Methods of DNA extraction from hair follicles.

The extraction of DNA from hair follicles is used in a variety of situations, including criminal investigations and to confirm parent-child relationships. The following is the general procedure.

Sample collection: the hair is pulled out and the hair follicles at its base are sampled. These hair roots are rich in DNA and are suitable for testing.
Cytolysis: in order to extract DNA from the hair follicles, the cells must first be degraded. This is done using the enzyme proteinase K, which breaks down the cell membrane and cell nucleus, releasing the DNA. This process usually takes place in a temperature-controlled incubator for several hours.
DNA purification: the DNA released from cells is mixed with other cellular components. Methods such as phenol-chloroform extraction and silica column purification are used to purify this DNA. This yields pure DNA.
PCR amplification: if the DNA obtained is in small quantities, it is amplified to ensure that it is sufficient for analysis. Polymerase chain reaction (PCR) is used to replicate specific regions of DNA and increase them to the quantity required for testing.
Analysis: finally, purified DNA is used for genetic analysis and DNA profiling. This enables confirmation of parent-child relationships and personal identification.

Relationship with prenatal paternity testing.

Prenatal paternity testing confirms the parent-child relationship with the potential father while the fetus is still inside the mother’s body. This is done by using maternal blood, amniotic fluid or chorionic villi to extract the fetus’ DNA and compare it with that of the father. Non-invasive methods that analyze free fetal DNA (cfDNA) in maternal blood are commonly used.

Prenatal paternity testing and DNA extraction from hair follicles have one thing in common: both use DNA to confirm parent-child relationships. Both methods have in common that DNA is extracted and analyzed using techniques such as PCR. However, the specimens used are different. As prenatal paternity testing involves the DNA of the fetus, methods are used to collect DNA directly from the fetus (amniotic fluid or chorionic villus sampling) or indirectly from the mother’s blood (cfDNA).

DNA extraction from hair follicles is primarily used for postnatal paternity testing. Unlike prenatal paternity testing, DNA from hair follicles is obtained from a direct sample and is therefore non-invasive yet highly accurate. Prenatal paternity testing, on the other hand, requires careful procedures to ensure that the fetus’ DNA is safely extracted from the mother’s body. Non-invasive NIPPT has become an important technique for confirming parent-child relationships without any risk to the mother or the fetus.

Conclusion

DNA extraction from hair follicles is a very effective method in confirming parent-child relationships and personal identification, and is widely used in criminal investigations and forensic medicine. Mean while, prenatal paternity testing is developing methods to confirm parent-child relationships using fetal DNA, with the non-invasive NIPPT receiving particular attention. With the development of these technologies, we can look forward to a future where our lives are safer and where individual genetic information is used appropriately. HIRO Clinic offers DNA collection from hair follicles. Please understand that this costs an additional JPY 33 000.

医師監修監修日：2024年8月30日

岡博史（おかひろし）

医師・医学博士／ヒロクリニック統括院長

YouTubeチャンネルなどを通じて、遺伝子やNIPT（新型出生前診断）についてわかりやすく発信しています。

略歴

1996年慶應義塾大学医学部卒業
2004年慶應義塾大学医学博士号取得
2005年慶應義塾大学皮膚科学教室助手
2008年ヒロ皮フ形成クリニック開業
2009年医療法人社団福美会理事長
2015年医療法人社団福美会理事

資格・所属

CAPラボディレクター
日本皮膚科学会皮膚科専門医
日本医師会産業医
東京衛生検査所指導監督医

発信・関連リンク

この記事は、ヒロクリニックNIPPTの編集・監修体制にもとづき、資格を持つ医師が内容を確認しています。

医師監修監修日：2024年8月30日

堤修一（つつみしゅういち）

医師・医学博士／ヒロクリニック博多駅前院院長

略歴

1993年東京大学医学部医学科卒業
2016〜2019年東京大学先端科学技術研究センター准教授

発信・関連リンク

プロフィール詳細

この記事は、ヒロクリニックNIPPTの編集・監修体制にもとづき、資格を持つ医師が内容を確認しています。

参考文献

Higuchi R, von Beroldingen CH, Sensabaugh GF, Erlich HA. DNA typing from single hairs. Nature. 1988 Apr 7;332(6164):543-6.
Linch CA, Smith SL, Prahlow JA. Evaluation of the human hair root for DNA typing. J Forensic Sci. 1998 Nov;43(6):1161-5.
Hellmann AP, Niemczura M, Borys S, Shonova N, Pawłowski R. Forensic evaluation of DNA typing from hair shafts. Forensic Sci Int. 2001 Jun 15;118(2-3):99-103.