Intrauterine growth retardation associated with precocious puberty and sertoli cell hyperplasia.

The original description of patients with Russell-Silver syndrome included precocious puberty, the mechanism of which was unclear. We describe a child with a Russell-Silver syndrome-like phenotype who presented with precocious puberty that was associated with hyperplasia of the Sertoli cells. The patient was found to have an immature cryptorchid testicle; hyperplastic Sertoli cells were also aneuploid carrying trisomy 8. This chromosomal abnormality was present in Sertoli cells only and could not be detected in peripheral lymphocytes, tunica vaginalis, or other, normal, testicular tissue. Sertoli cells in culture showed excess aromatization providing an explanation for the rapid advancement of the patient's bone age. We conclude that in a patient with a Russell-Silver syndrome-like phenotype, Sertoli cell hyperplasia was associated with somatic trisomy 8, increased aromatization, and gonadotropin-independent precocious puberty.

TGIF Mutations in Human Holoprosencephaly: Correlation between Genotype and Phenotype.

Holoprosencephaly (HPE), which results from failed or incomplete midline forebrain division early in gestation, is the most common forebrain malformation. The etiology of HPE is complex and multifactorial. To date, at least 12 HPE-associated genes have been identified, including TGIF (transforming growth factor beta-induced factor), located on chromosome 18p11.3. TGIF encodes a transcriptional repressor of retinoid responses involved in TGF-ß signaling regulation, including Nodal signaling. TGIF mutations are reported in approximately 1-2% of patients with non-syndromic, non-chromosomal HPE. We combined data from our comprehensive studies of HPE with a literature search for all individuals with HPE and evidence of mutations affecting TGIF in order to establish the genotypic and phenotypic range. We describe 2 groups of patients: 34 with intragenic mutations and 21 with deletions of TGIF. These individuals, which were ascertained from our research group, in collaboration with other centers, and through a literature search, include 38 probands and 17 mutation-positive relatives. The majority of intragenic mutations occur in the TGIF homeodomain. Patients with mutations affecting TGIFrecapitulate the entire phenotypic spectrum observed in non-chromosomal, non-syndromic HPE. We identified a statistically significant difference between the 2 groups with respect to inheritance, as TGIF deletions were more likely to be de novo in comparison to TGIF mutations (χ(2) ((2)) = 6.97, p(permutated) = 0.0356). In addition, patients with TGIF deletions were also found to more commonly present with manifestations beyond the craniofacial and neuroanatomical features associated with HPE (p = 0.0030). These findings highlight differences in patients with intragenic mutations versus deletions affecting TGIF, and draw attention to the homeodomain region, which appears to be particularly relevant to HPE. These results may be useful for genetic counseling of affected patients.

Prenatal diagnosis of supernumerary ring chromosome 1: case report and review of the literature.

A supernumerary ring chromosome was found on amniocentesis performed for advanced maternal age. A review of the literature found 34 reports of supernumerary ring chromosome I which are compared to our case.

Patient decisions regarding prenatal aneuploid fluorescence in situ hybridization results.

OBJECTIVE: To determine an appropriate risk cut-off to offer prenatal aneuploid FISH, and if FISH results affect patient decisions regarding pregnancy management. METHOD: Retrospective evaluation of 707 patients presenting for diagnostic prenatal testing. Studied parameters included gestational age, indication for testing, aneuploid risk, procedure performed, FISH (whether offered, requested, and/or performed), result turn-around time, karyotype results, decision after obtaining results, and the timing of that decision. Patients who were offered FISH were compared to those not offered FISH (student T-test). RESULTS: Twenty-five clinically significant abnormalities were detected by karyotype and/or FISH analysis. Thirteen out of 17 patients electing pregnancy interruption had FISH performed. There were no differences between the group that interrupted following FISH (n=7) and the group that interrupted following final karyotype results (n=6). Turn-around times for those abnormal samples with FISH testing was significantly shorter than for those without FISH testing (p=0.02). Risk thresholds of >or=0.5%, >or=1%, >or=2%, or >or=3%, would detect 92%, 84%, 48%, and 32% of the clinically significant anomalies with 663, 317, 118, and 66 FISH analyses performed, respectively. CONCLUSION: Acting on FISH results alone afforded a significantly shorter interval between test and pregnancy interruption. A risk cut-off >or=1% appears to optimize the detection rate and the yield of abnormal results.

Anisomastia associated with interstitial duplication of chromosome 16, mental retardation, obesity, dysmorphic facies, and digital anomalies: molecular mapping of a new syndrome by fluorescent in situ hybridization and microsatellites to 16q13 (D16S419-D16S503).

