Prenatal diagnosis of a fetus with pure partial trisomy 1q32-44 due to a familial balanced rearrangement

We diagnosed a pure partial trisomy of the long arm of chromosome 1 in a fetus with multiple malformations detected prenatally. The father was a carrier of a balanced rearrangement involving 46,XY,inv(1)(qter→p36::q32→qter::p36→q32). The fetus had preaxial polydactyly, low-set ears, macrocephaly, a prominent forehead, a broad and flat nasal bridge, a small mouth, an arched palate, micrognathia and unilateral renal agenesis. The couple had previously an infant with the same phenotypic abnormalities. The aberration was initially detected on amniocentesis with GTG banding and was confirmed by fluorescence in situ hybridization (FISH). Our case and other published pure trisomy 1q32-44 cases showed similarities, which allowed the further delineation of the trisomy 1q syndrome. Copyright © 2002 John Wiley & Sons, Ltd.     

Prenatal diagnosis of monosomy 4p14→pter and trisomy 11q25→qter: clinical presentations and outcomes

We present the case of a pregnant woman with low free β-HCG in maternal serum Down syndrome screening that led to prenatal diagnosis of a fetus with 46,XY,der(4)t(4;11)(p14; q25). This chromosomal aneuploidy resulted from unbalanced segregation of a paternal balanced translocation, t(4;11)(p14;q25). Prenatal ultrasound revealed intrauterine growth restriction, cleft lip and palate, a thick nuchal fold, a single umbilical artery, and pyelectasis. Array-based comparative genomic hybridization and short tandem repeat markers further located the exact breakpoint of translocation. The woman had her pregnancy terminated at 23 weeks of gestational age. The proband had general appearance of Wolf–Hirschhorn syndrome and some unique findings, including single umbilical artery, severe immunoglobulin deficiency, scalp defect, and underlying bony defect. Our case underscores the importance of fetal karyotyping when low maternal serum free β-HCG is found. It also adds information on the fetal presentations of monosomy 4p14→pter and trisomy 11q25→qter. Copyright © 2005 John Wiley & Sons, Ltd.     

Prenatal diagnosis and prenatal imaging features of fetal monosomy 1p36

Deletion of the distal end of the short arm of chromosome 1 (1p36) is thought to be a common terminal chromosomal deletion. However, few cases prospectively diagnosed prenatally have been reported. In this case, prenatal ultrasound at 21 weeks of gestation noted the fetus to have mild ventriculomegaly (Vhanterior = 11 mm and Vhposterior = 12 mm) and increased nuchal edema (6 mm). Maternal serum α-fetoprotein was normal unlike in a majority of previously described cases. The prenatal ultrasound features were further clarified with fetal MRI. Chromosome analysis following amniocentesis demonstrated a 1p36 deletion, which was confirmed by fluorescence in situ hybridization (FISH). The syndrome associated with 1p36 deletion is well described in infants and is characterized by typical facial features (prominent forehead, straight eyebrows. deep-set eyes, flat nasal bridge and a pointed chin). Other associated features are neurodevelopmental delay, seizures, cardiomyopathy and neurosensory hearing impairment. This case supplements our knowledge of the prenatal features of 1p36. Identification of this deletion by direct chromosomal analysis can be technically difficult and vigilance is required to improve diagnosis. FISH analysis is an important diagnostic adjunct where the diagnosis is suspected following classical G-banding techniques. However, in this chromosomal anomaly there remain few characteristic prenatal signs that are readily diagnosed with prenatal imaging. Copyright © 2007 John Wiley & Sons, Ltd.     

Distal partial trisomy 1q: report of two cases and a review of the literature

We report on two cases with partial trisomy 1q syndrome. One case was a mid-trimester fetus with multiple malformations that was prenatally diagnosed with a de novo distal partial trisomy 1q. Prenatal ultrasound at 24th gestational week demonstrated the presence of cleft lip and palate, increased biparietal diameter and decreased abdominal circumference. Cytogenetic analysis (GTG banding) and subsequent fluorescence in situ hybridization (FISH) using whole chromosome paint 1 and multicolor banding (MCB) demonstrated an aberrant karyotype 46,XY,dup(1)(q31q43∼44). The second case was a newborn male infant with multiple congenital malformations. He had a derivative chromosome 18 as a result of a maternal insertion involving chromosomes 1 and 18. Further analyses including MCB showed his karyotype as 46,XY,ins(18;1)(q22;q23q31.1∼32). The present cases and a review of the literature suggest that partial trisomy of the long arm of chromosome 1 is a distinct clinical entity. Copyright © 2007 John Wiley & Sons, Ltd.     

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 overgrowth and mosaic trisomy 15q25-qter including the IGF1 receptor gene

Overgrowth is rarely associated with chromosomal imbalances. Here, we report on a male foetus presenting with overgrowth and additional material on the short arm of one of the chromosome 15 in 12% of lymphocytes and 50% of amniotic cells. Parents' karyotypes were normal, indicating a de novo origin for this unbalanced rearrangement. Complementary studies using cytogenetic and FISH studies showed that this additional material resulted in a 15q25-qter trisomy and confirmed the presence of three copies of the insulin-like growth factor 1 receptor (IGF1R) gene, included in the trisomic region. Autopsy performed after termination of pregnancy revealed isolated overgrowth and absence of visceral malformations. The possible mechanisms and origins for the formation of this mosaic pure trisomy are complex. The present observation emphasises the hypothesis that the overgrowth phenotype, frequently reported in patients with trisomy including the 15q26 region, might be causally related to a dosage effect of the IGF1R gene, as well as the importance of chromosome analysis in patients with overgrowth. It also confirms that the overgrowth is of prenatal onset in those observations. Copyright © 2004 John Wiley & Sons, Ltd.     

