Effects of formalin fixation, paraffin embedding, and time of storage on DNA preservation in brain tissue: a BrainNet Europe study.
There is a large amount of tissue stored in brain collections and brain banks, but little is known about whether formalin-fixed tissues and paraffin blocks stored for years in brain banks are suitable for the retrospective genetic studies. The study was carried out in order to: (i) compare DNA preservation in frozen, formalin-fixed and paraffin-embedded tissues stored for different periods; (ii) study point mutations and triplet expansions in frozen, formalin-fixed and paraffin-embedded material stored for variable periods, and using different fixative solutions; (iii) compare different methods to optimize DNA extraction and DNA amplification from suboptimally preserved brain tissue. DNA preservation is suitable for genetic studies in samples stored at -80 degrees C for several years. Formalin-fixed, paraffin-embedded tissue was inferior to frozen tissue, but did yield adequate results in many cases depending on the type of fixative solution and time of fixation before embedding. Prolonged fixation in formalin rarely yielded useful DNA. Similar results were obtained in samples from prion diseases. The best results were obtained by using the Qiagen kits (QIAmp DNA Micro) in frozen material, paraffin blocks and formalin-fixed tissue. Genomiphi and TaKaRa Ex Taq methods were also assayed in paraffin blocks and in formalin-fixed samples with limited success.
Ferrer
Isidre
I
Institut de Neuropatologia, Servei Anatomia Patològica, IDIBELL-Hospital Universitari de Bellvitge, Universitat de Barcelona, 08907 Hospitalet de Llobregat, Spain. 8082ifa@comb.es
Armstrong
Judith
J
Capellari
Sabina
S
Parchi
Piero
P
Arzberger
Thomas
T
Bell
Jeanne
J
Budka
Herbert
H
Ströbel
Thomas
T
Giaccone
Giorgio
G
Rossi
Giacomina
G
Bogdanovic
Nenad
N
Fakai
Peter
P
Schmitt
Andrea
A
Riederers
Peter
P
Al-Sarraj
Safa
S
Ravid
Rivka
R
Kretzschmar
Hans
H
D001921:Brain / Q000187:drug effects / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000302:isolation & purification; D016208:Databases, Factual; D005060:Europe; D005557:Formaldehyde / Q000737:chemistry; D006801:Humans; D016612:Paraffin Embedding; D011180:Postmortem Changes; D011309:Preservation, Biological; D013048:Specimen Handling / Q000379:methods; D013997:Time Factors; D016707:Tissue Fixation
D005557:Formaldehyde; D004247:DNA