Evaluation of Freeze Thaw Cycles on stored plasma in the Biobank of the Norwegian Mother and Child Cohort Study.

BACKGROUND: In many cohort studies, biological specimens are being stored without specific plans for analyses. In the Norwegian Mother and Child Cohort Study biological specimens (DNA, plasma, and whole blood) are stored on 96-well plates and as a result may undergo multiple freeze-thaw cycles. METHODS: To explore the impact of multiple freeze-thaw cycles on chemical constituents, we conducted a quality control study using pooled EDTA-plasma. Over a two-year period, samples stored at -80 degrees C were subjected up to 100 freeze-thaw cycles. Specimens were analyzed in triplicate for sodium, cholesterol, triglycerides, vitamin E, aspartate aminotransferase (AST), and free fatty acids. We assessed the percent change of analyte concentration from the values for the first freeze-thaw cycle, because this is the baseline for all stored specimens. RESULTS: With the exception of free fatty acids, there was little change over the first 10 freeze-thaw cycles. A majority of analytes showed no significant changes until 30 freeze-thaw cycles. After 30 freeze-thaw cycles, the largest percent change was observed for free fatty acids (+32%), AST (+21%), and triglycerides (-19%). CONCLUSIONS: Human plasma can go through several freeze-thaw cycles before analysis without influencing sample integrity for the selected analytes.

Cohort Profile Update: The Norwegian Mother and Child Cohort Study (MoBa).

This is an update of the Norwegian Mother and Child Cohort Study (MoBa) cohort profile which was published in 2006. Pregnant women attending a routine ultrasound examination were initially invited. The first child was born in October 1999 and the last in July 2009. The participation rate was 41%. The cohort includes more than 114 000 children, 95 000 mothers and 75 000 fathers. About 1900 pairs of twins have been born. There are approximately 16 400 women who participate with more than one pregnancy. Blood samples were obtained from both parents during pregnancy and from mothers and children (umbilical cord) after birth. Samples of DNA, RNA, whole blood, plasma and urine are stored in a biobank. During pregnancy, the mother responded to three questionnaires and the father to one. After birth, questionnaires were sent out when the child was 6 months, 18 months and 3 years old. Several sub-projects have selected participants for in-depth clinical assessment and exposure measures. The purpose of this update is to explain and describe new additions to the data collection, including questionnaires at 5, 7, 8 and 13 years as well as linkages to health registries, and to point to some findings and new areas of research. Further information can be found at [www.fhi.no/moba-en]. Researchers interested in collaboration and access to the data can complete an electronic application available on the MoBa website above.

The biobank of the Norwegian Mother and Child Cohort Study: a resource for the next 100 years.

INTRODUCTION: Long-term storage of biological materials is a critical component of any epidemiological study. In designing specimen repositories, efforts need to balance future needs for samples with logistical constraints necessary to process and store samples in a timely fashion. OBJECTIVES: In the Norwegian Mother and Child Cohort Study (MoBa), the Biobank was charged with long-term storage of more than 380,000 biological samples from pregnant women, their partners and their children for up to 100 years. METHODS: Biological specimens include whole blood, plasma, DNA and urine; samples are collected at 50 hospitals in Norway. All samples are sent via ordinary mail to the Biobank in Oslo where the samples are registered, aliquoted and DNA extracted. DNA is stored at -20 degrees C while whole blood, urine and plasma are stored at -80 degrees C. RESULTS: As of July 2006, over 227,000 sample sets have been collected, processed and stored at the Biobank. Currently 250-300 sets are received daily. An important part of the Biobank is the quality control program. CONCLUSION: With the unique combination of biological specimens and questionnaire data, the MoBa Study will constitute a resource for many future investigations of the separate and combined effects of genetic, environmental factors on pregnancy outcome and on human morbidity, mortality and health in general.

DNA extraction and HLA genotyping using mailed mouth brushes from children.

The need for blood samples in genetic epidemiologic studies often leads to low response rate among non-diseased individuals, and the collection of blood samples is costly and labor-intensive. We tested the feasibility of extracting DNA for human leukocyte antigen (HLA) typing from buccal cells collected with mailed, self-administered mouth brushes. A random sample of 1474 Norwegian children aged 0-17 yr was contacted by mail and received information about the study and mouth brushes for buccal cell samples. Brushes were returned by mail, DNA was extracted and the HLA-DQA1 and -DQB1 allelic polymorphisms were determined using polymerase chain reaction (PCR) and sequence-specific oligonucleotide probes. Mouth swabs were returned from 1068 (72.5%). Of these, DNA was extracted and HLA typing successfully completed for 1056 individuals (98.9%). In conclusion, we have described an efficient and safe set of methods for application in genetic epidemiologic studies of type 1 diabetes and other HLA-related diseases. A large proportion of randomly selected children returned self-administered mouth swabs with DNA of sufficient quality and quantity for HLA genotyping.