Syndromic encephalocele in a fetal case with a 1p35-pter deletion and a 14q32-qter duplication inherited from a maternal balanced translocation

Occipital encephalocele belongs to the family of neural tube defects, which occur in one among 2000 to 5000 live births. Syndromic encephaloceles include Meckel–Gruber syndrome and various chromosomal abnormalities. We report on a fetal case (13 WG) with bilateral cleft lip and palate, choanal atresia, occipital encephalocele, bilateral club feet, bilateral multicystic kidneys, enlarged bladder and urethral atresia. The fetal chromosome analysis showed a maternally inherited unbalanced translocation between the short arm of chromosome 1 and the long arm of chromosome 14, resulting in 1p35-pter deletion and 14q32-qter duplication (46,XY,der(1),t(1;14)(p35;q32)). Since the chromosomal breakpoints have not previously been implicated in syndromic encephalocele, this observation is of interest for the identification of other genes responsible for occipital encephalocele. Copyright © 2007 John Wiley & Sons, Ltd.     

Prenatal diagnosis of partial monosomy 18p(18p11.2→pter) and trisomy 21q(21q22.3→qter) with alobar holoprosencephaly and premaxillary agenesis

A prenatal diagnosis of partial monosomy 18p(18p11.2→pter) and trisomy 21q(21q22.3→qter) in a fetus with alobar holoprosencephaly (HPE) and premaxillary agenesis (PMA) but without the classical Down syndrome phenotype is reported. A 27-year-old primigravida woman was referred for genetic counselling at 21 weeks' gestation due to sonographic findings of craniofacial abnormalities. Level II ultrasonograms manifested alobar HPE and median orofacial cleft. Cytogenetic analysis and fluorescence in situ hybridization (FISH) on cells obtained from amniocentesis revealed partial monosomy 18p and a cryptic duplication of 21q,46,XY,der(18)t(18;21)(p11.2;q22.3), resulting from a maternal t(18;21) reciprocal translocation. The breakpoints were ascertained by molecular genetic analysis. The pregnancy was terminated. Autopsy showed alobar HPE with PMA, pituitary dysplasia, clinodactyly and classical 18p deletion phenotype but without the presence of major typical phenotypic features of Down syndrome. The phenotype of this antenatally diagnosed case is compared with those observed in six previously reported cases with monosomy 18p due to 18;21 translocation. The present study is the first report of concomitant deletion of HPE critical region of chromosome 18p11.3 and cryptic duplication of a small segment of distal chromosome 21q22.3 outside Down syndrome critical region. The present study shows that cytogenetic analyses are important in detecting chromosomal aberrations in pregnancies with prenatally detected craniofacial abnormalities, and adjunctive molecular investigations are useful in elucidating the genetic pathogenesis of dysmorphism. Copyright © 2001 John Wiley & Sons, Ltd.     

Prenatal diagnosis of an isochromosome 5p in a fetus with increased nuchal translucency thickness and pulmonary atresia with hypoplastic right heart at 14 weeks

We report on a fetus presenting with increased nuchal translucency at 11 weeks' gestation, suggesting cystic hygroma. Chorion villous sampling was performed, and cytogenetic analysis revealed a supernumerary isochromosome 5p leading to tetrasomy 5p: 47,XX,+ i(5p)[7]/46,XX[5] after short-term culture and 47,XX,+ i(5p)[20] after long-term culture. Subsequent targeted sonographic follow-up at 12 and 14 weeks revealed further increase of the NT to 6.4 mm and the additional presence of a congenital heart defect (pulmonary atresia with intact ventricular septum). Termination of pregnancy was performed, and the heart defect was confirmed. Isochromosome 5p was found in varying proportions in all examined organs. Only a few cases of mosaic tetrasomy 5p have been reported in the literature, and recent reports on prenatally detected isochromosome 5p showed a possible relationship to increased nuchal translucency in some cases and also a possible role of confined mosaicism in others. Whereas cases with confined mosaicism did not show suspicious signs on ultrasound, true mosaicism conversely showed increased nuchal thickness as well as structural abnormalities. This is the first report on the association of a cardiac defect with this chromosome aberration. Copyright © 2004 John Wiley & Sons, Ltd.     

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.     

Prenatal diagnosis of mosaic 4p – in a fetus with trisomy 21

Mosaicism for the Wolf-Hirschhorn syndrome, del(4)(p16), is extremely rare and has not been reported in association with a numerical chromosome abnormality. We report the prenatal diagnosis of mosaic del(4)(p16) and non-mosaic trisomy 21 in a 16-week female fetus. The pregnancy ended in spontaneous abortion at 34 weeks secondary to fetal demise. The fetus had features of both 4p – and trisomy 21.