Prenatal diagnosis of 45,X/46,XY mosaicism in a fetus with asymmetric gonadal dysgenesis

An 18 week abortus had been prenatally diagnosed as a 45,X/46,XY mosaic. The fetus was a phenotypic male with glandular hypospadias, a horseshoe kidney and asymmetric gonadal dysgenesis. This case represents a rare instance of prenatally diagnosed 45,X/46,XY mosaicism with an abnormal phenotype.     

Prenatal diagnosis of fragile X in a heterozygous female fetus and postnatal follow-up

An apparently normal female infant was born after the prenatal diagnosis of fragile Xq27×28 present in about 4 per cent of amniocytes. The mildly retarded mother had been found in early pregnancy to be heterozygous for fragile X. The child, now 9 months old. showed about the same level of fragile X expression as her mother. Variations in the proportion of cells with fragile X appeared to be related to cell type and laboratory techniques. The infant's growth and development have been normal. Different techniques to induce or increase the expression of fragile X are discussed.     

Prenatal diagnosis of a small supernumerary,XIST-negative,mosaic ring X chromosome identified by fluorescence in situ hybridization in an abnormal male fetus

Marker or ring X [r(X)] chromosomes of varying size are often found in patients with Turner syndrome. Patients with very small r(X) chromosomes that did not include the X-inactivation locus (XIST) have been described with a more severe phenotype. Small r(X) chromosomes are rare in males and there are only five previous reports of such cases. We report the identification of a small supernumerary X chromosome in an abnormal male fetus. Cytogenetic analysis from chorionic villus sampling was performed because of fetal nuchal translucency thickness and it showed mosaicism 46,XY/47,XY,+r(X)/48,XY,+r(X),+r(X). Fluorescence in situ hybridizations (FISH) showed the marker to be of X-chromosome origin and not to contain the XIST locus. Additional specific probes showed that the r(X) included a euchromatic region in proximal Xq. At 20 weeks gestation, a second ultrasound examination revealed cerebral abnormalities. After genetic counselling, the pregnancy was terminated. The fetus we describe is the first male with a mosaic XIST-negative r(X) chromosome identified at prenatal diagnosis. The phenotype we observed was probably the result of functional disomy of the genes in the r(X) chromosome, secondary to loss of the XIST locus. Copyright © 2003 John Wiley & Sons, Ltd.     

Prenatal diagnosis of the fragile X syndrome using fetal blood and amniotic fluid

Nineteen pregnancies at risk for the Martin–Bell syndrome have been monitored during the second trimester for the presence of the fragile Xq27. Of the 19 potential carrier mothers, 14 showed the presence of the fragile X in their lymphocytes at a level of 4 per cent or above. As one was a twin pregnancy, fetal blood was obtained at fetoscopy from 20 fetuses and amniotic fluid obtained simultaneously from 19 of them. Of the 20 fetuses, 18 were males (including both of the twins) and two were females. Of these 18 males, seven were found to carry the fragile Xq27 in lymphocytes and subsequently six of the seven were terminated. The diagnosis was confirmed in five of the six terminated fetuses (the sixth case was a patient whose pregnancy was terminated abroad) and also in a full-term male baby. Five of the seven males without the marker X who came to term had their karyotypes confirmed post natally. Of the two female fetuses one was found to be a carrier of the fragile X and the other was not. Both babies had full-term deliveries and both had their karyotypes confirmed post natally. In some cases the diagnosis made in fetal lymphocytes was confirmed later in amniocytes.     

Prenatal diagnosis of a fetus with terminal deletion of chromosome 1 (q41)

Many authors have suggested that individuals affected by a terminal 1q deletion display a phenotypically definable and recognizable syndrome. In all of the 27 cases reported to date, the breakpoints were at band q42 or distally to it. To our knowledge, we report the first case of a terminal 1q41 deletion. Diagnosis was made prenatally by amniocentesis, following ultrasonographic diagnosis of omphalocele, cerebral ventriculomegaly, and increased nuchal fold thickness in a 19-week female fetus. Multiple facial and extremity features were consistent with the proposed distal 1q deletion syndrome; omphalocele, however, has not been reported previously. The absence of liver herniation into the omphalocele sac in this case supports the previously reported association of this finding with chromosomal anomalies.     

Prenatal diagnosis of a fetus with partial monosomy 7(q34→qter) and partial trisomy 18(q21→qter)

Ultrasound examination of a 31-year-old woman at 27 weeks' gestation revealed fetal growth retardation, a bilateral cleft lip and palate, and the absence of median cerebral structures. Chromosome analysis after cordocentesis showed an abnormal karyotype with a structural abnormality of the long arm of chromosome 7: 46,XX,—7,+der(7), t(7;18) (q34;q21.3)mat. The pregnancy was terminated at week 29. The ultrasound findings were confirmed by post-mortem examination, which also revealed a semilobar holoprosencephaly.     

Prenatal diagnosis of an extra der(4) resulting from a complex maternal chromosome translocation

We report the prenatal diagnosis of an extra der(4) resulting from 4:2 malsegregation of a maternal balanced complex translocation involving chromosomes 4, 10, and 11. The woman was referred for amniocentesis because of recurrent miscarriages. Fluorescence in situ hybridization was performed in order to characterize the complex chromosome rearrangement. Following genetic counselling, the couple decided to terminate the pregnancy. Copyright © 2004 John Wiley & Sons, Ltd.     

Prenatal diagnosis of the fragile X using thymidine induction

Eleven pregnancies in ten patients at risk for the fragile X were monitored by amniocentesis or chorion villus biopsy and induction of the fragile site using thymidine, methotrexate and FUdR. Three female fetuses and one male fetus were found to have the fragile X. The results obtained using thymidine induction were superior to those using methotrexate induction and probably better than those obtained using FUdR induction.     

