Mixed gonadal dysgenesis associated with an isodicentric Y chromosome

A rare case of mixed gonadal dysgenesis with mosaicism 45, X/46, X, +mar

INTRODUCTION

We present a rare patient case with mixed gonadal dysgenesis as a disorder of sex development (DSD) and a new pattern of chromosome in the karyotype, 45, X/46, X, +mar(Y).

PRESENTATION OF CASE

A ten-year-old boy, raised in a nursery center, presented with ambiguous genitalia. Two cell lines, (45, X) and [46,X, +mar(Y)] were observed utilizing cytogenetic investigation including fluorescence in situ hybridization (FISH) which were carried out on his peripheral lymphocytes. A significantly higher percentage (75%) of Y-containing cells was observed in the blood, which could be considered the major reason why the case did not have distinct ambiguous genitalia. A further explorative laparoscopic procedure was performed, during which orchiectomy was performed, and remnants of Müllerian duct were excised.

DISCUSSION

A complete and sufficiently careful medical evaluation and genetics counseling of neonates is highly recommended in order to avoid any delayed insufficient diagnostic, conservative, and therapeutic care in children living with guardians rather than their biological parents. Both molecular and cytogenetic studies are recommended in some DSDs to help early diagnosis of the disease, which is important for further essential surgical approaches.

CONCLUSION

Cytogenetic studies followed by a laparoscopic exploratory and surgical survey are helpful tools for unraveling the mosaicism involving sex chromosomes and the complicated process in mixed gonadal dysgenesis patients.

[Prevalence and possible causes of hypospadias]

Hypospadias is the most common congenital malformation of the male external genitalia. After the heart and circulatory system, it is the second most common developmental disorder in males. It is due to a midline fusion defect of the male urethra, which results in a misplaced urethral meatus. Hypospadias may be distal, medial and proximal. It may occur as an isolated defect or it may develop together with other genital disorders (retention of testes in one or both sides, microphallus, bifid scrotum) or with malformation of other organs. In some cases syndromic forms may also occur. Genetic factors play a crucial role in the occurrence of early developmental defect, but endocrine and environmental factors may also be important in the aetiology of hypospadias. It may be associated with various sex and autosomal chromosomal abnormalities. Monogenic and chromosomal causes of hypospadias accounts for about in 30% of all cases, while genetic factors remain unknown in 70% of cases. The authors summarize the development of the male external genitalia, the prevalence and possible causes of hypospadias. They propose that better understanding of the pathogenesis of the disease may contribute to the prevention and decreased prevalence of the disease.

[Questions and dilemmas in the management of hypospadias]

Hypospadias is the second most common congenital malformation in males. Etiology remains unknown in about 70% of the cases. Distal hypospadias is considered not only developmental abnormality of the urethra in males, but it may also constitute a mild form of sexual development disorder in 46,XY males. Most urologists and endocrinologists consider that it is necessary to perform a detailed investigation of children presenting with proximal hypospadias associated with a small phallus or poorly developed scrotum and undescended testes. Currently, there is no generally accepted recommendation for the preoperative evaluation of hypospadias and, therefore, masculinizing surgery without preoperative evaluation is performed in these children. The authors summarize the international literature data and their own experience for the assessment and management of hypospadias concerning questions and problems related to preoperative investigation, masculinizing surgery and additional surgery. A detailed algorithm is presented for preoperative evaluation of both proximal and distal hypospadias.

Mixed gonadal dysgenesis in a patient with de novo tas(Y;19)(p11.3;q13.4) and 45,X mosaicism

We report a patient with a de novo telomeric association between chromosomes 19 and Y in conjunction with mixed gonadal dysgenesis. The patient was first admitted to the clinic because of abnormal external genitalia. Laparoscopic evaluation revealed (1) a rudimentary uterus, one fallopian tube, and a small gonad resembling an ovary on the right side, and (2) an immature fallopian tube, a vas deferens, and a gonad resembling a testis on the left side. Conventional cytogenetic analysis performed on cultivated peripheral blood cells, and tissue obtained from the phallus and a gonadal structure which resembled a testis revealed two different cell lines with the 46,X,tas (Y;19)(p11.3;q13.4) and 45,X karyotype. Y chromosome microdeletion analysis showed that the patient did not have any genomic deletions in the AZFa, b, c, or SRY regions on the long arm of the Y chromosome. This is the first report of a patient with mixed gonadal dysgenesis that is accompanied by a telomeric association between chromosomes 19 and Y with 45,X mosaicism.

Dysgenetic male pseudohermaphroditism

The authors report a case of a dysgenetic male pseudohermaphroditism with a 45,X/46,XY karyotype in a mosaic form, which was diagnosed in an infant. The one-week-old infant was evaluated because of proximal hypospadias and retention of the right testis. The results of hormonal tests were the followings: serum FSH 5.2 mU/ml; LH: 2.0 mU/ml; testosterone: 144.3 ng/dl; androstendione: 0.42 µg/l; 17-hydroxyprogesterone: 1.12 ng/ml. Chromosomal analysis revealed 45,X/46,XY karyotype. Fluorescent in vitro hybridization showed that 51% of the lymphocytes had the Y chromosome and the SRY gene. Analysis of the SRY showed no deletion in the AZF a,b,c regions. Pelvic magnetic resonance imaging indicated the presence of vagina between the bladder and the rectum, and it showed a mass measuring 15×8 mm in the right inguinal canal as well as an oval gonadal mass with a size of 13×7 mm in the left scrotum. During surgical intervention, performed at the age of one, the right gonad was removed and biopsy of the scrotal testis was performed. Histological examination revealed dysgenetic testis in both sides. The authors emphasize the necessity of cytogenetic and endocrinological investigations of newborns with perineoscrotal hypospadia and bilateral or unilateral maldescent testes immediately after birth. Surgical removal of the dysgenetic testicular tissue located in the abdominal cavity and its histological evaluation provides separation of mixed gonadal dysgenesis, dysgenetic male pseudohermaphroditism, bilateral gonadal dysgenesis and ovotestis in the 45,X/46,XY mosaic cases. An accurate evaluation is necessary for a correct sex assignment and for surgical intervention to prevent neoplastic degeneration of the dysgenetic gonad. Orv. Hetil., 2012, 153, 303–307.