirschhorn syndrome: a dilemma in determination of the optimal timing of delivery. Clinical Medicine: Case reports. 8. Society for the Study of Behavioral Phenotypes (SSBP) Information sheet: Wolf-Hirschhorn syndrome. Registered Charity number 1013849. 9. Altherr, M.R., Bengtsson, U., Elder, F. F. B., Ledbetter, D. H., Wasmuth, J. J., McDonald, M.E., Gusella, J. F., Greenberg, F. Molecular confirmation of Wolf-Hirschhorn syndrome with a subtle translocation of chromosome 4. Am. J. Hum. Genet. 49: 1235-1242, 1991. [PubMed: 1746553] 10. Althea T. Impact of chromosome 4p-syndrome on communication and expressive language skills: A preliminary investigation. Language, Speech and Hearing Services in Schools. Vol 41 265-276 July 2010. 11. Harold Chen. EMedicine Specialties> Pediatrics: Genetics and Metabolism Disease> Genetics. Updated Jun 16, 2009.