Neuroblastoma and related tumors in Turner's syndrome

Characteristics and karyotype analysis of a patient with turner syndrome complicated with multiple-site tumors: A case report

Turner syndrome (TS) is a congenital chromosomal abnormality that affects approximately 1 in 2,500 people. Both in China and abroad, few studies exist on the incidence of tumors in patients with TS. Most reported cases are complicated with gonadal germ cell tumors, and extragonadal tumors are rare, with the latter not yet being reported in China. Through chromosome karyotype analysis and surgical exploration, a pediatric patent was diagnosed with TS complicated with gonadoblastoma and adrenal neuroblastoma. The patient was short in stature and had a facial deformity. After admission, adrenal computed tomography was conducted, and a right adrenal mass was identified as a neurogenic tumor. After surgical resection and gonadal exploration, the pathological results revealed left gonadoblastoma, right gonadal stromal cell hyperplasia, and ganglion neuroblastoma (mixed type) in the right adrenal gland. Pediatric patients with TS have an increased likelihood of developing neuroblastoma and adrenal-related tumors, and changes in adrenal hormone levels and clinical manifestations are often not obvious when combined with adrenal-related tumors. To avoid missed diagnosis and delayed treatment, screening for adrenal tumors is therefore recommended for patients with TS before the initiation of growth hormone treatment.

Neuroblastic tumors and neurofibromatosis type 1: A retrospective multicenter study in Italy and systematic review of the literature

BACKGROUND

Neuroblastic tumors (NBTs) are the most common extra-cranial solid tumors of childhood. Neurofibromatosis type 1 (NF1) is the most common neurocutaneous disorder with a predisposition to tumors. The co-occurrence of NBTs in the setting of NF1 has been occasionally reported, suggesting a non-casual association and likely configuring a spectrum of neural crest-derived disorders.

AIM OF THE STUDY

To explore the occurrence of NBTs within NF1 and to report on its natural history, therapeutic strategies, and outcomes in an Italian cohort of children with NF1 and in the literature.

SUBJECTS AND METHODS

Study (a): a retrospective analysis of questionnaire-based data [years 1979-2017] derived from the databases of the Italian Registry for Neuroblastoma (RINB) of the Italian Society of Pediatric Onco-Haematology (AIEOP); and Study (b): a systematic review search on NF1/NB co-occurrence.

RESULTS

Study (a) identified eight children with NBTs, 0.2% of patients registered in the RINB, fulfilling the diagnostic criteria for NF1. The primary site of NBTs was abdominal in six patients. The NBTs were neuroblastoma (NB) in five patients, ganglioneuroblastoma (GNB) in one, patient, and ganglioneuroma (GN) in two. Metastatic diffusion occurred in three out of eight children. MYCN gene testing, performed in the tumors of five patients, resulted not-amplified. The major features of NF1 included the following: NF1 family history in four patients, café-au-lait spots in all, freckling in six, Lisch nodules in three, and neurofibromas in three. With regard to the outcome, four children survived three of these for the progression of NB and one for a second tumor. Study (b) identified 12 patients with NF1/NB from the years 1966-2017, and the median age at diagnosis was 27 months (range = 0-168 months). The primary site of NB was thoracic. The prevalent histotype was NB in nine patients, GNB in two, and GN in one. Eight/nine NBs were metastatic. The MYCN gene was amplified in the only studied case. The NF1 features included NF1 family history in seven patients; the major NF1 features were café-au-lait spots in nine patients, freckling in one, Lisch nodules in none, and neurofibromas in six. The outcome was good for only two children, while eight children died of neuroblastoma, at a median age of 49.5 months (range = 2.4-174 months), with a median survival time of 21.75 months after diagnosis.

