Frequently Asked QuestionsGeneral DNA, drug & alcohol frequently asked questions
Frequently Asked Questions
Below you will find a list of questions relating to DNA testing, drug testing or alcohol testing that we get asked on a regular basis:
What does “not excluded as the biological father” mean?
It means that the tested man (alleged father) has the DNA profile expected of the biological father. Therefore, the DNA paternity test result is consistent with the hypothesis that the tested man (alleged father) is the true biological father of the child.
What does “excluded” as the biological father mean?
It means that the tested man (alleged father) does not have the expected profile required to be the biological father. He is therefore highly unlikely to be the true biological father.
What does the “probability of paternity” mean?
This is the percentage likelihood that a man with the genetic markers (alleles) of the alleged father is the true biological father of the child as compared to an untested and unrelated man of the same ethnic origin.
How is a DNA test done?
The DNA test compares fragments of highly variable DNA, called Short Tandem Repeats (STR). Through a series of chemical reactions, DNA from each individual is extracted. Using a technique called PCR (Polymerase Chain Reaction); 24 STR markers from different chromosomes of the individuals tested are copied.
The products of the PCR are separated and measured to obtain a DNA profile. One-half of each person’s DNA information comes from their mother and the other half from their biological father. By comparing the DNA profiles of the child with the mother, it is possible to establish the shared STR markers between them. The child’s STR markers not found in the mother’s profile must therefore come from the biological father.
If the alleged father’s profile shares common STR markers with that of the child, then he is not excluded and may indeed be the true biological father. A statistical analysis is then carried out to calculate the probability of paternity. An alleged father is excluded as the biological father if STR markers found in his profile are not shared with the child. The tecnical data table lists each STR marker tested with the likleyhood of any matching DNA Patenrity Index (PI ).
What is the paternity index (PI)?
The paternity index compares the likelihood that an allele was passed on by the alleged father to the child, to the probability that a randomly selected unrelated man of similar ethnic background has passed that same allele on to the child.
What is the combined paternity index (CPI)?
This ratio indicates how many times more likely it is that the results of the DNA analysis would have been obtained given that the tested man (alleged father) is the true biological father of the child submitted rather than an unrelated man picked at random from the same ethnic population.
The CPI is based solely on genetic evidence and is determined by multiplying the individual PIs for each marker tested. The higher the CPI the more likley the tested man is the father.
Who will receive the results?
The test report(s) will be given to the person(s) who instructed the test and anyone who has taken part in the test (over the age of sixteen) is entitled to a copy of the results.
What happens to the DNA after the test is carried out?
The extracted DNA sample is destroyed by incineration three months after the report has been sent out.
What happens if I want to take my results to court?
If you need the results of the test for court or for other legal purposes, such as changing a birth certificate, then you will require our Legal DNA Test Service. Contact one of our friendly Customer Service advisers for further details.
How accurate is hair strand analysis?
AlphaBiolabs uses an analytical technique High Performance Liquid Chromatography tandem mass spectrometry (HPLC/MS/MS), which detects and quantifies drugs of abuse, enabling us to unambiguously differentiate between each individual drug we analyse for and their related compounds.
How can we assure the quality of the results?
AlphaBiolabs is accredited to ISO17025 by UKAS (the United Kingdom Accreditation Service) and also certified to the ISO 9001 standard. In addition to the in-house quality control procedures, we participate in external proficiency testing schemes (GTFCh and SoHT) that submit blind Quality Control samples to the laboratory and assesses the laboratory’s performance.
These quality measures ensure the analytical technique is complying fully with industry requirements, the application of best practice and the use of up-to-date methodology. The implementation of these standards provides assurance that the analyses are accurate and that AlphaBiolabs provides a high quality service.
Why should I choose a hair strand analysis?
Hair strand analysis is essential when you need to monitor a person with a suspected drug or alcohol abuse history over an extended period of time.
Depending on the length of the sample donor’s hair, hair strand analysis can provide a historical record of drug misuse/abstinence for up to 12 months (longer on some occasions).
