Recessive autosomal disorder

A recessive autosomal disorder is a genetic disorder caused by a genome containing two recessive alleles, one inherited from the mother and one from the father^[1] . The word autosome shows that the gene is located on one of the organisms autosomes^[2] as opposed to on a sex chromosome.For offspring to display this type of disorder the parents must have either been carriers having one recessive and one wildtype allele or have suffered from the recessive autosomal disorder also. 

If both parents are a carrier of the disorder then there is a 1/4 chance that the child will be born with the autosomal recessive disorder. This can be shown through genetic crossing on a punnett square:

	F	f
F	FF	Ff
f	Ff	ff

In this punnett square (F) is dominant meaning no disorder is coded for and (f) is recessive and this allele codes for the disorder. The cross shows that when two carriers with the genotype (Ff) have a child there is only 25% chance of the child having the autosomal recessive disorder compared to 50% chance of them being a carrier and 25% chance of no recessive alleles at all.

Examples of recessive autosomal disorders^[3]:

• Cystic fibrosis 
  
• Sickle cell anaemia
• Tay-Sachs

References

1. ↑ Clark, Heather MS (2014) , Autosomal Recessive: http://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=90&ContentID=P02142 (last accessed 27.11.14)
2. ↑ Genetics Home Reference (2014): Autosome, http://ghr.nlm.nih.gov/glossary=autosomefckLRLast accessed 27.11.14
3. ↑ Goodman S (1998) Table of genetic disorders, http://www.kumc.edu/AMA-MSS/Study/table_of_genetic_disorders.htmfckLRLast accessed 27.11.14