Considerations on ethical aspects  in forensic ChrX typing

Ø Introduction to forensic
          ChrX-research

Ø Go to the ChrX STR via 
           idiogram

Ø Go to the ChrX STR via 
          the linkage table

Ø Go to STR clusters via ChrX-
           idiogram

Ø Diallelic ChrX-markers
          (a project of the future)

Ø      Ethical considerations

Ø submit data

Ø Calculate ChrX STR
           parameteres

Ø      Glossary

Ø useful links

Ø    ChrX users

Ø ChrX bibliography

Gonosomal aberrations and Testicular Feminisation
When gonosomal aberrations or instances of testicular feminisation are detected, ChrX typing is no longer a valid means of kinship testing. In any case, it appears worthwhile emphasising that such findings, when inadvertently obtained during kinship testing, fall under the duty of confidentiality. Disease-relevant information should not be revealed to an affected individual unless they explicitly ask for it.

Background:
In several countries, such as Germany, forensic scientists follow the principle that forensic DNA testing should not disclose diseases or genetic risks. This principle is fully complied with STR typing strategies using the well established autosomale STRs, such as the CODIS markers, chromosome Y (ChrY) markers, mtDNA analysis and nearly all established chromosome X (ChrX) markers. ChrY and mtDNA typing may reveal some general information as to a person's ethnic origin, however, this cannot be considered as an intervention into the person's privacy.
In principle, the same applies to gender identification typing ChrX and ChrY markers. However, chromosomal aberrations such as the Klinefelter Syndrome may be recognised when ChrX markers are used. This complex disorder is linked to the chromosomal genotype 46XXY or other numerical aberration of the ChrX and may be recognised  by heterocygocity of ChrX markers in a male person . Genotype X0 is associated with the Ullrich-Turner syndrome. This may be diagnosed when females show (virtual) homogosity in all ChrX STRs investigated.
Furthermore the, ANDROGEN INSENSITIVITY SYNDROME  (known under the alternative titles  TESTICULAR FEMINIZATION SYNDROME; ANDROGEN RECEPTOR DEFICIENCY or DIHYDROTESTOSTERONE RECEPTOR DEFICIENCY) can be recognised when a persons female phenotype is linked not with a female genotype (XX) but with the male counterpart  XY.
 

HUMARA

We announce here that our group no longer considers HumARA to be a suitable DNA marker in forensic casework.

Background:
Desmareis et al. [1] used HumARA typing as a starting point for generating special formulae for applying ChrX typing to forensic practice. Hence, these markers are well established in forensic DNA typing. From the very beginning of HumARA testing it has been known that, in contrast to all other forensic DNA markers, the HumARA CAG repeat is located in a coding region (androgen receptor gene, exon 1). This means that the repeat codes for a polyglutamine tract. La Spada et al. [2] proved that X-linked spinal and bulbar muscular atrophy (SBMA) is attributable to a mutation at this locus. This disease occurs at trinucleotide repeat lengths longer than 43.
Apart from the SBMA disease, HumARA typing can detect a number of further health risks, e.g. increased risk of impaired spermatogenesis, risk of breast, endometrial, colorectal, and prostate cancer.
http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=313700

 1.      Desmarais D, Zhong Y, Chakraborty R, Perreault C, Busque L (1998) Development of a highly polymorphic STR marker for
        identity testing purposes at the human androgen receptor gene (HUMARA). J Forensic Sci 43: 1046-1049.
2.        La Spada AR, Wilson EM, Lubahn DB, Harding AE, Fischbeck KH (1991) Androgen receptor gene mutations in X-linked
        spinal and bulbar muscular atrophy. Nature 352: 77-79.