CONCLUSIONS

To our knowledge, this represents the first systematic study on the occurrence of NBTs in NF1. This confirms that NBs are rare per se in the setting of NF1 (0.2% of all NBs) and even if compared to the overall frequency of malignancies in NF1 (i.e., 14.7%). The male:female ratio in study (a) (0.6) was different from what was recorded in study (b) (1.5) and in line with the overall increased frequency of malignancies in females with NF1. The median ages at diagnosis of NB in either study (a) or (b) were concordant with what occurred in the NB population. In study (a) versus study (b), the frequency of metastatic diffusion was lower, likely indicating less awareness on work-ups for malignancies in old NF1 series in the literature. The outcome was much better in study (a) than in study (b), indicating that multidisciplinary treatment for NB is highly recommended.

Prevention of Growth Failure in Turner Syndrome: Long-Term Results of Early Growth Hormone Treatment in the "Toddler Turner" Cohort

INTRODUCTION

In the randomized "Toddler Turner" study, girls who received growth hormone (GH) starting at ages 9 months to 4 years (early-treated [ET] group) had marked catch-up growth and were 1.6 ± 0.6 SD taller than untreated (early-untreated [EUT]) control girls after 2 years. However, whether the early catch-up growth would result in greater near-adult height (NAH) was unknown. Therefore, this extension study examined the long-term effects of toddler-age GH treatment on height, pubertal development, and safety parameters.

METHODS

Toddler Turner study participants were invited to enroll in a 10-year observational extension study for annual assessments of growth, pubertal status, and safety during long-term GH treatment to NAH for both ET and EUT groups.

RESULTS

The ET group was taller than the EUT group at all time points from preschool to maturity and was significantly taller at the onset of puberty (p = 0.016), however, the difference was not significant at NAH. For the full cohort (ET + EUT combined, n = 50) mean (± SD) NAH was 151.2 ± 7.1 cm at age 15.0 ± 1.3 years. NAH standard deviation score (SDS) was within the normal range (>-2.0) for 76% of ET and 60% of EUT subjects (68% overall) and correlated strongly with height SDS at GH start (r = 0.78; p < 0.01), which in turn had a modest inverse correlation with age at GH start (i.e., height SDS declined with increasing age in untreated girls [r = -0.30; p = 0.016]). No new safety concerns arose.

CONCLUSION

Although the ET group was taller throughout, height SDS at NAH was not significantly different between groups due to catch-down growth of ET girls during lapses in GH treatment after the Toddler study and similar long-term GH exposure overall. Early initiation of GH by age 6 years, followed by uninterrupted treatment during childhood, can prevent ongoing growth failure and enable attainment of height within the normal range during childhood, adolescence, and adulthood.

Congenital malformation syndromes associated with peripheral neuroblastic tumors: A systematic review

Malformation syndromes with predisposition to peripheral neuroblastic tumors (pNT), including neuroblastoma, ganglioneuroblastoma, and ganglioneuroma, may provide clues to critical mutations influencing pNT development. Our objective was to identify and characterize features of pNT associated with specific malformation syndromes. A systematic review of the literature was performed using MEDLINE, Scopus, and Web of Science. We identified 154 of 1014 papers that met eligibility, comprising 207 cases. The patient's age, tumor histology, and frequency of multiple primary tumors varied by malformation syndrome. Genomic studies and systematized reporting are necessary to elucidate cancer risk and the distinct clinical and biological pNT patterns within syndromes.

Recognition and management of adults with Turner syndrome: From the transition of adolescence through the senior years

Turner syndrome is recognized now as a syndrome familiar not only to pediatricians and pediatric specialists, medical geneticists, adult endocrinologists, and cardiologists, but also increasingly to primary care providers, internal medicine specialists, obstetricians, and reproductive medicine specialists. In addition, the care of women with Turner syndrome may involve social services, and various educational and neuropsychologic therapies. This article focuses on the recognition and management of Turner syndrome from adolescents in transition, through adulthood, and into another transition as older women. It can be viewed as an interpretation of recent international guidelines, complementary to those recommendations, and in some instances, an update. An attempt was made to provide an international perspective. Finally, the women and families who live with Turner syndrome and who inspired several sections, are themselves part of the broad readership that may benefit from this review.

