| Allele | Phenotype | Mechanism |
| 1991 | ||
|---|---|---|
| standard CO | Co(a+) Co(b-) Co3+ | standard sequence |
| 1992 | ||
| 1993 | ||
| 1994 | ||
| CO*02 | Co(b+) Co(a-) Co3+ | Single missense mutation |
| CO*M.01 | Co3+ weak Co(a-) Co(b-) | Single missense mutation |
| CO*N.01 | Co:-3 Co(a-) Co(b-) | large deletion |
| CO*N.02 | Co:-3 Co(a-) Co(b-) | Short insertion |
| 1995 | ||
| 1996 | ||
| 1997 | ||
| 1998 | ||
| 1999 | ||
| CO*01N.03 | Co(a-) Co(b-) Co:-3 | Single missense mutation |
| 2000 | ||
| 2001 | ||
| CO*01N.04 | Co:-3 Co(a-) Co(b-) | Short deletion |
| 2002 | ||
| 2003 | ||
| 2004 | ||
| 2005 | ||
| 2006 | ||
| 2007 | ||
| 2008 | ||
| 2009 | ||
| 2010 | ||
| Co(A45T) | Co(b+) Co(a-) | Single missense mutation |
| CO(Q47R) | Co:-4 Co(a-) Co(b-) Co3+ | Single missense mutation |
| CO*01N.05 | Co(a-) Co(b-) | Single missense mutation |
| 2011 | ||
| 2012 | ||
| CO*01N.06 | Co(a-) Co(b-) Co:-3 | Short deletion |
| 2013 | ||
| 2014 | ||
| 2015 | ||
| 2016 | ||
| 2017 | ||
| 2018 | ||
| 2019 | ||
| 2020 | ||