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In "Naming Jack the Ripper", Russell Edwards quotes Dr Jari Louhelainen's comments about the match between a segment of mitochondrial DNA obtained from the area of a possible blood stain on the "shawl" and the corresponding segment from a female-line descendant of Catherine Eddowes:
"One of these amplified mtDNA segments had a sequence variation which have a match between one of the shawl samples and Karen Miller’s DNA only; i.e. the DNA sequence retrieved from the shawl did not match with control reference sequences. This DNA alteration is known as global private mutation (314.1C) and it is not very common in worldwide population, as it has frequency estimate of 0.000003506, i.e. approximately 1/ 290,000. This figure has been calculated using the database at Institute of Legal Medicine, GMI, based on the latest available information."
Just over a week ago, Tracy I'anson posted an excerpt from a paper describing software designed to identify missing persons, which discusses the conventions for describing variations in the mitochondrial DNA sequence:
"An insert, such as the common extra “C” after base position 315 is listed as “315.1 C”. For matching purposes, the program tolerates errors in nomenclature for equivalent variants such as the extra C in the poly-cytosine region being reported as “314.1 C”."
The paper she quoted can be found here:
The authors refer to 314.1C as an "error in nomenclature". This is because 314.1C indicates that the measured sequence differs from the standard reference sequence for mitochondrial DNA by the insertion of one additional C (cytosine) after position 314 in the sequence. But the reference sequence actually has a string of five Cs in a row around here, in positions 311 to 315. The additional C could be inserted at any point in this string, and the resulting sequence - which is all that can be measured - would be exactly the same. The convention in forensic genetics is to describe the insertion as having occurred after the last possible position - that is, in this case, after position 315. So the conventional description for this mutation is 315.1C, not 314.1C.
The problem is that 315.1C is not a rare mutation, as the authors quoted by Tracy indicate. In fact the presence of an extra C in this position is much more common than its absence, because this is a case in which the reference sequence itself contains an uncommon mutation. The database referred to in the book can be found at http://empop.org/ and it indicates that 315.1C is present in 99.2% of the sequences which have information for this position.
It appears that something has gone badly wrong with the analysis here, and obviously the quoted figure of 1 in 290,000 can't be accepted without further explanation.
"One of these amplified mtDNA segments had a sequence variation which have a match between one of the shawl samples and Karen Miller’s DNA only; i.e. the DNA sequence retrieved from the shawl did not match with control reference sequences. This DNA alteration is known as global private mutation (314.1C) and it is not very common in worldwide population, as it has frequency estimate of 0.000003506, i.e. approximately 1/ 290,000. This figure has been calculated using the database at Institute of Legal Medicine, GMI, based on the latest available information."
Just over a week ago, Tracy I'anson posted an excerpt from a paper describing software designed to identify missing persons, which discusses the conventions for describing variations in the mitochondrial DNA sequence:
"An insert, such as the common extra “C” after base position 315 is listed as “315.1 C”. For matching purposes, the program tolerates errors in nomenclature for equivalent variants such as the extra C in the poly-cytosine region being reported as “314.1 C”."
The paper she quoted can be found here:
The authors refer to 314.1C as an "error in nomenclature". This is because 314.1C indicates that the measured sequence differs from the standard reference sequence for mitochondrial DNA by the insertion of one additional C (cytosine) after position 314 in the sequence. But the reference sequence actually has a string of five Cs in a row around here, in positions 311 to 315. The additional C could be inserted at any point in this string, and the resulting sequence - which is all that can be measured - would be exactly the same. The convention in forensic genetics is to describe the insertion as having occurred after the last possible position - that is, in this case, after position 315. So the conventional description for this mutation is 315.1C, not 314.1C.
The problem is that 315.1C is not a rare mutation, as the authors quoted by Tracy indicate. In fact the presence of an extra C in this position is much more common than its absence, because this is a case in which the reference sequence itself contains an uncommon mutation. The database referred to in the book can be found at http://empop.org/ and it indicates that 315.1C is present in 99.2% of the sequences which have information for this position.
It appears that something has gone badly wrong with the analysis here, and obviously the quoted figure of 1 in 290,000 can't be accepted without further explanation.
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