Loss of whole chromosome X predicts prognosis of neuroblastoma patients with numerical genomic profile

BACKGROUND

Neuroblastoma (NB), a pediatric tumor of the sympathetic nervous system, is characterized by very frequent chromosomal aberrations at the onset of the disease. Identification of further risk factors for relapse, which could lead to increased survival and potentially reduced late effects among survivors, is still urgently needed. Segmental chromosome aberrations (SCA) are associated with poor prognosis, whereas numerical whole-chromosome aberrations (NCA) are found in patients with a good prognosis; however, a small percentage of the latter patients (10%-15%) subsequently relapse and/or die of disease.

PROCEDURE

DNA copy-number data from 174 NB patients with an NCA genomic profile were analyzed. Association between NCA and event-free survival (EFS) was investigated by the Kaplan-Meier estimator and prognostic decision tree (DT).

RESULTS

DT identified 65 patients with normal chromosome X and an excellent five-year EFS (100%) independently from the stage at diagnosis. The association between poor EFS and whole chromosome X alterations was confirmed after stratification into two groups of different expected prognosis and by internal validation via bootstrap analysis. Furthermore, the association was also observed in an independent cohort of NB patients extracted from the data set of the National Cancer Institute TARGET Project for Neuroblastoma, but sample size was small (n = 75) and statistical significance was not achieved.

CONCLUSIONS

Loss of whole chromosome X may represent a new prognostic marker for NB patients with an NCA genomic profile. If confirmed by further studies, this finding could indicate that such patients should be reclassified as intermediate risk and treated accordingly.

Role of aneuploidy in the carcinogenic process: Part 3 of the report of the 2017 IWGT workgroup on assessing the risk of aneugens for carcinogenesis and hereditary diseases

Aneuploidy is regarded as a hallmark of cancer, however, its role is complex with both pro- and anti-carcinogenic effects evident. In this IWGT review, we consider the role of aneuploidy in cancer biology; cancer risk associated with constitutive aneuploidy; rodent carcinogenesis with known chemical aneugens; and chemotherapy-related malignant neoplasms. Aneuploidy is seen at various stages in carcinogenesis. However, the relationship between induced aneuploidy occurring after exposure and clonal aneuploidy present in tumours is not clear. Recent evidence indicates that the induction of chromosomal instability (CIN), may be more important than aneuploidy per se, in the carcinogenic process. Down Syndrome, trisomy 21, is associated with altered hematopoiesis in utero which, in combination with subsequent mutations, results in an increased risk for acute megakaryoblastic and lymphoblastic leukemias. In contrast, there is reduced cancer risk for most solid tumours in Down Syndrome. Mouse models with high levels of aneuploidy are also associated with increased cancer risk for particular tumours with long latencies, but paradoxically other types of tumour often show decreased incidence. The aneugens reviewed that induce cancer in humans and animals all possess other carcinogenic properties, such as mutagenicity, clastogenicity, cytotoxicity, organ toxicities, hormonal and epigenetic changes which likely account for, or interact with aneuploidy, to cause carcinogenesis. Although the role that aneuploidy plays in carcinogenesis has not been fully established, in many cases, it may not play a primary causative role. Tubulin-disrupting aneugens that do not possess other properties linked to carcinogenesis, were not carcinogenic in rodents. Similarly, in humans, for the tubulin-disrupting aneugens colchicine and albendazole, there is no reported association with increased cancer risk. There is a need for further mechanistic studies on agents that induce aneuploidy, particularly by mechanisms other than tubulin disruption and to determine the role of aneuploidy in pre-neoplastic events and in early and late stage neoplasia.

