Variations of sex development: The first German interdisciplinary consensus paper

INTRODUCTION

The term variations of sex development subsumes a large number of congenital conditions including chromosomal mosaics and variations of chromosomal, gonadal, and phenotypic sex. A situation of this nature may cause severe distress to both, parents and affected persons. One of the reasons for this is the binary form of gender classification in the society. In the past, because of a fear of possible stigmatization and an inability to cope with complex situations, it has been medical policy and practice for newborns to undergo early, mostly 'feminizing' elective surgery with the aim of achieving an outer genital appearance that is unambiguously male or female. Protests by advocacy groups for the most part as well as the results of outcome studies have shown that the development of affected persons may be very different to what has been expected and often does not result in the intended clear female or male gender identity as had been intended. It, therefore, seemed a matter of urgency to implement this new awareness as well as the ethical and personal human rights perspectives in the recommendations for the medical and psychosocial management of diverse sex development (DSD) in the future.

STUDY DESIGN

In 2012, an interdisciplinary group of German academics engaged in the field of DSD decided to work on a consensus paper for this topic. It involved the participation of all faculties and non-scientific groups dealing with DSD, in particular advocacy and service-user groups. In a structured consensus, process recommendations were developed based on scientific literature as well as personal experiences of clinicians and affected individuals.

RESULTS

Finally, 37 recommendations were agreed on. The strength of consensus is reflected in the degree of agreement as expressed in percentages.

CONCLUSION

The introduction of the consensus paper reflects on the emerging paradigm shift and the necessity for a more open view of gender within society. The paper is intended to aid the performance of appropriate diagnostics in DSD-affected newborns and especially to help parents and affected persons cope with the biological and social consequences of DSD. With regard to medical or surgical therapy, it gives information about the most recent treatment trends.

Mutations in WNT9B are associated with Mayer-Rokitansky-Küster-Hauser syndrome

Mayer-Rokitansky-Küster-Hauser syndrome (MRKHS) is a well-known malformation pattern of the Müllerian ducts (MDs) characterized by congenital absence of the uterus and vagina. To date, most cases remain unexplained at molecular level. As female Wnt9b-/- mice show a MRKHS-like phenotype, WNT9B has emerged as a promising candidate gene for this disease. We performed retrospective sequence analyses of WNT9B in 226 female patients with disorders of the MDs, including 109 patients with MRKHS, as well as in 135 controls. One nonsense mutation and five likely pathogenic missense mutations were detected in WNT9B. Five of these mutations were found in cases with MRKHS accounting for 4.6% of the patients with this phenotype. No pathogenic mutations were detected in the control group (p = 0.017). Interestingly, all of the MRKHS patients with a WNT9B mutation were classified as MRKHS type 1, representing 8.5% of the cases from this subgroup. In previous studies, two of the patients with a WNT9B mutation were found to carry either an additional deletion of LHX1 or a missense mutation in TBX6. We conclude that mutations in WNT9B were frequently associated with MRKHS in our cohort and some cases may be explained by a digenic disease model.

X-exome sequencing of 405 unresolved families identifies seven novel intellectual disability genes

X-linked intellectual disability (XLID) is a clinically and genetically heterogeneous disorder. During the past two decades in excess of 100 X-chromosome ID genes have been identified. Yet, a large number of families mapping to the X-chromosome remained unresolved suggesting that more XLID genes or loci are yet to be identified. Here, we have investigated 405 unresolved families with XLID. We employed massively parallel sequencing of all X-chromosome exons in the index males. The majority of these males were previously tested negative for copy number variations and for mutations in a subset of known XLID genes by Sanger sequencing. In total, 745 X-chromosomal genes were screened. After stringent filtering, a total of 1297 non-recurrent exonic variants remained for prioritization. Co-segregation analysis of potential clinically relevant changes revealed that 80 families (20%) carried pathogenic variants in established XLID genes. In 19 families, we detected likely causative protein truncating and missense variants in 7 novel and validated XLID genes (CLCN4, CNKSR2, FRMPD4, KLHL15, LAS1L, RLIM and USP27X) and potentially deleterious variants in 2 novel candidate XLID genes (CDK16 and TAF1). We show that the CLCN4 and CNKSR2 variants impair protein functions as indicated by electrophysiological studies and altered differentiation of cultured primary neurons from Clcn4(-/-) mice or after mRNA knock-down. The newly identified and candidate XLID proteins belong to pathways and networks with established roles in cognitive function and intellectual disability in particular. We suggest that systematic sequencing of all X-chromosomal genes in a cohort of patients with genetic evidence for X-chromosome locus involvement may resolve up to 58% of Fragile X-negative cases.

