Distamycin A-DAPI banding of nonfluorescent Y (Ynf) chromosomes in 45,X/46,XYnf mosaicism

Summary The distamycin A-DAPI banding patterns of nonfluorescent, nonheterochromatic Y chromosomes (Y^nf) in two patients with 45,X/46,XY^nf mosaicism were investigated. In both cases moderately fluorescent bands were observed near the centromere and on the distal long arm of the Y^nf. These bands were similar to the centrometric band on normal Y chromosomes and support the hypothesis that the Y^nf is an isodicentric chromosome derived from the proximal portion of the Y chromosome.     

True hermaphroditism in 45,X/46,XY mosaicism.

This report discusses the clinical findings on two patients with 45,X/46,XY mosaicism, two boys presented with penile hypospadias and cryptorchidism. A dysgenetic ovary and a testis were found in one boy, and a dysgenetic ovary in the other. Both patients can be considered to be true hermaphrodites on the basis of histology and clinical and hormonal observations. 45,X/46,XY mosaics have a wide range of phenotypic appearances and their gonadal morphology can also show great differences. However, the incidence of true hermaphroditism in individuals with 45,X/46,XY mosaicism is low and the reports in the literature rare. It is likely that males with 45,X/46,XY who suffer only mild maldevelopment of the external genitalia will not be recognized. In all patients with penoscrotal hypospadias and cryptorchidism with 45,X/46,XY mosaicism, the possibility of true hermaphroditism should be considered.     

Prenatal diagnosis of 45,X/46,XX mosaicism and 45,X: implications for postnatal outcome.

The prognosis for 45,X/46,XX mosaicism diagnosed prenatally has yet to be established. We report our experience with 12 patients in whom prenatal diagnosis of 45,X/46,XX mosaicism was detected by amniocentesis for advanced maternal age or decreased maternal serum alpha-feto protein and compared them with 41 45,X/46,XX patients diagnosed postnatally. The girls in the prenatal group range in age from 3 mo to 10 years. All have had normal linear growth. Four had structural anomalies including: ASD (n = 1); ptosis and esotropia (n = 1); labial fusion (n = 1); and urogenital sinus, dysplastic kidneys, and hydrometrocolpos (n = 1). Gonadotropins were measured in seven; one had elevated luteinizing hormone/FSH at 3 mo of age. One has developmental delay and seizures as well as ophthalmologic abnormalities. None would have warranted karyotyping for clinical suspicion of Turner syndrome. The prevalence of 45,X/46,XX mosaicism is 10-fold higher among amniocenteses than in series of postnatally diagnosed individuals with Turner syndrome, which suggests that most individuals with this karyotype escape detection and that an ascertainment bias exists toward those with clinically evident abnormalities. The phenomenon of a milder phenotype for the prenatal group is similar to that observed for 45,X/46,XY diagnosed prenatally. Prenatal counseling for 45,X/46,XX in the absence of such ultrasound abnormalities as hydrops fetalis should take into account the expectation of a milder phenotype (except, possibly, with respect to developmental delay) than that of patients ascertained postnatally. The same does not hold true for 45,x diagnosed prenatally.     

A case of true hermaphroditism with 45X/46XY mosaicism

Summary The authors describe a case of true hermaphroditism of mainly female phenotype, ambiguous external genitalia, and ovotestis. The cytogenetic studies revealed 45X/46XY mosaicism and an absence of Barr bodies.     

The phenotype of 45,X/46,XY mosaicism: an analysis of 92 prenatally diagnosed cases.

We undertook an international survey of prenatally diagnosed 45,X/46,XY mosaicism to ascertain the phenotypic spectrum of this condition. Ninety-two cases were obtained by means of a questionnaire sent to over 730 cytogenetic laboratories. Seventy-six cases (75 males and 1 female) had physical examinations after delivery or termination of pregnancy. Among these, there were four significant genital anomalies: three hypospadias and one female with clitoromegaly. Gonadal histology was abnormal in three (27%) of 11 cases, all of whom had normal male external genitalia. Other anomalies were noted in five cases: one cystic hygroma in a male, two cardiac anomalies, one spina bifida with multiple other defects, and one intrauterine growth retardation. There was no relationship between the percent mosaicism and the presence or degree of abnormalities. We conclude that 95% of 45,X/46,XY fetuses will have normal male genitalia, although there will also be a significant risk (27%) for abnormal gonadal histology. Long-term follow-up studies of prenatally diagnosed cases of 45,X/46,XY mosaicism are needed to study, without ascertainment bias, stature, pubertal development, tumor risk, and fertility.     

Cell division and sister chromatid exchanges in 45,X/46,X,i(Xq) mosaicism

Summary The kinetics of cell division and sister chromatid exchanges were studied in PHA-stimulated short-term cultivations of peripheral blood by means of the BUDR/FPG technique in controls and in five patients with 45,X/46,X,i(Xq) mosaicism. No significant differences in the length of the cell cycle were observed between 45,X/46,X,i(Xq) and control 46,XX cells. The number of SCE on late i(Xq) was only nonsignificantly elevated (0.6 per i(Xq)) against the value expected on the basis of its relative length.     