Genetic susceptibility to neuroblastoma: current knowledge and future directions

Neuroblastoma, a malignancy of the developing peripheral nervous system that affects infants and young children, is a complex genetic disease. Over the past two decades, significant progress has been made toward understanding the genetic determinants that predispose to this often lethal childhood cancer. Approximately 1-2% of neuroblastomas are inherited in an autosomal dominant fashion and a combination of co-morbidity and linkage studies has led to the identification of germline mutations in PHOX2B and ALK as the major genetic contributors to this familial neuroblastoma subset. The genetic basis of "sporadic" neuroblastoma is being studied through a large genome-wide association study (GWAS). These efforts have led to the discovery of many common susceptibility alleles, each with modest effect size, associated with the development and progression of sporadic neuroblastoma. More recently, next-generation sequencing efforts have expanded the list of potential neuroblastoma-predisposing mutations to include rare germline variants with a predicted larger effect size. The evolving characterization of neuroblastoma's genetic basis has led to a deeper understanding of the molecular events driving tumorigenesis, more precise risk stratification and prognostics and novel therapeutic strategies. This review details the contemporary understanding of neuroblastoma's genetic predisposition, including recent advances and discusses ongoing efforts to address gaps in our knowledge regarding this malignancy's complex genetic underpinnings.

Adrenal Ganglioneuroblastoma in Adults: A Case Report and Review of the Literature

Incidentally discovered adrenal masses are very common given the increased number of imaging studies performed in recent years. We here report a clinical case of a 20-year-old woman who presented with left flank pain. Ultrasound examination revealed a contralateral adrenal mass, which was confirmed at computed tomography (CT) scan. Hormonal hypersecretion was excluded. Given the size (11 × 10 × 7 cm) and the uncertain nature of the mass, it was surgically removed and sent for pathological analyses. Conclusive diagnosis was ganglioneuroblastoma. Ganglioneuroblastoma is an uncommon malignant tumor, extremely rare in adults, particularly in females. This neoplasm is frequently localized in adrenal gland.

Neuroblastoma in children: Update on clinicopathologic and genetic prognostic factors

Neuroblastoma is the most common extracranial solid tumor in childhood accounting for 8-10% of all childhood malignancies. The tumor is characterized by a spectrum of histopathologic features and a heterogeneous clinical phenotype. Modern multimodality therapy results in variable clinical response ranging from cure in localized tumors to limited response in aggressive metastatic disease. Accurate clinical staging and risk assessment based on clinical, surgical, biologic and pathologic criteria are of pivotal importance in assigning prognosis and planning effective treatment approaches. Numerous studies have analyzed the presence of several clinicopathologic and biologic factors in association with the patient's prognosis and outcome. Although patient's age, tumor stage, histopathologic classification, and MYCN amplification are the most commonly validated prognostic markers, several new gene mutations have been identified in sporadic and familial neuroblastoma cases that show association with an adverse outcome. Novel molecular studies have also added data on chromosomal segmental aberrations in MYCN nonamplified tumors. In this review, we provide an updated summary of the clinical, serologic and genetic prognostic indicators in neuroblastoma including classic factors that have consistently played a role in risk stratification of patients as well as newly discovered biomarkers that may show a potential significance in patients' management.

Trigeminal Ganglioneuroma: A Rare Case of Trigeminal Neuralgia Caused by Cerebellopontine Angle Tumor

BACKGROUND

Intracranial ganglioneuromas are very rare benign tumors of neural crest origin and generally arise from the peripheral nervous system or adrenal glands. Very few cases of intracranial ganglioneuroma arising from the trigeminal nerve have been reported in the literature, all in East Asia.

CASE DESCRIPTION

A 52-year-old male presented to his primary care physician for evaluation of right facial and periorbital pain for over 18 months. He also reported a two-week history of diplopia with right lateral gaze, which resolved spontaneously. An MRI brain with and without contrast revealed a 3.0 × 2.6 × 2.4 cm enhancing extra-axial mass involving right Meckel's cave with a posterior 1.0 × 1.4 cm lobular component protruding into the prepontine cistern. The patient underwent a right middle fossa craniotomy for a subtemporal surgical resection of the tumor. Histologic section of the tumor demonstrated mature ganglion cells with surrounding satellite cells in a schwannian rich stroma, consistent with mature type ganglioneuroma.

