PRADER-WILLI / ANGELMAN’S SYNDROME: IMPRINTING / GENETIC

Imprinted genes are genes whose expression is determined by the parent (Imprinted Genes, 2011), according of biology dictionary is a phenomenon in which the phenotype of the offspring depends on the source of the chromosome containing the imprinted gene ( Biology-Online.org., 2010).

At a simple locus, only one allele is activate, deletion (imprinted/ inactivation by methylation) of this allele produce diseases (Le, Bhushan, & Grimm, 2011): Prader-Willi and Angelman’s syndrome, in both case the affected genes is in chromosome 15, also those syndromes can be occurs as a result of uniparental disomy (both chromosomes in a pair are inherited from the same parent).

Prader-Willi syndrome: deletion of normally active paternal allele. Le (2011).

Disorder caused by a deletion or disruption of genes in the proximal arm of chromosome 15. Present with diminished fetal activity, obesity, hypotonia, mental retardation, short stature, hypogonadotropic hypogonadism, strabismus, and small hands and feet. (Scheimann, 2011).

Angelman’s syndrome: deletion of normally active maternal allele. Le (2011).

Is a genetic disorder with characteristic features that include severe speech impairment, developmental delay, intellectual disability, and ataxia (Conrad Stoppler, 2011); also present seizures and inappropriate laughter( what is know as “happy puppet” ) Le (2011).

There is no specific therapy for Angelman’s syndrome as regards Conrad Stoppler (2011) , she refers that  a medical therapy for seizures is usually necessary. Physical and occupational therapies, communication therapy, and behavioral therapies are important in allowing individuals with Angelman’s syndrome to reach their maximum developmental potential.

Patients with Prader-Willi syndrome frequently require medical care for hypotonia or poor feeding, evaluation for hypogonadism or hypopituitarism, management of obesity, monitoring for scoliosis, and therapy for behavioral issues (Schluter, Buschatz, & Trowistzsch, 1997).

Bibliography

Biology-Online.org. (2010, august 20). biology online. Retrieved from http://www.biology-online.org/dictionary/Genomic_imprinting

Imprinted Genes. (2011, february 14). Retrieved from http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/I/Imprinting.html

Conrad Stoppler, M. (2011, december 8). MedicineNet.com. Retrieved from http://www.medicinenet.com/angelman_syndrome/article.htm

Le, T., Bhushan, V., & Grimm, L. (2011). First AID for USMLE step 1. usa: McGraw Hill.

Scheimann, A. (2011, june 8). Medscape.com. Retrieved from http://emedicine.medscape.com/article/947954-overview

Schluter, B., Buschatz, D., & Trowistzsch, E. (1997). Retrieved from respiratory control in children with Prader-Willi syndrome. Eur J Pediatr. Jan 1997; 156 (1):65-8: http://www.medscape.com/medline/abstract/9007495