45,X/46,XYq dic-Geschlechtschromosomenmosaik

Zusammenfassung Es wird über eine Patientin mit Kleinwuchs, Adipositas und sexuellem Infantilismus berichtet. Die Abklärung ergab ein 45,X/46,XYq dic-Mosaik. Es folgt eine Zusammenfassung der bis jetzt in der Literatur beschriebenen Fälle von Ydic. Das klinische Bild unterscheidet sich nicht wesentlich von jenem des 45,X/46,XY-Mosaiks. Anschließend werden die Zusammenhänge zwischen strukturellen Aberrationen des Y-Chromosoms und Phänotypus diskutiert.

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45,X/46,XYq dic-Sexchromosome mosaic

Summary This is the report on an obese girl with small stature and sexual infantilism. A 45,X/46,XYq dic mosaic was found in blood and fibroblast cultures. A summary is given of the cases so far reported in the literature. The clinical picture does not differ significantly from that of 45,X/46,XY cases. The relationship of phenotype and structural abnormalities of the Y chromosome is discussed.

     

A complex mosaicism 45,X/46,X,del(Xq)/46,X,idic(Xq) in a patient with secondary amenorrhea

A complex mosaicism involving the X chromosome was found in a 35-year-old female affected by secondary amenorrhea and short stature. Her karyotype was: 45,X[20]/46,X,del(X)(pter-->q26::qter)[15]/46,X,idic(X)(pter-->q26::q26-->pter)[9]. No cell contained both abnormal X chromosomes. This observation would suggest a possible mechanism underlying the formation of isodicentric chromosomes.     

Discordant growth pattern and ovarian function in monozygotic twins with 45,X/46,XX mosaicism

BACKGROUND: We report on phenotypically discordant female monozygotic twins with 45X/46,XX mosaicism in both lymphocytes and fibroblasts. RESULTS: At 11.5 years, twin A was prepubertal, her height was 126.8 cm (-3.15 SD), bone age (BA) 9.7 years (TW2), FSH 47 IU/l and IGF-I 280 ng/ml (-0.89 SD), but twin B was pubertal (P2, B3), her height was 143.4 cm (-0.92 SD), BA 13.6 years (TW2), FSH 3.4 IU/l and IGF-I 380 ng/ml (-0.21 SD). One year later, twin A had grown 11.1 cm due to growth hormone therapy and had IGF-I 1,400 ng/ml (+5.91 SD), whereas the growth velocity of twin B (no therapy) was 5.9 cm, IGF-I 540 ng/ml (+0.57 SD) and she started regular menstruation at 12.1 years. CONCLUSION: To our knowledge, this is the first report on monozygotic twins with Turner mosaicism in both lymphocytes and fibroblasts who developed a discordant phenotype probably due to an unequal distribution of the two cell lines in distinct tissues.     

Hae III restriction of DNA from three cases with nonfluorescent Y chromosomes (45XO/46XYnf)

Summary Hae III restriction patterns are reported in three cases with normal-sized but nonfluorescent Y chromosomes (XO/XYnf mosaics). The 3.4- and 2.1-kb fragment classes of reiterated Y chromosomal DNA were not present in the three cases. Mechanisms leading to these findings are discussed.     

A case of 46,XY/45,X/46,XX intersex

Summary A case of 46,XY/45,X/46,XX mosaicism in a phenotypic intersex is decribed in detail. A few relevant aspects, which emerge especially from the phenotypic and karyotypic analysis, are briefly commented upon.

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Zusammenfassung Es wird ein Fall von Mosaicismus 46,XY/45,X/46,XX beschrieben. Einige Aspekte, die aus der phänotypischen und karyotypischen Analyse des Patienten hervorgehen, sind kurz kommentiert.

     

45,X/46,SYq dic-Sexchromosome mosaic]

This is the report on an obese girl with small stature and sexual infantilism. A 45,X/46,XYq dic mosaic was found in blood and fibroblast cultures. A summary is given of the cases so far reported in the literature. The clinical picture does not differ significantly from that of 45,X/46,XY cases. The relationship of phenotype and structural abnormalities of the Y chromosome is discussed.     

Ring Y chromosome: 45,X/46,X,r(Y) chromosome mosaicism in a phenotypically normal male with azoospermia

Summary Chromosome analysis of lymphocytes in a phenotypically normal male with azoospermia showed a mosaicism 45,X/46,X,r(Y). Seven other cases from the literature are discussed.     

45,X/46,X,dic(Yq) mosaicism and mixed gonadal dysgenesis. Case report and review of the literature.

A 4 year 7 month-old boy with ambiguous genitalia, histological evidence of mixed gonadal dysgenesis, and 45,X/46,X,dic(Yq) mosaicism is reported. The identity of the dicentric Y chromosome was stablished by its typical fluorescent banding patterns and the presence of two centromeres demonstrated by C-band technique. A review of the literature yielded nine additional cases of mosaic 45,X/46,X,dic(Yq). Phenotypical and histological findings among these cases were compared, and the possible localization of the genes responsible for testicle induction and maturation is discussed.