CONCLUSIONS

To the best of our knowledge, this is the sixth case of trigeminal ganglioneuroma; however, it is the first case reported in the United States.

Neonatal tumours

Neonatal or perinatal tumours frequently relate to prenatal or developmental events and have a short exposure window which provides an opportunity to study tumours in a selective sensitive period of development. As a result, they display a number of host-specific features which include occasional spontaneous maturational changes with cells still responding to developmental influences. Neonatal tumours (NNT) are studied for a number of important reasons. Firstly, many of the benign tumours arising from soft tissue appear to result from disturbances in growth and development and some are associated with other congenital anomalies. Study of these aspects may open the door for investigation of genetic and epigenetic changes in genes controlling foetal development as well as environmental and drug effects during pregnancy. Secondly, the clinical behaviour of NNT differs from that of similar tumours occurring later in childhood. In addition, certain apparently malignant NNT can 'change course' in infancy leading to the maturation of apparently highly malignant tumours. Thirdly, NNT underline the genetic associations of most tumours but appear to differ in the effects of proto-oncogenes and other oncogenic factors. In this context, there are also connections between the foetal and neonatal period and some "adult" cancers. Fourthly, they appear to arise in a period in which minimal environmental interference has occurred, thus providing a unique potential window of opportunity to study the pathogenesis of tumour behaviour. This study will seek to review what is currently known in each of these areas of study as they apply to NNT. Further study of the provocative differences in tumour behaviour in neonates provides insights into the natural history of cancer in humans and promotes novel cancer therapies.

Ganglioneuroma of adrenal gland in a patient with Turner syndrome

A 15-year-old girl with Turner syndrome was unexpectedly found to have a left suprarenal mass. Extensive investigations showed a clinically and biochemically inapparent mass. Computed tomography disclosed a well-defined solid lesion in the left adrenal measuring 6.5 x 5 cm with minimal contrast enhancement. Laparoscopic adrenalectomy was done. Histologic examination revealed an encapsulated mass originated from the left adrenal medulla. Tumor tissue comprised abundant collagen fibers and spindloid cells admixed with mature ganglion cells. The tumor was diagnosed as left adrenal ganglioneuroma. According to literature, we report the eighth case of ganglioneuroma complicating Turner syndrome. Patients with this syndrome are predisposed to the development of neuroblastoma and related tumors. Reasons for this predisposition might relate to genetic and hormonal factors. Given that these tumors are often limited stage and of good prognosis, we recommend their screening in all patients with Turner syndrome.

Neuroblastoma in a patient with Coffin-Siris syndrome

We report the case of an 8-year-old boy with the phenotypic features of Coffin-Siris syndrome diffuse hypertrichosis, flat occiput, scant scalp hair, flat supraorbital arch, triangular eyebrows, horizontal palpebral fissure, anteverted nares, triangular philtrum, coarse lips, high-arched palate, micrognathia, low set and dorsaly rotated ears, short neck, wide thorax, widely set nipples, transverse palmar crease, psychomotor delay, urinary malformations (paraurethral diverticulum, hypoplasia of left kidney associated with vesicoureteral reflux grade 3-4), bilateral inguinal hernia, and dorsolumbar kyphoscoliosis. In the follow-up he presented a retroperitoneal neuroblastoma. Although this type of tumor has been referred to develop in several genetic and mutimalformative syndromes, it seems that present association has not been previously reported.