Anisomastia is a common problem among developing adolescent girls. We recently evaluated a 22-yr-old female patient who had severe anisomastia (which had been repaired by surgery), associated with moderate to severe mental retardation, a stocky body habitus with mild obesity, dysmorphic facies (prominent, upslanting palpebral fissures, beaked nose, and a prominent philtrum), webbed neck, low hairline, and severe bilateral clinodactyly of the third, fourth, and fifth fingers with acral (but not large joint) flexion contractures. A peripheral blood high resolution karyotype revealed additional chromosomal material within the long arm of chromosome 16. Densitometric analysis of amplified polymorphic sequence-tagged sites (STS) mapping to 16q suggested that the duplication is defined by the noninvolved markers D16S419 [16q12-cen, 66 centimorgan (cM) from 16p terminus] and D16S421 (16q13-q21, 84.4 cM), encompassing a maximum of 18.4 cM of genetic distance. The STS analysis showed that the duplication was on the maternally derived chromosome 16, resulting in two maternal (and one paternal) copies of that region of chromosome 16. The location was further confirmed by bacterial artificial chromosomes (BACs) that were obtained from a commercially available library, labeled, and used for fluorescence in situ hybridization. The BACs containing STSs D16S408, D16S3137, and D16S3032 (markers that correspond to 16q13) showed two regions of hybridization, indicating that these sites were duplicated, whereas a BAC containing the STS D16S512 (which corresponds to 16q21-q22) revealed one hybridization signal per 16q, indicating that the corresponding region was not involved in the duplication. The distance between the probe signals suggested a tandem duplication. We conclude that even though trisomy 16 is the most common autosomal trisomy in spontaneous abortions, few patients with unbalanced chromosome 16 abnormalities survive to adulthood; in this report we describe one such patient with an interstitial chromosome 16 duplication (at 16q13), who had a specific phenotype associated with abnormal breast size. There are clinical similarities between this patient and patients with other 16q abnormalities, although the breast findings were unique. Molecular cytogenetics, including fluorescence in situ hybridization and densitometric analysis of amplified STSs, provided useful tools for the precise mapping of the syndrome to 16q13, where the gene(s) responsible for this phenotype might be localized.

Trisomy 7p resulting from 7p15;9p24 translocation: report of a new case and review of associated medical complications.

The authors report on a young girl with generalized developmental deficits originally thought to be caused by an unusual reaction to DPT vaccination. At the age of 4(1/2) years, chromosome analysis showed that the terminus of the short arm of chromosome 9 had extra material believed to originate from 7p terminus, thus she was considered to be trisomic for a segment of 7p and monosomic for a small portion of 9p [46,XX,der (9), t(7;9)(p15;p24)]. Ten years later, molecular cytogenetic testing using fluorescence in situ hybridization (FISH) confirmed that the extra chromosomal material represented partial trisomy 7p. The proposita had a high and large forehead, hypertelorism, and broad nasal bridge, findings seen in most individuals with trisomy 7p. Long-term follow-up showed the presence of hypothyroidism, obesity, and cerebral palsy. A review of all published cases of trisomy 7p with focus on associated complications suggests a well-defined pattern of abnormalities characterized by musculoskeletal, cardiovascular, neurological, genital, and ocular abnormalities in decreasing frequency. At least one-third of affected individuals died in infancy and close to half had severe mental retardation. FISH was essential in the confirmation of the cytogenetic abnormality and further delineation of the chromosomal disorder.

Interstitial deletion of 4p15.32p16.3 in a boy with minor anomalies, hearing loss, borderline intelligence, and oligodontia.

We describe an 11-year-old boy of Saudi origin with an interstitial deletion in the short arm of chromosome 4 (p15.32p16.3) as determined by G-banding and fluorescent in situ hybridization. His clinical manifestations were similar but not identical to previously reported cases of interstitial deletion in the same chromosomal region, and were not those associated with Wolf-Hirschhorn syndrome. The boy had normal facial characteristics, short stature, minor anomalies of hands and feet, amblyopia of the right eye, bilateral hearing loss, and hypotonia. On developmental testing, he had borderline intelligence, with a severe sensory integration and motor planning disorder, and severe deficits in the communication domain. In addition, he had severe oligodontia affecting his secondary dentition. This finding supports the presence of one or more genes involved in dentition in this chromosomal region.

Risk of abnormal triple screen for Down syndrome is significantly higher in patients with female fetuses.

