Monosomy 8q: Prenatal diagnosis and autopsy findings

The autopsy findings of a fetus with deletion of the long arm of chromosome 8 are described. Many of the features are similar to those of the tricho-rhino-phalangeal syndromes, types I and II, which are associated with deletions on chromosome 8q24. Other findings in this case, such as total absence of the corpus callosum and intestinal malrotation, have not been described in these syndromes. Genes involved in the development of the latter malformations may reside in adjacent regions on the long arm of chromosome 8. An elevated serum level of beta human chorionic gonadotropin (βhCG) was found during pregnancy. This aberration should be included with other chromosomal disorders which may be detected by this test.     

Prenatal diagnosis of del(15)(q11q13)

A case of del(15)(q11q13) was detected in amniotic fluid cell cultures and confirmed by cordocentesis in a 27-year-old woman with a low maternal serum alpha-fetoprotein level. The fetus was shown to have a short femoral length on ultrasonography. This structural chromosome abnormality associated with the prenatal ultrasonographic findings and the morphological characteristics visualized after termination of pregnancy strongly suggest Prader-Willi syndrome.     

Prenatal diagnosis of mosaicism 46, XX/46, XX, −21, +t(21q21q)

Mosaicism for a structural chromosome abnormality in amniotic cell cultures indicative of true fetal mosaicism is a rare event. In addition to the laboratory findings the clinical interpretation for counselling in such cases is based on observation of the same abnormality in liveborns as well as previous experience with prenatal diagnosis of the same or similar abnormalities. We report here the prenatal diagnos is of 46,XX/46,XX,−21,+t(21q21q) which was confirmed in fetal skin cell and amnion cell cultures.     

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.     

A rare case of de novo distal 19q trisomy prenatally diagnosed

We present a case of de novo trisomy of distal 19q diagnosed prenatally by cytogenetics and FISH analysis. The autopsy performed after termination of the pregnancy showed major internal and external malformations that are associated with this chromosome abnormality. Copyright © 2004 John Wiley & Sons, Ltd.     

Mosaic Isochromosome 20q found on amniocentesis with normal outcome

A case of mosaic isochromosome 20q found on amniocentesis is described. A normal male infant was subsequently born.     

46,XY,dup(10q) in direct CVS preparation and mosaic 48,XXXY,dup(10q) in CVS long-term culture and fetal tissue

Chorionic villus sampling (CVS) was performed on a 40-year-old woman at 9 1/2 menstrual weeks because of advanced maternal age. The direct preparation showed 46,XY,dup(10)(q11.2q23.2). CVS long-term culture and fetal tissue revealed a rare additional abnormality: 48,XXXY,dup(10)(q11.2q23.2). This abnormality represented the major cell line (>85 per cent in 691 cells) in an (XY)/XXY/XXXY/(XXXXY) mosaic (all cell lines presumably bearing the dup(10q); the presence of XY and XXXXY cell lines is uncertain). To our knowledge, this is the first report of trisomy 10q11-q23 and of prenatally detected 48,XXXY in chorionic villi. The mosaic could have resulted from early post-zygotic non-disjunctions in a 46,XY,dup(10q) or 47,XXY,dup(10q) zygote. The results from DNA studies of four polymorphisms, mapped to Xp and Xq, support this theory. The literature on prenatally detected cases with sex chromosome tetrasomy and pentasomy and those with additional autosomal abnormalities is reviewed. The reported case underlines the problem of false-negative findings when only direct CVS preparations are karyotyped.     

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 holoprosencephaly in two fetuses with der (7)t(1;7)(q32;q32)pat inherited from the father with double translocations

The presence of two independent translocations in one person is rare. Herein, we report the prenatal diagnosis of two sibling fetuses with holoprosencephaly, whose father is a carrier of double translocations. The karyotype of the father is 46,XY, t(1;7) (q32;q32), t(14,15) (q32.1;q26.3). The two fetuses had variable facial dysmorphisms and identical cytogenetic abnormality—a derivative (7) t(1;7) (q32;q32) inherited from the father. The proband 1 showed a small mouth, a single median eye and a proboscis above the eye, while the proband 2 showed hypotelorism, a flat nose, cleft lip and cleft palate. Both fetuses also had alobar holoprosencephaly. Haploinsufficiency of the sonic hedgehog gene at 7q36 does account for the occurrence of holoprosencephaly in the two fetuses with a deletion of distal 7q (7q32 → qter). Copyright © 2003 John Wiley & Sons, Ltd.     

Interrupted aortic arch type A with 22q11 deletion: prenatal detection of an unusual association

Interrupted aortic arch is a rare, severe congenital heart defect subdivided into three types, A, B and C, according to the site of interruption. Type C is by far the least common form of interrupted aortic arch (less than 5% of cases), type A is commonly an isolated defect whereas type B is frequently associated with 22q11 deletion. Differentiation of interrupted aortic arch type A from type B by prenatal echocardiography is possible but difficult; it needs to be done on the basis of observation of reliable morphological indicators which point to the correct diagnosis. Here we report the first case of prenatal diagnosis of interrupted aortic arch type A associated with 22q11 deletion. The significance of this association is not yet clear, since 22q11 genes mainly affect embryonic cardiovascular morphogenesis of those regions whose development is critically dependent on neural crest cell migration and function, affected in type B defect but not in type A. Copyright © 2002 John Wiley & Sons, Ltd.