Successful resection of a re-occurred pulmonary myosarcoma in a patient with turner syndrome mosaic

We describe a patient who underwent thoracic radiation therapy for biopsy-proven pulmonary spindle cell sarcoma in the left lower lobe, 15 months after birth. At the age of 37 she developed shoulder pain, fatigue, and progressive exertion dyspnoea. Chest X-ray revealed a pulmonary mass in the left lower lobe due to a cytology-proven malignant tumour.The patient underwent left pneumonectomy. Histology revealed a myosarcoma of the lung, similar to the previous sarcoma. Furthermore, the patient was diagnosed to have Turner syndrome mosaic and chromosomal analysis revealed a translocation t(1;13) in 3/50 metaphases. However a germline mutation of the p53 tumour suppressor gene was excluded. After 2 years of follow-up the patient is stable and there are no signs of recurrence of the tumour.We conclude a re-occurrence of this very rare malignant disorder of the lung after a 36-year interval in a patient with Turner syndrome mosaic. Following initial curative radiation therapy, with a remission over 36 years, lung resection was now successfully performed.

Sporadic aneuploidy in PHA-stimulated lymphocytes of Turner's syndrome patients

In line with the view that aneuploidy destabilizes the karyotype, initiating an autocatalytic process that gives rise to further loss and/or gain of chromosomes, we examined whether a constitutional aneuploidy such as monosomy for one chromosome is associated with sporadic loss and/or gain of other chromosomes. We used PHA-stimulated lymphocytes from eight women with Turner's syndrome (six displayed X chromosome monosomy ranging from 60.2% to 97.9%, and two were below 10%), and eight healthy women who served as a control group. Fluorescence in-situ hybridization (FISH), applied at interphase, was used to evaluate the level of aneuploidy for three randomly selected chromosomes (autosomes 8, 15 and 18) in each sample. For each tested chromosome, our results showed a significantly higher level of aneuploid cells in the samples from patients than in those from controls (p < 0.01). The mean level of aneuploid cells for all three tested autosomes was almost twice as high in the patient samples as in the control samples (p < 0.002). It is noteworthy that, in the Turner's syndrome patients, X chromosome disomic cells also displayed increased levels of aneuploidy. It is possible that monosomy of X chromosome in female cells destabilizes their own genome and also affects X disomic cells in the region. One may also speculate that a common factor(s) is involved with both constitutional and sporadic aneuploidy.

Ganglioneuroma Manifesting as an Incidental Adrenal Mass in an Adult With Turner’s Syndrome

OBJECTIVE

To report a case of ganglioneuroma masquerading as an incidental adrenal mass in an adult patient with Turner's syndrome.

METHODS

We present the clinical, laboratory, radiologic, and pathologic findings in this patient.

RESULTS

A 31-year-old woman with Turner's syndrome who had previously been treated with growth hormone replacement had an incidentally discovered mass, apparently arising from the left adrenal gland. The mass was "silent" clinically and biochemically, but imaging characteristics were not reassuring for a benign cortical adenoma. Because of uncertainty regarding the nature of the mass, it was removed laparoscopically; during this procedure, it was noted to be intimately associated with, but anatomically distinct from, the left adrenal gland. The pathology report confirmed the presence of a benign ganglioneuroma.

CONCLUSION

Although ganglioneuroma has previously been noted to be associated with Turner's syndrome (especially in pediatric patients), to the best of our knowledge this is the first report of a ganglioneuroma manifesting as an incidental adrenal mass in an adult patient with Turner's syndrome.

Epidemiology and genetics of childhood cancer

Childhood cancer is rare everywhere in the world, with age-standardized annual incidence usually between 70 and 160 per million at age 0-14 years. Greater variation is seen between populations for some specific tumour types. Some of the largest variations are geographical and are attributable to environmental factors, whereas variation mainly on ethnic lines seems likely to be a marker of genetic predisposition. A wide range of familial and genetic syndromes is associated with an increased risk of childhood cancer. Virtually all the excess risk of cancer among first-degree relatives of children with cancer can be accounted for by known hereditary syndromes. Studies of weak predisposition and gene-environment interaction have so far shown limited consistency. There are very few established environmental or exogenous risk factors and most of these are infective agents. Many putative risk factors can hardly ever be investigated epidemiologically except by interview or questionnaire studies. Some recent examples illustrate the continuing problems of participation bias and recall bias.

