Results of the 1999-2000 collaborative exercise and proficiency testing program on mitochondrial DNA of the GEP-ISFG: an inter-laboratory study of the observed variability in the heteroplasmy level of hair from the same donor.
The Spanish and Portuguese working group (GEP) of international society for forensic genetics (ISFG) 1999-2000 collaborative exercise on mitochondrial DNA (mtDNA) included the analysis of four bloodstain samples and one hair shaft sample by 19 participating laboratories from Spain, Portugal and several Latin-American countries. A wide range of sequence results at position 16,093 of the HV1 (from T or C homoplasmy to different levels of heteroplasmy) were submitted by the different participating laboratories from the hair shaft sample during the first phase of this exercise. During the discussion of these results in the Annual GEP-ISFG 2000 Conference a second phase of this exercise was established with two main objectives: (i) to evaluate the incidence of the HV1 sequence heteroplasmy detected in Phase I across different sample types from the same donor including blood, saliva, and hair shafts, (ii) to perform a technical review of the electropherograms to evaluate the relative levels of heteroplasmies obtained by the different laboratories and also to examine the source of possible errors detected in Phase I. Anonymous review of the raw sequence data permitted the detection of three transcription errors and three errors due to methodological problems. Highly variable levels of heteroplasmy were found in the hair shaft and more stability in blood and saliva. Three laboratories found variable levels of heteroplasmy at position 16,093 across adjacent fragments from the same hair shaft. Two laboratories also described more than one heteroplasmic position from a single hair. The relevance of these findings for the interpretation of mtDNA data in the forensic context is also discussed.
Alonso
Antonio
A
Departamento de Madrid, Instituto de Toxicología, Sección de Biología, Luis Cabrera 9, 28002 Madrid, Spain. biologia@mad.inaltox.es
Salas
Antonio
A
Albarrán
Cristina
C
Arroyo
Eduardo
E
Castro
Azucena
A
Crespillo
Manuel
M
di Lonardo
Ana María
AM
Lareu
María Victoria
MV
Cubría
Carlos López
CL
Soto
Manuel López
ML
Lorente
José A
JA
Semper
Marta Montesino
MM
Palacio
Ana
A
Paredes
Manuel
M
Pereira
Luisa
L
Lezaun
Anna Pérez
AP
Brito
José Pestano
JP
Sala
Andrea
A
Vide
María Conceiçao
MC
Whittle
Martín
M
Yunis
Juan J
JJ
Gómez
Josefina
J
D001801:Blood Stains; D019411:Clinical Laboratory Techniques / Q000592:standards*; D004272:DNA, Mitochondrial / Q000097:blood / Q000737:chemistry / Q000235:genetics*; D005554:Forensic Medicine / Q000379:methods*; D005819:Genetic Markers; D006197:Hair / Q000737:chemistry*; D006801:Humans; D007373:Interinstitutional Relations; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D011174:Portugal; D011786:Quality Control; D015203:Reproducibility of Results
D004272:DNA, Mitochondrial; D005819:Genetic Markers