Implications of storing urinary DNA from different populations for molecular analyses.
BACKGROUND
Molecular diagnosis using urine is established for many sexually transmitted diseases and is increasingly used to diagnose tumours and other infectious diseases. Storage of urine prior to analysis, whether due to home collection or bio-banking, is increasingly advocated yet no best practice has emerged. Here, we examined the stability of DNA in stored urine in two populations over 28 days.


METHODS
Urine from 40 (20 male) healthy volunteers from two populations, Italy and Zambia, was stored at four different temperatures (RT, 4 degrees C, -20 degrees C & -80 degrees C) with and without EDTA preservative solution. Urines were extracted at days 0, 1, 3, 7 and 28 after storage. Human DNA content was measured using multi-copy (ALU J) and single copy (TLR2) targets by quantitative real-time PCR. Zambian and Italian samples contained comparable DNA quantity at time zero. Generally, two trends were observed during storage; no degradation, or rapid degradation from days 0 to 7 followed by little further degradation to 28 days. The biphasic degradation was always observed in Zambia regardless of storage conditions, but only twice in Italy.


CONCLUSIONS
Site-specific differences in urine composition significantly affect the stability of DNA during storage. Assessing the quality of stored urine for molecular analysis, by using the type of strategy described here, is paramount before these samples are used for molecular prognostic monitoring, genetic analyses and disease diagnosis.
Cannas
Angela
A
National Institute for Infectious Diseases L. Spallanzani, IRCCS, Roma, Italy.
Kalunga
Glendah
G
Green
Clare
C
Calvo
Ludovica
L
Katemangwe
Patrick
P
Reither
Klaus
K
Perkins
Mark D
MD
Maboko
Leonard
L
Hoelscher
Michael
M
Talbot
Elizabeth A
EA
Mwaba
Peter
P
Zumla
Alimuddin I
AI
Girardi
Enrico
E
Huggett
Jim F
JF
D000293:Adolescent; D000328:Adult; D002648:Child; D019411:Clinical Laboratory Techniques; D004247:DNA / Q000032:analysis / Q000652:urine*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D013048:Specimen Handling; D013696:Temperature; D013997:Time Factors
D004247:DNA