Abnormal constitutional karyotypes in patients with neuroblastoma: a report of four new cases and review of 47 others in the literature

Anomalies of constitutional karyotype, which have led to the discovery of oncogenes and tumor-suppressor genes in embryonal tumors such as retinoblastoma and Wilms tumor, have, until recently, rarely been reported until recently in neuroblastoma. We present four new cases of neuroblastoma associated with (a) a mosaicism for monosomy 22; (b) an 11q interstitial deletion; (c) a pericentric inversion of chromosome 9 at band 9p21; and (d) a Robertsonian translocation t(13;14). These anomalies and 47 others in the literature are worthy of interest, because some are recurrent, involving the same chromosome regions (1p36, 2p23, 3q, 11q23, and 15q), and some anomalies are situated on chromosome regions known to contain genes involved in neuroblastoma development (1p, 2p, 9p, 11q, 16q, and 17q). Chromosome regions 3q and 15q, observed several times, may also contain genes significant for neuroblastoma onset or development. Furthermore, the lack of neuroblastoma in patients with Down syndrome and Klinefelter or triple-X syndromes, together with a probable excess of neuroblastoma in patients with Turner syndrome, suggests that genes of importance for neuroblastoma may map to chromosomes X and 21. A search for genes implicated in neuroblastoma biology should use these data.

Asynchronous replication of biallelically expressed loci: a new phenomenon in Turner syndrome

PURPOSE

Transcriptional activity of genes is related to their replication timing; alleles showing the common biallelic mode of expression replicate synchronously, whereas those with a monoallelic mode of expression replicate asynchronously. Here the level of synchronization in replication timing of alleles was determined in subjects with Turner syndrome.

METHODS

Fluorescence in situ hybridization was used for three loci not linked to X chromosome, in lymphocytes derived from 12 controls, 3 individuals with Turner, and 4 with mosaic Turner syndrome.

RESULTS

In cells derived from controls, each pair of alleles replicated synchronously; yet these same alleles replicated asynchronously in cells monosomic for X chromosome derived from Turner and mosaic Turner patients. When the level of 45,X was low in the mosaic samples, the replication pattern of the 46,XX cells was normal. However, in samples with a high level of mosaicism, a significantly increased asynchronous replication was detected in the 46,XX cells.

CONCLUSION

An altered temporal replication control in Turner syndrome affecting the aneuploid and euploid cells is shown. This alteration may potentially be involved in the determination of the syndrome.

Evaluation of constitutional chromosome aberrations in hematologic disorders

We have reviewed 4164 patients with various hematologic disorders cytogenetically studied in our laboratory during the last 25 years to analyze the frequency of constitutional chromosome aberrations (CCA) and to evaluate their association with hematologic malignancies. Our population of patients included 1133 pediatric patients and 3031 adults. Twenty-four (0.58%) cases showed CCA. They included four patients with Robertsonian translocations, one patient with a balanced translocation, two patients with sex chromosome abnormalities, and 17 cases with Down syndrome (DS). Nonsignificant differences among the frequency of patients with CCA from our hematologic series and those observed in the two largest combined surveys of livebirth published (0.65-0.84%) were found. The incidence of DS patients in our population (0.41%) was approximately three times higher than of that observed at birth (0.12-0.17%; P<0.001). The total incidence of constitutional chromosome abnormalities in the non-DS hematologic patients was 0.168% (7 of 4164) lower than of that observed in the newborn population (0.51-0.67%; P<0.001). Nonsignificant differences were found when the incidences of structural aberrations and sex chromosome anomalies were individually compared with the data of the overall population. Our results suggest that the presence of a CCA, other than DS, would not predispose patients to hematologic malignancies.