Experts' Opinion on the Prenatal Therapy of Congenital Adrenal Hyperplasia (CAH) Due to 21-Hydroxylase Deficiency - Guideline of DGKED in cooperation with DGGG (S1-Level, AWMF Registry No. 174/013, July 2015)

Purpose: This guideline of the German Society of Pediatric Endocrinology and Diabetology (DGKED) is designed to be experts' opinion on the current concept of prenatal therapy for congenital adrenal hyperplasia due to 21-hydroxylase deficiency (CAH). Several scientific medical societies have also participated in the guideline. It aims to offer guidance to physicians when they counsel affected families about prenatal therapy. Methods: The experts commissioned by the medical societies developed a consensus in an informal process. The consensus was subsequently confirmed by the steering committees of the respective medical societies. Recommendations: Prenatal CAH therapy is an experimental therapy. We recommend designing and using standardized protocols for the prenatal diagnosis, therapy and long-term follow-up of women and children treated prenatally with dexamethasone. If long-term follow-up is not possible, then prenatal therapy should not be performed.

CD34(+) lineage specific donor cell chimerism for the diagnosis and treatment of impending relapse of AML or myelodysplastic syndrome after allo-SCT

After allo-SCT, analysis of CD34(+) lineage-specific donor cell chimerism (DCC) is a sensitive method for monitoring minimal residual disease in patients with AML or myelodysplastic syndrome (MDS) with CD34 expression. To substantiate evidence of whether immune interventions in patients with impending relapse, defined by incomplete lineage-specific DCC, may prevent hematological relapse, we performed a retrospective nested case control study. Unsorted and lineage-specific DCC were measured in 134 patients. Forty-three patients had an incomplete CD34(+)-DCC with no other evidence of relapse. After immediate tapering of immunosuppressive treatment (30 patients) and/or infusion of donor lymphocytes (10 patients), 21 patients remained in remission (conversion to complete lineage-specific DCC) and 22 relapsed. Relapse-free survival at 3 years of the 91 patients with stable DCC and of the 43 patients with incomplete DCC was 74% (95% confidence interval (CI), 64-83%) and 40% (95% CI, 24-58%), respectively. OS rates were 79% (95% CI, 70-88%) and 52% (95% CI, 35-69%), respectively. These results, with 49% of patients with impending relapse successfully treated with immune intervention, highly suggest that analysis of CD34(+)-DCC is an important tool for monitoring and the management of AML and MDS patients after allo-SCT.

Analysis of the Wilms' tumor suppressor gene (WT1) in patients 46,XY disorders of sex development

CONTEXT

The Wilms' tumor suppressor gene (WT1) is one of the major regulators of early gonadal and kidney development. WT1 mutations have been identified in 46,XY disorders of sex development (DSD) with associated kidney disease and in few isolated forms of 46,XY DSD.

OBJECTIVE

The objective of the study was the evaluation of WT1 mutations in different phenotypes of isolated 46,XY DSD and clinical consequences.

DESIGN

The design of the study was: 1) sequencing of the WT1 gene in 210 patients with 46,XY DSD from the German DSD network, consisting of 150 males with severe hypospadias (70 without cryptorchidism, 80 with at least one cryptorchid testis), 10 males with vanishing testes syndrome, and 50 raised females with partial to complete 46,XY gonadal dysgenesis; and 2) genotype-phenotype correlation of our and all published patients with 46,XY DSD and WT1 mutations.

RESULTS

We have detected WT1 mutations in six of 80 patients with severe hypospadias (7.5%) and at least one cryptorchid testis and in one of 10 patients with vanishing testes syndrome (10%). All patients except one developed Wilms' tumor and/or nephropathy in childhood or adolescence.

CONCLUSION

WT1 analysis should be performed in newborns with complex hypospadias with at least one cryptorchid testis and in isolated 46,XY partial to complete gonadal dysgenesis. Kidney disease might not develop until later life in these cases. WT1 analysis is mandatory in all 46,XY DSD with associated kidney disease. WT1 analysis is not indicated in newborns with isolated hypospadias without cryptorchidism. Patients with WT1 mutations should be followed up closely because the risk of developing a Wilms' tumor, nephropathy, and/or gonadal tumor is very high.