Previous studies have shown that mid-trimester maternal serum alpha-fetoprotein (AFP) levels are significantly higher and human chorionic gonadotrophin (hCG) levels significantly lower in women with male compared with female fetuses. We have evaluated whether triple-screen criteria are more likely to identify women with female fetuses as at risk for Down syndrome. From the Georgetown University genetics database we obtained the absolute values and corresponding multiples of the median (MoM) for AFP, hCG and unconjugated oestriol (uE3) in singleton gestations for the period database November 1992 July 1996. A Down syndrome risk of 1/270 or greater at mid-trimester was considered as high risk. A total of 977 patients with triple screen and outcome information were identified, including 502 female and 475 male fetuses. Patients with female fetuses were significantly more likely to have lower serum AFP (p=0.003) and a positive triple screen for Down syndrome (72 (14 per cent) versus 45 (9 per cent), p<0.02) than those with male fetuses. The gestational age at triple screen, maternal serum hCG and uE3, race and diabetes were not significantly different between the two groups. Since Down syndrome is less common in female than male fetuses, and the rates of female and male Down syndrome fetuses detected by triple screen and subsequent amniocentesis are not significantly different, the excess of positive mid-trimester maternal serum triple screen in women with female fetuses is likely due to false-positive results.

Cytogenetic analysis using telemedicine consultation: an improved means of providing expert cross-coverage.

PURPOSE: We used telemedicine in providing cross-coverage for a clinical cytogenetics laboratory. A genetic teleconsultation system was used to provide expert cross-coverage for a laboratory in a neighboring metropolitan region for a 6 month period while the usual provider of these services was on military reserve duty. METHODS: The teleconsultation system was a commercially available Perceptive Scientific Instruments (PSI) workstation. Five hundred thirty-nine cytogenetic cases were performed during the study period in the home laboratory in Baltimore, Maryland. RESULTS: Karyotypes and supporting metaphase spreads were transmitted by modem to the covering director, whereas work sheets and reports were faxed. Physical transfer of data was not necessary, and turn-around-time was not increased. CONCLUSION: This ability to employ a remote part time director has significant benefits for the laboratory with an absentee director for short or even extended periods of time. We conclude that the use of telemedicine in clinical cytogenetics proved to be an efficient and a cost effective means of providing genetics services to a region during a time of cross-coverage need.

Detection of mosaicism in amniotic fluid cultures: a CYTO2000 collaborative study.

PURPOSE: To evaluate the assumptions on which the American College of Medical Genetics (ACMG) Standards and Guidelines for detecting mosaicism in amniotic fluid cultures are based. METHODS: Data from 653 cases of amniotic fluid mosaicism were collected from 26 laboratories. A chi-square goodness-of-fit test was used to compare the observed number of mosaic cases with the expected number based on binomial distribution theory. RESULTS: Comparison of observed data from the in situ colony cases with the expected distribution of cases detected based on the binomial distribution did not reveal a significant difference (P = 0.525). CONCLUSIONS: The empirical data fit the binomial distribution. Therefore, binomial theory can be used as an initial discussion point for determining whether ACMG Standards and Guidelines are adequate for detecting mosaicism.

Prenatal diagnosis of an infant with mosaic trisomy 16 of paternal origin.

We present the first case of an infant with paternally-derived mosaic trisomy 16. Amniocentesis following an elevated maternal serum alpha-fetoprotein level and early fetal growth restriction at 19 weeks detected a high level of mosaicism with 25/33 colonies demonstrating trisomy 16 and 8/33 colonies with a normal 46,XX karyotype. Molecular studies revealed a paternal origin of the trisomy which was present in amniotic fluid cells, representing either a post-zygotic error or a meiosis II non-disjunction without crossing-over. In addition, there was normal biparental inheritance in the normal cell line. The symmetrically growth-restricted fetus was closely monitored for the remainder of the gestation. Decreased fetal movements at 36 weeks in conjunction with electronic fetal monitoring showing evidence of fetal distress necessitated abdominal delivery. Severe growth restriction, mild facial dysmorphism, and cardiac anomalies were identified. Microsatellite analysis demonstrated biparental inheritance in skin fibroblasts with a paternal origin for the trisomy in the placenta. Follow-up cytogenetic studies of additional tissues revealed 85 per cent trisomy 16 mosaicism in the placenta, yet only cytogenetically normal cells in lymphocytes and fibroblasts.

Duplication of the PMP22 gene in 17p partial trisomy patients with Charcot-Marie-Tooth type-1 neuropathy.

Autosomal dominant Charcot-Marie-Tooth type-1A neuropathy (CMT1A) is a demyelinating peripheral nerve disorder that is commonly associated with a submicroscopic tandem DNA duplication of a 1.5-Mb region of 17p11.2p12 that contains the peripheral myelin gene PMP22. Clinical features of CMT1A include progressive distal muscle atrophy and weakness, foot and hand deformities, gait abnormalities, absent reflexes, and the completely penetrant electrophysiologic phenotype of symmetric reductions in motor nerve conduction velocities (NCVs). Molecular and fluorescense in situ hybridization (FISH) analyses were performed to determine the duplication status of the PMP22 gene in four patients with rare cytogenetic duplications of 17p. Neuropathologic features of CMT1A were seen in two of these four patients, in addition to the complex phenotype asociated with 17p partial trisomy. Our findings show that the CMT1A phenotype of reduced NCV is specifically associated with PMP22 gene duplications, thus providing further support for the PMP22 gene dosage mechanism for CMT1A.