Segmented analyses or an overview?
Segmented analyses are usually performed on a month-by-month basis. This method will allow you to observe patterns of use within an individual, i.e. an increase/decrease/cessation in drug use over time.
If you only require a drug test to provide an average result over a longer period of time (e.g. 3 months), then an overview analysis will provide this.
How soon after use can a drug be detected in hair?
It takes about 5 to 10 days for the hair containing the drug to grow above the scalp surface, and 2 weeks to be available for inclusion within a cut hair sample.
However, if you require a test to cover drug consumption during this most recent 2 weeks, we would recommend waiting at least 3 to 4 weeks before sample collection.
Can we detect the difference between prescription/over-the-counter drugs and illegal substances?
Yes, each drug has its own unique chemical structure and therefore has a different molecular ‘fingerprint’. Because of this, when the various drugs travel through the HPLC/MS/MS, they each move at different speeds and fragment in a unique pattern.
This means that each drug is unequivocally identified and cannot be confused with another drug (e.g. the use of lignocaine in dental treatment cannot give rise to a positive cocaine result etc.).
What happens if the sample donor has very little or no head hair?
Hair from other body regions, such as underarm and pubic hair can be used for drug testing purposes. However, growth rates of hair from body regions other than the head can vary and generally the dormant phase is greater.
Therefore deriving an accurate time frame associated with body hair samples is not possible. It can however be assumed that any drug use occurs within the total life cycle of the body hair, which can be up to 12 months. Furthermore, as body hair exhibits a larger amount of hair in the dormant phase than head hair, segmentation is not possible for body hair.
How does AlphaBiolabs establish its cut-off levels?
AlphaBiolabs uses the industry-wide accepted Society of Hair Testing (SoHT) guidelines for cut-offs and when SoHT cut-off levels aren’t available, in-house cut-offs are applied. These in-house cut-offs are based on the instrument performance.
How much hair is needed for testing?
Approximately 50-60 strands are required for testing, which is approximately the width of a thin pencil. If the head hair sample is collected from the most appropriate site (the crown of the head), it should make no or minimal cosmetic difference.
What about environmental exposure to a drug?
Passive exposure to environments heavily laden in a drug may give rise to detectable levels of the drug in the hair through smoke and/or direct contamination (i.e. the drug being in direct contact with the hair e.g. by contaminated hands).
Although the possibility that this scenario will cause false positive results cannot be completely removed, safeguards are put in place to significantly reduce the possibility of this occurring. These include; the application of recommended cut-off levels, chemical washing of the hair three times prior to analysis (to remove/reduce any drug that may be present on the surface) and, in most cases, the detection of the drug itself and its metabolite (providing supporting evidence that a drug has been directly ingested by an individual).
Can chemical treatments on the hair affect the results?
Cosmetic hair treatments (such as dyeing, bleaching and perming) have been shown to significantly damage the cuticle or degrade incorporated drugs, leading to a reduction in the amount of a drug contained within the hair.
The extent of the loss will depend on the cosmetic treatment used and the drug present. Therefore, sample donors who are occasional users of drugs may potentially give negative test results. However, more frequent drug users may still test positive but the levels of the detected drugs would be less than if the hair was untreated.
Can dread-locked hair be analysed?
Yes, there is no problem in testing the hair for drugs. However, depending on the condition of the hair, we may not be able to measure and segment it accurately. Consequently, it may not be possible to provide an accurate time frame to the hair analysed.
What is chronic and excessive alcohol consumption?
According to the World Health Organisation (WHO), chronic excessive alcohol drinking corresponds to an average consumption of 60 grams of pure ethanol per day, over several months (this equates to around 7.5 units of alcohol, or approximately 3 pints of beer or 2 to 3 large glasses of wine per day).
What is a Liver Function Test?
Liver Function Tests (LFT) are commonly used as a general indicator of liver disorder, reflecting possible hepatocyte injury or cholestasis (blockages or damage in the biliary system), but the results themselves can give clues to the causes of liver damage.
