Molecular investigation of two male subjects with short stature and a 45,X/46,X,ring(Y) karyotype

Characterization of a rare mosaic X-ring chromosome in a patient with Turner syndrome

BACKGROUND

Ring chromosomes can be formed by terminal breaks of two arms of a chromosome and their rejoining, leading to a loss of genetic material. They may also be formed by telomere-telomere fusions with no deletion, resulting in the formation of a complete ring. Mosaic X-ring chromosomes are extremely rare and have highly variable phenotypes. Here, we report a case with a mosaic X-ring chromosome in a patient with Turner syndrome, and we illustrate the unreported complicated mechanism using chromosome analysis and fluorescence in situ hybridization (FISH).

CASE PRESENTATION

A 10-year-old girl of short stature presenting Turner syndrome was admitted to our hospital. The patient's clinical characteristics were subsequently documented. Genetic analysis showed a karyotype of mostly 45,X[140]/46,X,r(X)[60]. The X ring chromosome was cytogenetically characterized as 45,X/46,X,r(X)(p22.32q21.1), with a length of approximately 74 Mb.

CONCLUSIONS

Taken together, we report a rare case with a mosaic X ring chromosome in Turner syndrome and we believe this case expands our collective knowledge of mosaic structural chromosomal disorders and provides new insight into clinical management and genetic counseling for Turner syndrome.

Molecular analysis of ring y chromosome in a 10-year-old boy with mixed gonadal dysgenesis and growth hormone deficiency

Ring Y chromosome is a very rare chromosomal aberration. The published mixed gonadal dysgenesis (MGD) patients with a ring Y chromosome are short in stature, but are not growth hormone (GH) deficient. We present the molecular cytogenetic and molecular characterization of ring Y chromosome mosaicism in a 10-year-old boy with MGD whose short stature could be explained by the high percentage of cells monosomic for the X-chromosome, but also by the presence of severe GH deficiency. The ring Y chromosome in our patient is a de novo structural aberration. The father's karyotype was normal.

Phenotypic spectrum of 45,X/46,XY males with a ring Y chromosome and bilaterally descended testes

OBJECTIVE

To characterize the phenotypic spectrum of males with bilaterally descended testes and a 45,X/46,X,(r)Y karyotype.

DESIGN

Retrospective review of patient records; cytogenetic and molecular analysis.

SETTING

Tertiary medical center setting.

PARTICIPANT(S)

Five males, two prepubertal and three postpubertal, with a 45,X/46,X(r)Y karyotype and bilaterally descended testes.

INTERVENTION(S)

Linear growth evaluation, testicular endocrine and exocrine studies, cytogenetic and molecular analysis on each patient.

MAIN OUTCOME MEASURE(S)

Clinical phenotype versus genotype.

RESULT(S)

Both prepubertal males had short stature and low testosterone. All three adults had normal puberty and normal testosterone levels. Two of the adults (one with short stature and one with normal stature) had elevated gonadotropins and azoospermia. The third adult had normal stature, severe oligospermia, normal gonadotropins, and normal serum testosterone.

CONCLUSION(S)

The phenotypic spectrum of males with a 45,X/46,X(r)Y karyotype and bilaterally descended testes varies greatly from males with short stature and spermatogenic failure to males without short stature and less severely affected spermatogenesis. This broad spectrum of phenotypic findings needs to be taken into account when the clinical geneticist encounters a prenatal diagnosis of a 45,X/46,X(r)Y karyotype. This information will also be helpful for pediatric and reproductive endocrinologists in counseling males with bilaterally descended testes and a 45,X/46,X(r)Y karyotype.

Deletion of the long arm of the Y chromosome in an adolescent with short stature and hypogonadism

We describe a patient with short stature more than that expected for non-treated congenital adrenal hyperplasia due to nonclassic 21-hydroxylase deficiency with deletions in the long arm of the Y chromosome including the CGY gene and the AZF subregions.