Bcar3 is expressed in sertoli cells and germ cells of the developing testis in mice

We identified Bcar3 in the course of a screen for developmentally regulated genes at early developmental stages in mouse embryos. In this study, we explored the spatio-temporal expression pattern of Bcar3 during the critical time period of sex determination using in situ hybridization, real-time RT-PCR, and immunohistochemistry. We found that Bcar3 is expressed in XY gonads during early stages of gonad development and that BCAR3 localizes to Sertoli cells and germs cells. In addition, we identified a new alternative Bcar3 transcript in which exons 4-7 are deleted. This deletion could result in the generation of a truncated BCAR3 protein lacking functional domains including the SH2 domain. The data presented here suggest that Bcar3 could play a role in gonad development.

Genetische Ursachen der prämaturen Ovarialinsuffizienz und Ovardysgenesie

Die prämature Ovarialinsuffizienz (POI) ist durch eine Amenorrhö vor dem 40. Lebensjahr und einen hypergonadotropen Hypogonadismus gekennzeichnet. Die Prävalenz für Frauen mit 40 Jahren liegt bei 1%. Die Ovardysgenesie, welche durch einen kompletten Follikelverlust vor der Geburt charakterisiert ist, kann als die schwerste Manifestation einer POI angesehen werden. Die POI tritt in der Mehrzahl isoliert auf, kann aber auch Teil einer syndromalen Erkrankung sein. Neben exogenen Faktoren kommen auch genetische Faktoren wie Chromosomenaberrationen, monogenetische Defekte und eine polygen-multifaktorielle Genese in Frage. Inzwischen sind mehr als 30 Gene bekannt, deren Mutationen zur POI führen. Dennoch ist in der Mehrzahl der Fälle die Ätiologie der POI weiterhin unbekannt.

Mutations of the SRY-responsive enhancer of SOX9 are uncommon in XY gonadal dysgenesis

During mouse sex determination, SRY upregulates the core testis-specific enhancer of Sox9, TESCO. Mutations in human SRY are found in one third of cases with XY pure gonadal dysgenesis (XY GD; Swyer syndrome), while two thirds remain unexplained. Heterozygous SOX9 mutations can cause XY GD in association with the skeletal malformation syndrome campomelic dysplasia. We hypothesized that human TESCO mutations could cause isolated XY GD. Sixty-six XY GD cases with an intact SRY were analyzed for TESCO point mutations or deletions. No mutations were identified. We conclude that TESCO mutations are not a common cause of XY GD.

Array-CGH analysis in patients with syndromic and non-syndromic XY gonadal dysgenesis: evaluation of array CGH as diagnostic tool and search for new candidate loci

BACKGROUND

XY gonadal dysgenesis (XY-GD) is a heterogeneous disorder characterized by failure of testicular development despite a normal male karyotype. Non-syndromic and syndromic forms can be delineated. Currently, only a minority of cases can be explained by gene mutations.

METHODS

The aim of this study was to detect microdeletions and duplications by using high-resolution Agilent oligonucleotide arrays in a cohort of 87 patients with syndromic or non-syndromic 46,XY-GD.

RESULTS

In 26 patients, we identified gains or losses in regions including genes involved in XY-GD (DMRT1, SOX9, DAX1) or in regions, which have not been described as polymorphic copy number variants (CNVs).

CONCLUSIONS

This study shows that array comparative genomic hybridization (CGH) analysis is a useful tool for the molecular diagnosis of XY-GD as well as for the identification of potential candidate genes involved in male sexual development.

Copy number variants in premature ovarian failure and ovarian dysgenesis

Premature ovarian failure (POF) is a heterogeneous group of disorders with amenorrhea and high serum gonadotropins in women of less than 40 years. Ovarian dysgenesis (OD) which is characterised by the loss of follicles before puberty describes the most severe POF outcome. Although a multitude of different factors including non-genetic as well as genetic causes are known to play a role in the development of POF and OD, the underlying etiology remains unsolved in the majority of cases. In the last years, array-CGH was found to be a very useful tool in the identification of candidate genes in different conditions. Therefore, we performed array-CGH analysis by using high-resolution Agilent oligonucleotide arrays in a total of 74 POF and OD patients and identified 44 private losses and gains potentially causative for POF. It is striking to note that a lot of the genes involved in these rearrangements can be classified in (i) genes involved in meiosis (e.g. PLCB1, RB1CC1, MAP4K4), (ii) genes involved in DNA repair (e.g. RBBP8) and (iii) genes involved in folliculogenesis or male fertility in homologs of model organisms (e.g. IMMP2L, FER1L6, MEIG1).

