Overrepresentation of pregnancies conceived by artificial reproductive technology in prenatally identified fetuses with Beckwith-Wiedemann syndrome.

OBJECTIVES: In vitro fertilization (IVF) has been linked to an increased risk for imprinting disorders in offspring. The data so far have predominantly been retrospective, comparing the rate of IVF conceptions in affected patients with controls. We describe a series of fetuses with omphalocele that were tested for Beckwith-Wiedemann syndrome (BWS) and subsequently ascertained as to whether pregnancies were conceived by assisted reproductive technologies (ART). METHODS: Fetuses were tested for BWS by Southern blot, PCR based methods, and methylation analysis to identify the imprinting status at primarily the IC2 locus, KCNQ1OT1, as well as IC1, H19/IGF-2. Some fetuses were also tested for uniparental disomy of chromosome 11p. RESULTS: We tested 301 fetuses with omphalocele for BWS. Forty samples were positive. Sixteen were from IVF pregnancies, for an overall rate of 40%. Such as high proportion of IVF pregnancies in a series of BWS-positive fetuses has not been described previously. Possible factors such as twinning and ascertainment bias are discussed. CONCLUSION: We found about a 20-fold overrepresentation of IVF cases in fetuses with BWS/omphalocele when compared with the rate of ART pregnancies in the USA (p < .0001). Our series provides support for an association of IVF and BWS. Patients should be counseled about these risks and made aware of the availability of prenatal diagnosis for detection.

A deletion 13q34/duplication 14q32.2-14q32.33 syndrome diagnosed 50 years after neonatal presentation as infantile hypercalcemia.

During infancy, this 50-year-old man with a previously undiagnosed multiple congenital anomalies/intellectual disability (MCA/MR) syndrome had grossly symptomatic hypercalcemia and was (briefly) thought to have Williams syndrome. Results of studies with the cytogenetic methods of the 1960s and 1970s were apparently normal. He matured late, but is high-functioning and healthy. Over 50 years he remained a diagnostic enigma. Thus, it came as a surprise when recent high-resolution banding methods showed an abnormality of the terminal portion of 13q, determined on array-comparative genomic hybridization to constitute an unbalanced chromosome rearrangement with a 0.35 Mb loss of 13q34-ter and 7.67 Mb gain of 14q32.2q32.33 translocated to 13q34. This apparently de novo genomic abnormality must be presumed as the cause of this previously undescribed MCA/MR syndrome which, however, may remain a private syndrome in this family. Williams syndrome was ruled out, and presently it is not possible to ascribe this patient's severely symptomatic infantile hypercalcemia to any gene on the deleted or duplicated chromosome segments. This "case" does underscore the importance of re-studying previously obscure but evidently genetic conditions, of long-term follow-up and documentation of natural history, and of providing, at last, a causal explanation to the family.

Androgenetic/biparental mosaicism in an infant with hepatic mesenchymal hamartoma and placental mesenchymal dysplasia.

Androgenetic/biparental mosaicism, in which a subset of cells has complete paternal uniparental disomy, is associated with placental mesenchymal dysplasia (PMD), which is compatible with fetal development, indicating that fetal organs could also have androgenetic/biparental mosaicism, but few cases of somatic mosaicism have been described. A hepatic mesenchymal hamartoma (HMH) was resected from an otherwise healthy, nondysmorphic, 11-month-old girl, whose prenatal development was complicated by PMD. Placenta, HMH, histologically normal liver, and other tissues were examined for androgenetic/biparental mosaicism by analysis of (1) polymorphic DNA microsatellite markers, (2) the methylation status of an imprinted gene, SNRPN, and (3) immunohistochemically detectable protein products of the imprinted genes p57KIP2 and PHLDA2. The patient's liver, HMH, and 1 placental sample demonstrated an increased ratio of paternal to maternal alleles, indicating androgenetic/biparental mosaicism. The androgenetic component comprised 26% to 60% of the cells. Other tissues, including a 2nd placental sample, white blood cells, umbilical cord, and abdominal fascia, had no detectable androgenetic component. Methylation analysis confirmed a relative excess of the paternally imprinted SNRPN homolog in the normal liver, HMH, and placenta. Placental p57KIP2 immunoreactivity was consistent with androgenetic/biparental mosaicism, but neither p57KIP2 nor PHLDA2 immunohistochemistry were informative for HMH, because neither antigen was detected in control liver samples. We report androgenetic/biparental mosaicism in nonplacental tissues of an infant with PMD and provide the 1st description of genome-wide paternal uniparental disomy in HMH. Androgenetic/biparental mosaicism appears to play a role in the pathogenesis of HMH and other somatic lesions, particularly those associated with PMD.

