親子関係について

Paternity denial probability

親子鑑定　NIPPT　DNA鑑定　

↓今すぐDNA出生前親子鑑定を予約する↓

簡単WEB予約はこちら

The calculation of the probability of paternity negation is used in DNA paternity testing to indicate the likelihood that a father is not the genetic father of a particular child. This includes calculations using Probability of Exclusion (PE) and Paternity Index (PI).

1. Basic concept of paternity negative probability

Paternity denial probability indicates the probability that a particular man is denied the possibility of being the biological father of a child based on the results of a DNA test. This probability is calculated based on the match or mismatch of genetic markers shared between the child and the presumed father.

2. The concept of probability of exclusion (PE)

The probability of exclusion (PE) is the probability that if the presumed father is not the father of the child, this can be detected by DNA testing.PE is determined based on the number of genetic markers used and the likelihood that these markers differ. The more markers and the higher the accuracy, the higher the PE.

3. Calculation of the Paternity Index (PI)

The Paternity Index (PI) quantifies the evidence of paternity at a particular locus; the PI is calculated by comparing the probability of a particular allele being transmitted from father to child with the probability of it being transmitted from an unrelated male unrelated to the mother.

  • PI is calculated for each locus (STR: short repeat sequence) and the PI of all loci is multiplied together to give the overall PI.

4. Formula for calculating the probability of paternity denial

The paternity negative probability is calculated using the paternity positive probability (W).

(1) Calculation of paternity affirmation probability

The paternity affirmation probability (W) is calculated by the following equation:

  • PI: Overall paternity index.
  • PE: Probability of exclusion

(2) Calculation of paternity denial probability

The paternal negative probability is calculated as follows:
Paternal negative probability = 1 – W
That is, the complement of the paternal positive probability is the paternal negative probability. The paternal negative probability is calculated as follows:
Paternal negative probability = 1 – W
That is, the complement of the paternal positive probability is the paternal negative probability.

5. Specific examples

If the overall paternity index (PI) is 1000 and the probability of exclusion (PE) is 0.99 (99%), the paternity affirmation probability is calculated as follows.

The paternity negative probability is:
1 – 0.99999 = 0.00001 (0.001%)The paternity negative probability is:
1 – 0.99999 = 0.00001 (0.001%)

This means that the paternity negative probability is 0.001%.

6. Use in actual paternity testing

In actual paternity testing, there are many factors that influence the analysis, including the number of genetic markers used and whether maternal DNA is included. Typically, more than 20 STR markers are used to confirm or deny paternity with a high degree of accuracy.

Summary

The calculation of the paternity negative probability is based on the probability of exclusion (PE) and the paternity index (PI).Using these figures, the probability of not being the father is quantified and the final negative probability is obtained.

医師監修 監修日：2024年9月18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9月18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

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

  1. Gjertson DW, Brenner CH, Baur MP, Carracedo A, Guidet F, Luque JA, et al. ISFG: Recommendations on biostatistical evaluation of patterns in forensic parentage testing. Forensic Sci Int Genet. 2007;1(3-4):223-231.
  2. Essen-Möller E. Die Beweiskraft der Ähnlichkeit im Vaterschaftsnachweis; theoretische Grundlagen. Mitt Anthrop Ges Wien. 1938;68:9-53.
  3. Wiener AS, Lederer M, Polayes SH. Studies in isohemagglutination: IV. On the heredity of the MN types. J Immunol. 1930;19(3):259-282.
  4. Lo YMD, Corbetta N, Chamberlain PF, Rai V, Sargent IL, Redman CWG, et al. Presence of fetal DNA in maternal plasma and serum. Lancet. 1997;350(9076):485-487.

Latest Articles

Supervisor of the article

Dr. Hiroshi Oka

Director of CAP Laboratory

Graduated from Keio University, Faculty of Medicine

Doctor of Medicine

Medical Doctor