New technologies for the identification of novel genetic markers of disorders of sex development (DSD)

Although the genetic basis of human sexual determination and differentiation has advanced considerably in recent years, the fact remains that in most subjects with disorders of sex development (DSD) the underlying genetic cause is unknown. Where pathogenic mutations have been identified, the phenotype can be highly variable, even within families, suggesting that other genetic variants are influencing the expression of the phenotype. This situation is likely to change, as more powerful and affordable tools become widely available for detailed genetic analyses. Here, we describe recent advances in comparative genomic hybridisation, sequencing by hybridisation and next generation sequencing, and we describe how these technologies will have an impact on our understanding of the genetic causes of DSD.

Blood chimerism in a girl with Down syndrome and possible freemartin effect leading to aplasia of the Müllerian derivatives

Cytogenetic and molecular genetic analysis in a case of sex-discordant dizygotic twins revealed blood chimerism in the girl (46,XY in blood and 47,XX, + 21 in fibroblasts) caused by feto-fetal transfusion from her healthy brother. The girl presented with Down syndrome, aplasia of the uterus and the Fallopian tubes and normal female external genitalia. We propose that the lack of Müllerian structures is caused by the effect of the Müllerian inhibiting substance transferred from the male to the female twin in early pregnancy. This disorder of sex development is known as freemartin phenomenon in female cattle from sex-discordant twin pairs.

Prevalence Rates of Pathogenic Mutations in the BRCA1 and BRCA2 Genes in Families with Different Disease Histories: Results from the German Consortium for Hereditary Breast and Ovarian Cancer

Introduction: In the German Consortium for Hereditary Breast and Ovarian Cancer (GC-HBOC), a large number of families with different histories of breast and ovarian cancers was screened for pathogenic mutations in the tumor-suppressor genes BRCA1/2. We here aimed to analyse the prevalence rates of pathogenic mutations for various familial disease histories.Methods: From 1997-2009 more than 6,000 families were screened for pathogenic mutations in BRCA1/2. Mutation analysis was performed by DHPLC (denaturing high-performance liquid chromatography) pre-screening, direct sequencing of suspect fragments and MLPA (multiplex ligation-dependant probe amplification) in at least one index case of these families. Complete pedigree information over three generations was used for the analysis. All lineages within a pedigree were traced and checked for the presence of several predefined disease histories.Results: Detailed mutation prevalence rates have been determined for a variety of familial risk situations. The highest mutation prevalence rate (78%, 95%CI 67-87%) was seen in families with at least two relatives affected by pre-menopausal breast cancer and at least two affected by ovarian cancer at any age. Importantly, the presence of a single woman affected by breast and ovarian cancer or bilateral breast cancer with first breast cancer under the age of 41 was associated with a BRCA1/2 mutation prevalence of 53% (95%CI 48-59%) and 34% (95%CI 23-47%) respectively. Interestingly, low mutation prevalence rates of <10% were found in families with only one case of male breast cancer (9%, 95%CI 4-19%), and in families with three or more cases of postmenopausal breast cancer (7%, 95%CI 4-14%), the former being only BRCA2 mutations. Overall, the mutation prevalence was 27% (95% CI 26-29%) in the whole cohort.Conclusion: We provide comprehensive estimates for BRCA1/2 mutation prevalence rates that are based on a large number of families with comprehensive pedigree information. Such estimates can be used to develop cost effective screening strategies for public health care providers.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4073.

WNT4 and RSPO1 are not involved in a case of male-to-female sex reversal with partial duplication of 1p

Some studies suggest that WNT4 signaling acts to repress the male pathway and a single case of duplication of WNT4 located in 1p35 has been associated with ambiguous genitalia. Recently, RSPO1 located in 1p34.3 was shown to be essential in sex determination. We show that neither WNT4 nor RSPO1 are duplicated in another case of male-to-female sex reversal with partial duplication of 1p. Therefore, it can be assumed that in male-to-female sex reversal associated with duplication of 1p, other genetic factors may be involved.

