DNA analysis of sex chromosomal aberration: curious mutation found in Turner syndrome

Abstract

The clear evidence that curious fashion of mitochondrial DNA (mtDNA) inheritance was reported in sex chromosomal aberration. Human mtDNA is located outside the nucleus of the cell producing energy for the cell. In the recent years, mtDNA is being used in forensic DNA identification because each cell has many copies of mitochondria, and is easy to be amplified by PCR. Human mtDNA has polymorphic sites in hypervariable regions (HVR) I, II and III. However, human mtDNA evokes some problems, such as heteroplasmic point mutations and questionable maternal inheritance. To investigate this phenomenon, we had a chance to perform a mtDNA testing on 1-month-old infant, diagnosed as Turner Syndrome which was confirmed to be 45XO karyotype by X-STR testing. As a result, two remarkable evidences were obtained. The first, an intermarriage, is seemed to be related in the genesis of the sex chromosomal aberration. The second, the exact maternal inheritance of mtDNA was not maintained in Turner syndrome, as well as in Klinefelter syndrome reported by us previously. In these cases, although paternal influence of mtDNA inheritance was deniable, mutations of mother's mtDNA were excluded or repaired to the usual type in child's mtDNA.