Total finger ridge count and 45, X mosaicism (with and without Y chromosome)

We have observed that in patients with 45, X mosaicism without a Y chromosome, the influence of the 45, X cell line on the total finger ridge count (TFRC) may be pronounced enough to produet a markedly elevated count, whereas in patients with 45, X mosaicism with a Y, the TFRC may not be significantly increased. We have reviewed 21 of our cases of 45, X mosaicism (14 cases without Y and 7 cases with Y) in an attempt to test our observation. The TFRC of 14 cases of 45, X mosaicism without Y (mean of 167.3) is very significantly increased (P < 0.001) over 15 normal female controls (mean of 116.2), whereas the TFRC of 7 cases of 45, X mosaicism with Y (mean of 152.0) shows no significant difference (P > 0.05) from the 10 normal control males (mean of 138.4). These results have thus far confirmed our hypothesis. The finding of a high TFRC may also be used as a clinical indication of the existence of a 45, X cell line in a mosaic without a Y chromosome.