Familial translocation t(1;9) associated with macromastia: molecular cloning of the breakpoints

A familial reciprocal translocation associated with severe macromastia has been characterized by molecular cytogenetic and molecular analysis. Cloning of the translocation breakpoints revealed that no known gene has been disrupted by this translocation. Therefore, a position effect compromising the regulation of a still to be identified gene in the vicinity of the breakpoints can be assumed.

Male infertility as a component of Carney complex

Carney complex (CNC) is a multiple neoplasia syndrome characterised by endocrine tumours, spotty skin pigmentation, cardiac and other myxomas, psamommatous and pigmented schwannomas, large cell calcifying Sertoli cell tumours, and mammary ductal adenomas and other more rare lesions. CNC is inherited in an autosomal-dominant manner and has been mapped to at least two chromosomal loci. Patients who map to the CNC1 locus located on chromosome 17 carry inactivating mutations of the PRKAR1A gene that encodes the cAMP-dependent protein kinase regulatory subunit type 1-alpha (Kirschner et al., 2000). One gene responsible for type 2 (CNC2) is located on chromosome 2p16. Infertility in CNC can be caused by a number of factors; there is evidence that prkar1a deficiency in mice leads directly to infertility (Burton et al., 2006), but patients with CNC also have Sertoli cell tumours and a number of other reasons to affect fertility. We report on an infertile male with CNC and present evidence that male infertility should be considered as part of the phenotype of CNC.

Contiguous gene deletions involving EFNB1, OPHN1, PJA1 and EDA in patients with craniofrontonasal syndrome

Craniofrontonasal syndrome (CFNS [MIM 304110]) is an X-linked malformation syndrome characterized by craniofrontonasal dysplasia and extracranial manifestations in heterozygous females. In the majority of patients CFNS is caused by mutations in the EFNB1 gene (MIM 300035). We identified three girls with classical CFNS and mild developmental delay harboring de novo deletions of the EFNB1 gene. Applying haplotype analysis, Southern blot hybridization and array-comparative genomic hybridization, deletion of EFNB1 was found to be part of contiguous gene deletions in the patients. In one patient the deletion interval includes the genes for oligophrenin-1 (OPHN1 [MIM 300127]) and praja 1 (PJA1 [MIM 300420]). In the second patient the deletion includes OPHN1, PJA1 and the gene for ectodysplasin A (EDA [MIM 300451]). In the third patient EFNB1 gene deletion may include deletion of regulatory regions 5' of OPHN1. Previously, the OPHN1 gene has been shown to be responsible for recessive X-linked mental retardation. Although it is too early to predict the future cognitive performance of the two infant patients with contiguous gene deletions of OPHN1-EFNB1-PJA1, mild learning disabilities have been recognized in the older, third patient. It is important for genetic counseling to be aware that their male offspring may not only be carriers of CFNS but may also be affected by mental retardation and anhidrotic ectodermal dysplasia.

Deleted In Cancer 1 (DICE1): Search for a function in prostate carcinoma (PCa)

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Background: Recently, DICE1 gene (MIM 604331 ) was identified to colocalize with the microsatellite marker D13S284 in 13q14.3, a region frequently affected by allelic deletion in PCa. We previously showed that DICE1 mRNA expression is down-regulated in PCa cell lines compared to normal prostate tissue, due to DICE1 promoter hypermethylation; suggesting that DICE1 is a tumor suppressor gene. Methods: Human PCa cell lines PC3 and DU145 were lipo-transfected with mammalian expression plasmids encoding for the full length DICE1 gene or for its N- (APAI construct) and C-terminal (DEAD construct) fragments. The constructs expression was determined by semi-quantitative PCR and quantified by Real-time PCR. Clonogenic formation and apoptotic assays were performed. Results: The PCR analysis showed that the expression of DICE1, APAI and DEAD domains in transfected PC3 and DU145 cell lines was increased 30.6, 75.2 and 27.9 fold in PC3 cells and 4.3, 5 and 2.5 fold in DU145 cells, respectively, compared to non-transfected cells. The function analysis showed that the ectopic expression of DICE1 suppressed clonogenic growth of PC3 and DU145 cell lines. Surprisingly, we showed that like DICE1, DEAD and APAI inhibit the PC3 and DU145 clonogenic growth suggesting that both regions are involved in prostate tumor growth inhibition. The apoptosis assay could not show any DNA fragmentation activity for DICE1. Conclusions: We demonstrated that DICE1 is a tumor suppressor in PCa. DICE1 mRNA expression is down-regulated in PCa cell lines compared to normal prostate tissue and its ectopic expression in PCa cell lines inhibits their capacity to form clonogenic colonies in vitro. The functional analysis could not reveal any role of DICE1 in PCa apoptosis, suggesting that other molecular mechanisms are involved.