De novo isodicentric X chromosome: 46,X,idic(X)(q24), and summary of literature.

We describe a 12-year-old patient, the second live born prenatally ascertained patient in the literature, with a de novo isodicentric X chromosome, karyotype 46,X,idic(X)(q24), with normal growth and development and lack of dysmorphic features. Molecular and cytogenetic studies were performed to further characterize the isodicentric chromosome X behavior. Literature on isodicentric X chromosomes with various breakpoints on Xq is reviewed and summarized.

Dizygotic twin pregnancy conceived with assisted reproductive technology associated with chromosomal anomaly, imprinting disorder, and monochorionic placentation.

Assisted reproductive technology (ART) has now become a cornerstone of treatment for involuntary infertility. Recent studies have raised concern regarding potential associations between ART and chromosomal aneuploidy, imprinting anomalies, and monochorionic placentation in dizygotic (DZ) twins. We report a case of DZ twins conceived by ART in which all three problems coexist.

Recurrent adjacent-2 segregation of a familial t(14;21)(q11.2;q11.2): phenotypic comparison of two brothers and a paternal aunt inheriting the der(14).

A 14-year-old boy was referred for a genetics evaluation after high-resolution chromosome analysis showed a small amount of extra material in the proximal long arm of chromosome 21. Five years prior, his karyotype analysis was interpreted as normal with a variant chromosome 21. The patient has short palpebral fissures, strabismus, flat antihelices of the ears, long thumbs with bilaterally absent interphalangeal creases, proximal bilateral 3/4 syndactyly, small testes, hypotonia, mental retardation, and speech problems. He has significant depression and behavioral problems including hyperactivity, aggression, and impulsivity. His 8-year-old brother has more severe behavioral disturbances and depression, but less significant mental retardation. A paternal aunt has mental retardation, is unusually docile, and appears similar to our patient. Chromosome analysis and fluorescence in situ hybridization (FISH) whole chromosome paint of chromosome 21 showed that the patient's father carries a "cryptic" balanced translocation, 46,XY, t(14;21)(q11.2;q11.2), as does the patient's paternal grandmother. Uniparental disomy studies using seven informative polymorphic nucleotide repeat markers from 14q and 21q confirmed biparental inheritance of the number 14 and 21 chromosomes for each brother, and indicate that they and the paternal aunt, all of whom inherited the der(14), are monosomic for proximal 21q and trisomic for proximal 14q. These karyotypes arose through an adjacent-2 segregation in the father on two occasions, and from the paternal grandmother on one occasion. This family is an example of recurrent malsegregation with translocations involving the acrocentrics.

A child with Angelman syndrome and trisomy 13 findings due to associated paternal UPD 15 and segmental UPD 13.

A child with Angelman syndrome, cutis aplasia, cleft palate, and congenital microform cleft lip, born to a father with a Robertsonian translocation 13;15 is described. Molecular studies using polymorphic markers on chromosomes 15 and 13 showed paternal uniparental disomy (UPD) 15 and segmental UPD 13.

A case of segmental paternal isodisomy of chromosome 14.

Uniparental disomy of chromosome 14 (UPD 14) results in one of two distinct abnormal phenotypes, depending upon the parent of origin. This discordance may result from the reciprocal over-expression and/or under-expression of one or more imprinted genes. We report a case of segmental paternal isodisomy for chromosome 14 with features similar to those reported in other paternal disomy 14 cases. Microsatellite marker analysis revealed an apparent somatic recombination event in 14q12 leading to proximal biparental inheritance, but segmental paternal uniparental isodisomy distal to this site. Analysis of monochromosomal somatic cell hybrids containing either the paternally inherited or the maternally inherited chromosome 14 revealed no deletion of the maternally inherited chromosome 14 and demonstrated the presence of paternal sequences from D14S121 to the telomere on both chromosomes 14. Thus, the patient has paternal isodisomy for 14q12-14qter. Because the patient shows most of the features associated with paternal disomy 14, this supports the presence of the imprinted domain(s) distal to 14q12 and suggests that the proximal region of chromosome 14 does not contain imprinted genes that contribute significantly to the paternal UPD 14 phenotype.