Prenatal diagnosis of trisomy 12 mosaicism: physical and developmental follow-up.

Follow-up evaluations were performed on a child at the ages of 2 years 8 months and also at 5 years who had been found on prenatal amniocentesis to be mosaic for trisomy 12. Eight of 36 colonies (22 per cent) were trisomy 12 at amniocentesis, with the remaining colonies showing a normal female karyotype. Cord blood, amnion, chorion, placental, and skin fibroblast chromosome studies failed to show any further evidence of a trisomy 12 cell line. At her evaluations, the child had normal physical and neurological findings. Psychomotor development was appropriate for age on screening.

Familial 10p trisomy resulting from a maternal pericentric inversion.

We report a familial recombination of a pericentric inversion of chromosome 10 resulting in 2 affected relatives who had 10p trisomy and 10q monosomy with the karyotypic abnormality designated rec(10) dup p,inv(10) (p11.2q26). Both of these individuals had the typical characteristics of 10p trisomy, however, at birth the proposita had mild facial anomalies suggesting that the distinct facial characteristics may be of postnatal onset in some cases. In addition, the proposita had gastroesophageal reflux causing severe anemia. The phenotype of our patients is compared to 41 patients with 10p trisomy reported in the literature.

Keratinocytes immortalized by human papillomavirus-18 exhibit alterations dependent upon host genetic background and complexity of viral genes transfected.

Keratinocytes immortalized by the human papillomaviruses (HPVs) vary in cell morphology, growth properties, resistance to inducers of terminal differentiation, and karyotype. To determine the contribution of the host cell genetic background and the HPV genes to these cellular alterations, we have generated and characterized 6 human keratinocyte lines from two different newborn foreskins (A and B) using either the full-length HPV18 genome or the isolated HPV18 E6/E7 genes. The growth properties of the immortalized lines were found to correlate with the complexity of HPV genes present in the transfected vector. Interestingly, cell lines established from foreskin A revealed common chromosomal alterations regardless of the HPV construct utilized for immortalization, and these karyotypic changes differed from those observed in cell lines established from foreskin B, which exhibited their own characteristic aneuploid profile. Thus, chromosomal alterations of HPV-immortalized cells are in part determined by the host genetic background.

Cotransfection of HPV-18 and v-fos DNA induces tumorigenicity of primary human keratinocytes.

Human keratinocytes were cotransfected with the FBJ/R v-fos oncogene and the HPV-18 genome and selected on the basis of their resistance to inducers of terminal differentiation. Unlike keratinocytes immortalized by HPV-18 DNA alone, the HPV-18/v-fos transformants exhibited prominent intracellular vacuolization and formed progressively growing, squamous cell tumors when injected subcutaneously into nude mice. Cytogenetic analysis of two clonally selected transformed cell lines (18/fos clone 1 and 18/fos clone 2) revealed minimal alterations in karyotype, although a consistent rearrangement of chromosome 10, iso(10q), was observed. Further analysis of 18/fos clone 1 confirmed the expression of the fos gene as well as the HPV-18 E7 protein. Alterations in fos gene expression, which appear to be an important facet of epidermal differentiation in vivo, could potentially contribute to the malignant progression of HPV immortalized cells.

Prenatal diagnosis of tetrasomy 12p by in situ hybridization: varying levels of mosaicism in different fetal tissues.

Prenatal diagnosis of tetrasomy 12p is complicated by the discrimination of the 12p isochromosome from the duplication 21q as well as the level of mosaicism demonstrated in the particular tissue sampled. In this disease, a high percentage of chromosomally abnormal cells are generally found in fibroblastic cells, but lymphocyte karyotypes from the same individual may be normal. We report on the pregnancy of a 37-year-old female who presented to our centre at 16 weeks' gestation for genetic amniocentesis. Sonography of the fetus revealed dextrocardia and diaphragmatic hernia. Chromosome analysis of amniocytes demonstrated mosaicism of a 47,XY,+i(12p) line in 80 per cent of cells and a normal male line (20 per cent), consistent with the Pallister-Killian syndrome. Following termination, a 220 g male fetus of 18 weeks was examined. A flattened nose and low-set ears were noted. In situ hybridization with a chromosome 12 centromeric probe in lymphocytes and skin cells unequivocally confirmed the karyotype and showed the presence of a single centromere in the abnormal chromosome, suggesting a true isochromosome. Chromosome analysis of various fetal tissues was performed and the following percentages of abnormal cells were found: skin 100 per cent, chorion 50 per cent, placenta 30 per cent, and blood 80 per cent. The high frequency of tetrasomic cells in fetal blood at this early gestational age is noteworthy, since most reports of this syndrome show a very low percentage of abnormal cells postnatally.