Historically, an increase of Gamma GT (one of the enzymes monitored in an LFT) has been used to indicate chronic and excessive alcohol consumption.
Indeed, it has been reported that for a healthy individual, at least 60 grams of alcohol per day, for a minimum of four weeks is required before an elevation of GGT may be observed, but that only 30–50 percent of excessive drinkers in the general population will show an increased Gamma GT result.
It is strongly recommended therefore to use the LFT results in combination with results from other tests such as CDT in blood and ETG and FAEE in hair. An LFT test can only give a result representing approximately four weeks prior to sample collection.
Can medications affect LFT results?
It is published in the scientific literature that prescription and non-prescription drugs such as non-steroidal anti-inflammatory drugs (NSAIDs), antibiotics and anticonvulsants among others can cause an elevation of the blood Gamma GT level.
However, it is not possible to determine who will be affected in this way when they start a medication. This is why a GP will often monitor an individual’s liver function (by performing LFT) following their introduction to a new medication in order to monitor and ensure that the consumption of the drug is not causing additional problems within the liver.
What is a CDT test?
Transferrin is a glycoprotein made in the liver and is responsible for carrying iron in the bloodstream. Transferrin usually contains four to six carbohydrates. When alcohol is consumed excessively and chronically, the liver has difficulty building transferrin molecule correctly.
Indeed, carbohydrates are not attached as they should be to transferrin (i.e. Carbohydrate Deficient Transferrin, or CDT are created). It is generally accepted that it takes the daily consumption of more than 60 grams of alcohol for a minimum of 1–2 weeks to increase CDT concentrations to an abnormal level.
It should be noted that an episodic binge drinking session is unlikely to cause an elevation of the CDT concentration in the blood.
A CDT test can only give a result representing approximately four weeks prior to sample collection.
Blood alcohol tests in pregnant and post-partum women
Performing LFT and CDT analyses are not advised in pregnant women, particularly in the final trimester as the findings could be misleading. Indeed, it has been reported that during the final trimester of pregnancy, increasing ALP and decreasing GGT values can be observed.
Furthermore, due to the changes in blood volumes and the circulatory system of a pregnant woman, it is advised that as a general principle CDT should not be measured. LFT and CDT testing should not be started again until they are at least 8 weeks post-partum.
Blood alcohol tests following blood transfusions
Following blood transfusions, an individual could have a significant proportion of someone else’s blood in the system. Therefore, there is potential for the recipient of the blood transfusion to have blood results that are skewed.
Indeed it is also advised to wait at least 2 months following a blood transfusion before starting LFT and CDT testing again.
What are FAEE and EtG hair alcohol tests?
Following the consumption of alcohol, Ethyl Glucuronide (EtG) and Fatty Acid Ethyl Esters (FAEE) are formed in the liver as part of the breakdown of alcohol in the body.
These compounds are then distributed around the body and a small portion become incorporated in hair (via different routes). The hair can then be analysed for these compounds and compared against Society of Hair Testing (SoHT) recommended cut-off levels (for either a 3 cm or 6 cm long segment of hair from the root).
Levels of EtG and FAEE above the cut-off are consistent with the excessive and chronic consumption of alcohol during either the 3 or 6 month period of investigation.
Why should I get EtG and FAEE tests in combination?
Although both EtG and FAEE hair analyses have shown a high sensitivity and a high specificity for the determination of chronic and excessive alcohol consumption, it has been well documented that these tests each have their own limitations.
This includes the possible removal of water soluble EtG through very regular washing and/or false positive FAEE findings due to the direct application of cosmetic products containing alcohol (such as hairspray, mousse, gel and wax).
It is issues such as these (and others) that led to the ruling of LB Richmond v B & W & B & CB (2010) EWHC 2903 (Fam), which recommends that:
- When used, hair tests should be used only as part of the evidential picture and the hair analysis findings should not be used in isolation but in conjunction with all evidence for the case including witness reports, other tests performed, and any clinical assessments carried out.
- Because of the respective strengths and weaknesses of EtG and FAEE tests, if hair tests are being undertaken, both tests should be used.