Prenatal investigation of a 45,X/46,X,r(?) karyotype in amniocytes using fluorescence in situ hybridization with an X-centromeric probe

The karyotype of cultured amniotic fluid cells obtained on the indication of advanced maternal age was shown to be a mosaic 45,X/46,X,r(?). The small size and banding pattern made it difficult to determine whether the ring was derived from and X or a Y chromosome, or even from an autosome. By using an X-centromeric probe and fluorescence in situ hybridization (FISH), we demonstrated the ring to have an X centromere. Thus, a more complete genetic counselling was possible. This confirms the usefulness of FISH in identifying and characterizing this and other chromosome rearrangements in prenatal diagnosis.     

Female pseudohermaphroditism in a fetus with a deletion 9(q22.2q31.1)

Interstitial deletions of chromosomal region 9q are rarely seen. We report the first prenatal diagnosis of a de novo interstitial deletion 9q. The fetus was karyotyped for intrauterine growth retardation (IUGR). Conventional and molecular cytogenetics showed female karyotype with a de novo deletion of the chromosomal region 9(q22.2q31.1) leading to a partial monosomy 9q. At autopsy, the fetus showed growth retardation, dysmorphy, and a female pseudohermaphroditism. These results suggest that a gene(s) for genital development reside in chromosomal region 9q22.2q31.1. Copyright © 2002 John Wiley & Sons, Ltd.     

Prenatal diagnosis of complete sole trisomy 1q

The prenatal diagnosis of a complete trisomy of the long arm of chromosome 1 is reported. Major ultrasound findings included: nuchal thickening, bi-temporal narrowing, a single choroid plexus cyst, andmild ventriculomegaly. There was a mass in the chest and abdomen, pleural effusion, ascites and a hyperechoic bowel. Skin edema was present. The fetus died at 26 weeks' gestation. A literature review is presented of 17 de novo and two inherited cases with only trisomy 1q. Of note is the fact that 3/5 prenatally detected 1q trisomies have teratomas. A review of the literature reveals a dismal outcome fortrisomy 1q cases if the duplication involves bands 1q25→q32. Copyright © 2001 John Wiley & Sons, Ltd.     

Prenatal diagnosis and outcomes of five cases of mosaicism for an isochromosome of 20q

Five cases of mosaicism for an isochromosome of 20q have been detected from a total of 50 000 cases analysed for prenatal diagnosis by amniocentesis. Karyotypes were designated mos 46,X_/46,X_,i(20q). In all cases, the abnormal cell line was detected in more than one primary culture, thus fulfilling the criterion for true (level III) mosaicism. Indications for prenatal diagnosis were parental anxiety (two cases), low maternal serum alpha-fetoprotein (AFP) (two cases), and high maternal serum AFP (one case). Level II ultrasounds on all five fetuses were normal, and the abnormal cell line was never detected in fetal blood and/or cord blood. All five pregnancies were continued and had normal outcomes, with birth weights ranging from 2.4 to 3.8 kg. The development of all five children has been normal, with the oldest child in the study now 4 years of age. We suggest that the abnormal cell line in each case was of extrafetal origin, and that this may be one of the more common examples of this phenomenon, occurring in approximately 1/10000 prenatal diagnoses. Mosaicism i(20q) may have been missed in the past because of the higher resolution necessary to detect this subtle change.     

Prenatal diagnosis of a fetus with androgen insensitivity syndrome (AIS)

Objective The aim of this study is to describe a fetus with androgen insensitivity syndrome diagnosed at mid-second trimester. Case and Methods Nuchal translucency was measured thick and double test was found higher. The patient referred to our center at 16^th weeks of gestation. Fetal ultrasound examination and amniocentesis was performed. Results The nuchal translucency (NT) of fetus in present pregnancy was measured approximately 10 mm at 13 weeks and Down syndrome risk was calculated 1 in 10 by double test. On ultrasound examination; thick nuchal fold (NF) and short fetal limbs were found, and the fetus was seen a female and amniocentesis was performed. Three weeks later the fetal karyotype was reported normal as 46,XY. Thereupon the fetus reexamined for 2D and 4D ultrasound, and confirmed previous findings. The fetus was terminated at 19^th weeks and seen a female phenotype. The fetal gonads removed in abdomen and testicles confirmed histopatologically. Conclusion In generally, diagnosis of AIS is most made postnatally. This is the second case in English literature, which diagnosed mid-second trimester. In this situation, the fetus with thick NT/NF and short limbs may be AIS, therefore appearance of fetal sex on ultrasound should be compared with genetic sex Copyright © 2007 John Wiley & Sons, Ltd.     

Pregnancy outcome following prenatal diagnosis of an isodicentric X chromosome: first case report

An isodicentric X chromosome, idic (X)(q27) was found in a female fetus during cytogenetic studies performed on amniotic cells due to advanced maternal age. No mosaicism was observed. Although segmental inversion duplications have been described for several other chromosomes, isodicentric chromosomes are reported only for gonosomes. Genetic counselling was based on ultrasound findings, cytogenetic replication studies and published cases of X chromosomes duplications ascertained pre- and postnatally. The pregnancy resulted in the birth of a healthy female infant. Copyright © 2002 John Wiley & Sons, Ltd.     

Prenatal diagnosis of 49,XXXYY

The first prenatally diagnosed case of 49,XXXYY is reported. The pathological findings of the fetus included bilateral clinodactyly, decreased carrying angles (OO), and hypertelorism, slightly low set ears and mildly prominent forehead. A minimum of two independent non- disjunctional events are postulated for this polysomy to arise.