X chromosomal abnormalities in Indian adolescent girls

Abstract

In girls of adolescent age, primary amenorrhea is a major problem and it is often suspected as Turner syndrome (TS), with complete or partial absence of one of the two X chromosomes. The girls who are unable to menstruate are primarily investigated by the gynecologists with the help of a physical examination, sonogram of the pelvis, endocrinologic tests, and ultimately cytogenetic analysis. Chromosomal analyses have been carried out in 280 such cases that were referred from different parts of the country. The standard protocol for peripheral blood lymphocyte culture was followed for metaphase chromosome preparation and conventional analysis of G-banded chromosomes. A total of 29% cases were found to have some chromosomal abnormality, including TS and testicular feminization syndrome involving sex chromosomes. Amongst those with sex chromosomal anomaly, 34% had evidence of a 46,XY karyotype in phenotypic females and 51% had pure line 45,X or mosaic with normal XX or other aberrations in X. The classification of the TS group further showed the spectrum of variant TS in Indian adolescent girls who suffered from absence or delayed menarche to correspond well with the Belgian, Danish, or Russian population. However, it has been reported that only 1% of the pure line 45,X conception is viable, indicating the necessity of mosaicism with X or Y chromosome. It has been understood that conventional banding analysis is absolutely necessary for segregating the variant nature of TS. In addition, molecular genetic or molecular cytogenetic investigations can determine the nature of mosaicism. The present study further indicated the involvement of autosomes in causing improper sexual development in girls of adolescent age.

Clinical profile and cytogenetic correlations in females with primary amenorrhea

“…We observed that these females developed SSCs and had normal gonadotropin levels. The frequency of normal karyotypes in our study falls within the previously reported range (65% to 85%) for the Indian population [1,2,[8][9][10][11][12][13][14][15][16].…”

“…Therefore, evaluating these abnormalities and providing genetic counseling for females is crucial for managing amenorrhea. The frequency of chromosomal abnormalities reported in previous studies ranges from 14% to 42% (Table 6) [1,2,4,5,[8][9][10][11][12][13][14][15][16][17][18].…”

“…a) Numerical mosaicism includes: mos 45,X[60]/47,XXX[11]/46,XX[29] (n=4), mos 45,X[53]/46,XX[47] (n=2), mos 45,X[81]/46,XY[19] (n=1), mos 45,X[64]/47,XXY[36] (n=1), mos 46,XY[90]/46,XX[10] (n=1); b) Structural mosaicism includes: mos 45,X[91]/46,X,+mar[9] (n=2), mos 45,X[71]/46,X,+mar[5 ]/47,XX,+mar[4]/46,XX[20] (n=1), mos 45,X[85]/46,X,i(X)(q10)[15] (n=3), mos 45,X[62]/46,X,der(X)t(X;X)(p22;p22.3)[38] (n=1), mos 45,X[78]/46,X,i(X)(q10)[12]/46,X,del(X)(q10)[8]/47,X,i(X)(q10),+mar[2] (n=1); c) Deletion in the X chromosome includes: 46,X,del(X)(q13) (n=2), 46,X,del(X)(p22.2) (n=1), 46,X,del(X) (q26) (n=1); d) Miscellaneous karyotype includes: 46,X,der(X)del(X)(q13q22)inv(X)(q23q27) (n=1), 46,XX,der(10)t(10;15)(p15;q22.1) (n=1), 46,XX,inv(9) (qh),del(18)(q12q21) (n=1), 46,XX,fra(16)(q22) (n=1), 47,XX,+mar (n=1).…”