Background: The isodicentric Y (idic Y) is one of the most common aberrations of the Y chromosome. Most patients (pts) are chromosomal mosaics, including 45,X cell line.
Objective and hypotheses: Our aim is to describe clinical and molecular features of our 45,X/46,Xidic(Y) cases.
Method: We retrospectively evaluate the clinical description of nine cases (six females, one male, two with ambiguous genitalia) with mosaic karyotype 45,X/46,Xidic(Y) referred to our Centre in the last 23 years.
Results: Main clinical features were: Turner stigmata (eight pts), delayed or incomplete pubertal development in six females (F), short stature (eight pts), malformations in 7/9 (congenital heart disease, horseshoe kidney). The two pts with ambiguous genitalia (AG) both have hypospadias, unilateral cryptorchidism and undervirilization; 2/6 F showed clitoral hypertrophy. Seven pts showed Mullerian remnants (6 F and 1 AG), wolffian structures (2 F) and urogenital sinus (1 AG). 6/9 pts (4 F, 2 AG) underwent gonadectomy to reduce the risk of gonadoblastoma. Gonads histology: streaks in 3/4 F, dysgenetic testis in the M, mixed gonadal dysgenesis (1 AG, 1 F), atrophic testis (other AG). In 3/6 subjects, we obtained karyotype from gonads. The pts with Turner stigmata, short stature and the other malformations showed a predominance of peripheral 45,X cell line, that also predominates on the streak gonads. On dysgenetic testis we found higher % of 46,Xidic(Y) cell line. In 1/4 F, we found difference between blood and gonads percentage of 45,X: >93% 45,X cells in gonads vs 40% in blood.
Conclusion: Our data seems to confirm that phenotypic variability and sexual differentiation of these cases are explained by the degree of mosaicism, particularly in gonads. To improve the genotype/phenotype correlation is useful to analyze more than one tissue and to perform histological and karyotype studies of the gonads when it is possible.
20 - 22 Sep 2014
European Society for Paediatric Endocrinology