No significant financial relationships to disclose.

Congenital cataract, ataxia, external ophthalmoplegia and dysphagia in two siblings. A Marinesco-Sjögren-like syndrome

Marinesco-Sjögren syndrome (MSS) is an autosomal recessive multiorgan disorder with clinical and genetic heterogeneity. The key features of MSS include cerebellar ataxia, early bilateral cataracts, delayed motor development, and to a varying degree mental retardation. The syndrome was recently mapped to chromosome 5q31, and loss-of-function mutations in the SIL1 gene have been identified as the primary pathology. Here, we describe two German siblings with clinical characteristics resembling those seen in many cases of MSS except that a marked cerebellar atrophy was not detectable in our patients. In addition, both patients presented with external ophthalmoplegia and paralytic dysphagia. Sequencing of all 10 exons of the SIL1 gene did not detect any SIL1 mutation in our patients.

Genotype/phenotype correlation in a patient with partial monosomy 15 and partial trisomy 14

We report on a girl with severe mental and psychomotor retardation caused by an unusual, unbalanced translocation t(14;15) of maternal origin. The unbalanced translocation in the patient resulted in trisomy 14pter-->q13 and monosomy 15pter-->q11.2. In addition to common features described in other patients with small proximal trisomies of chromosome 14, our patient presented with hypopigmented skin with light hair and eye color and severe speech impairment. Therefore the phenotype of the girl shows few similarities to that of Angelman syndrome patients, although the breakpoint in chromosome 15 in our patient was found to be proximal to the PWS/AS region.

Ectopic expression of DICE1 suppresses tumor cell growth

The tumor suppressor gene DICE1 is located within a previously reported critical region of loss of heterozygosity on chromosome 13q14.3. Expression of the remaining DICE1 allele is down-regulated in non-small cell lung carcinomas. Ectopic expression of DICE1 cDNA by DICE1-green fluorescent protein fusion constructs resulted in inhibition of colony formation of human non-small cell lung carcinoma cell line SK-MES-1 and NCI-H520 and prostate carcinoma cell line DU145. In IGF-IR transformed Balb/c 3T3, DICE1 substantially sup-pressed growth in soft agar. These results demonstrate that DICE1 has a growth-suppressing activity and interferes with anchorage-independent growth of IGF-IR transformed tumor cells dependent upon IGF-I signaling.

Multi-locus (ML)-FISH is a reliable tool for nondisjunction studies in human oocytes

In the present study, we developed a fluorescence in situ hybridization (FISH) strategy, which allows a reliable determination of the chromatid number of specific chromosomes in mature human oocytes. 168 unfertilized oocytes were analyzed by dual-color FISH with two direct-labeled locus-specific DNA probes for chromosome 13 and 21. To exclude FISH failures, metaphases with abnormal signal patterns were reanalyzed by multi-locus-FISH (ML-FISH) for chromosome 13 and 21. Following dual-color FISH, abnormal signal patterns were detected in 21 out of 108 metaphases (19.4%). 17 of these metaphases were reanalyzed by ML-FISH. In contrast to the first FISH, seven metaphases showed normal signal patterns after rehybridization, whereas ten metaphases remained abnormal. Out of these real aneuploid metaphases, five showed gain or loss of a single signal (= chromatid), two showed missing double signals (= chromosome) and three showed both. In conclusion, locus-specific FISH probes facilitate differentiation between first meiotic nondisjunction of whole chromosomes and prematurely divided chromatids. Moreover, simultaneous hybridization with a second locus-specific probe on the same chromatid (ML-FISH) helps to differentiate between FISH failures and real meiotic division errors and therefore, allows a more reliable analysis of aneuploidies in human oocytes.

Mapping of a further locus for X-linked craniofrontonasal syndrome

Craniofrontonasal syndrome is a rare dysostosis syndrome with an unusual pattern of X-linked inheritance, because males are usually not or less severely affected than females. Previously, a CFNS locus has been localised in Xp22. We report on a haplotype analysis in a German CFNS family, mapping the CFNS locus to the pericentromeric region of the X chromosome. This discrepancy can be explained by locus heterogeneity. Furthermore, random X inactivation could be demonstrated in affected females. The most plausible interpretation for this unusual pattern of X-linked inheritance is metabolic interference. Consequently, we propose that the CFNS gene escapes X inactivation.

Expression pattern and further characterization of human MAGED2 and identification of rodent orthologues

In a search for genes involved in X-linked mental retardation we have analyzed the expression pattern and genomic structure of human MAGED2. This gene is a member of a new defined MAGE-D cluster in Xp11.2, a hot spot for X-linked mental retardation. Rat and mouse orthologues have been isolated. In contrast to the genes of the MAGE-A, MAGE- B and MAGE-C clusters, MAGED2 is expressed ubiquitously. High expression was detected in specific brain regions and in the interstitium of testes. Five SNPs in the coding region of human MAGED2 were characterized and their allele frequencies determined in a German and Turkish population.

High reliability and sensitivity of the BCR/ABL1 D-FISH test for the detection of BCR/ABL rearrangements

The BCR/ABL1 fusion gene is mainly caused by the t(9; 22)(q34; q11.2) translocation, which results in the Philadelphia (Ph) chromosome. The Ph chromosome is the typical hallmark in chronic myeloid leukemia (CML), but can also be present in acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). The BCR/ABL1 rearrangement is an important tumor classification marker and a useful prognostic factor allowing an adequate therapy management. Ph chromosome detection by conventional cytogenetics (CC) can be hampered by low quantity and quality of metaphases from tumor cells. Furthermore, BCR/ABL1 rearrangements may be hidden due to cryptic rearrangements or complex aberrations. Therefore, molecular cytogenetic methods turned out to be useful tools for the detection of BCR/ABL1 rearrangements. We performed fluorescent in situ hybridization (FISH) with the recently developed BCR/ABL1 D-FISH probe (QBIOgene, Illkirch, F) on cultured bone marrow and peripheral blood cells of 71 patients with CML, ALL, AML, and myeloproliferative disorder (MPD). FISH results and the results of banding methods were directly compared. Based on the analyses of >200 nuclei per patient, D-FISH correlated closely with CC and allowed an accurate quantification of BCR/ABL1 rearrangements even in a low percentage of aberrant cells. No false-positive or false-negative results were obtained. Furthermore, the D-FISH probe detected three cryptic and one complex BCR/ABL1 rearrangement, which were not visible by CC. We conclude that D-FISH reliably detects standard Ph chromosomes as well as its variant translocations and accurately quantifies BCR/ABL1 rearrangements prior and during cancer treatment as well as in the phase of remission, in daily routine tumor cytogenetic diagnostics.

Preferential inactivation of a dupX(q23 --> q27-28) chromosome in a girl with mental retardation and dysmorphy

We report on an 18-year-old female with de novo tandem duplication Xq23-->Xq27-28. The breakpoints of the duplication segment have been mapped by FISH using a panel of locus specific YACs. Despite selective inactivation of the aberrant X chromosome, proven by a combination of molecular and cytogenetic studies, the patient exhibits mental retardation, dysmorphic features and short stature. Possible mechanisms explaining this unexpected finding are discussed.

High frequency of spontaneous translocations revealed by FISH in cells from patients with the cancer-prone syndromes ataxia telangiectasia and Nijmegen breakage syndrome

The application of fluorescence in situ hybridization (FISH) using whole-chromosome paints (WCPs) is proving to be a very powerful technique for revealing chromosomal instability that, for the most part, has gone undetected by conventional cytogenetic analysis. We have analyzed the frequency of translocations in lymphocytes and lymphoblastoid cell lines from ataxia telangiectasia (AT) and Nijmegen breakage syndrome (NBS) homozygotes and heterozygotes using a three-color chromosome-painting technique (WCP 1, 2, 4). With this assay we were able to detect an increased frequency of spontaneous translocations in AT homozygotes (median, 18.47 +/- 10.82 translocations per 1,000 metaphase cells; 10 patients) and AT heterozygotes (median, 7.87 +/- 3.15 translocations per 1,000 cells; 7 patients), in comparison to controls (median, 2.26 +/- 1.75 translocations per 1,000 cells; 10 controls). Analysis of NBS homozygotes (median, 19.05 +/- 11.27 translocations per 1,000 cells; 5 patients) and NBS heterozygotes (median, 6.93 +/- 3.04 translocations per 1,000 cells; 6 patients) also showed an increased frequency of translocations in these patients compared to controls. The presence of such hitherto undetected chromosomal aberrations corroborate previous findings of spontaneous chromosomal instability in AT and NBS patients, as manifested by an increased rate of open breaks and rearrangements involving chromosomes 7 and 14. Moreover, we show that the degree of genomic instability in AT and NBS patients is even higher than previously established and that some AT and NBS heterozygotes evidence spontaneous chromosomal instability as well. These increased levels of nonspecific translocations could be an important risk factor for the development of malignancies in homozygotes and heterozygotes for ATM or NBS1 gene mutations.

Campomelic dysplasia without sex reversal in a Turkish patient is due to mutation Ala119Val within the SOX9 gene

Campomelic dysplasia is a rare neonatal skeletal malformation syndrome mainly characterized by congenital bowing and angulation of long bones in combination with other skeletal and extraskeletal defects. Two thirds of karyotypic males exhibit male-to-female sex reversal. Point mutations within SOX9 in 17q24-25 or rearrangements upstream to SOX9 as well as a deletion of a complete gene, causing haploinsufficiency of the gene product, have been detected in some patients. Recurrent mutations appear to be rare and most mutations detected in campomelic dysplasia are family specific. Here, we report on a Turkish patient with a 46,XY karyotype affected by campomelic dysplasia without sex reversal. Sequencing the SOX9 gene revealed a heterozygous Ala119Val mutation in exon 1, coding for the highly conserved HMG-box of the gene. This mutation is not present in the parents' lymphocyte DNAs. The same mutation was recently reported in a patient with 46,XX karyotype. Additionally, our patient is homozygous for the common polymorphism c507C-->T, while both parents are heterozygous.

Female pseudohermaphroditism caused by caudal dysgenesis

We report on two cases of female pseudohermaphroditism associated with anorectal, Müllerian duct, and urinary tract malformations. We suggest that this form of female pseudohermaphroditism is an extreme manifestation of the caudal type of VATER association.

No evidence for deletions of the NBS1 gene in lymphomas

Patients with Nijmegen breakage syndrome (NBS) have a high risk to develop malignant diseases, most frequently B-cell lymphomas. The NBS gene product, nibrin, is involved in DNA recombination repair, a function shared with known tumor suppressor genes like BRCA1 and BRCA2. This led us to investigate whether NBS acts as tumor suppressor gene in the development of non-Hodgkin lymphomas. Therefore, we performed fluorescence in situ hybridization analysis using a BAC clone containing the entire NBS1 region on eight B-cell and eight T-cell lymphomas, including one B-cell and two T-cell lymphomas with structural abnormalities of 8q. None of the tumors showed a deletion of the NBS1 gene, demonstrating that deletion of the NBS1 gene is not a major cause or a primary event in tumorigenesis of human B- and T-cell lymphomas.

Cloning of Z39Ig, a novel gene with immunoglobulin-like domains located on human chromosome X

The cDNA sequence and expression profile of a novel human gene, encoding a new member of the immunoglobulin superfamily, is reported. The gene is localized in the pericentromeric region of human X chromosome between the markers DXS1213 and DXS1194. Abundant expression of transcripts was detected in several human fetal tissues, whereas among adult tissues lung and placenta express highest levels of Z39Ig mRNA.

A novel translocation (17;19)(p13;p13) in a patient with acute myelomonocytic leukemia

We report on a patient with acute myeloid leukemia (AML M4) and a so far unrecorded translocation (17;19). The leukemia transformed from a myeloproliferative disorder (MPD) and showed a progressive fatal course. Following transformation, all leukemic cells showed an apparently balanced translocation (17;19)(p13;p13). The breakpoint regions harbor genes such as TP53 (17p13) and E2A, ENL, or LYL1 (19p13), which could be relevant in leukemogenesis. We suspect that the translocation (17;19)(p13;p13) may be a prognostic factor for transformation from chronic MPD to acute leukemia.