Prenatal diagnosis and genetic analysis of X chromosome polysomy 49, XXXXY

We report on the prenatal diagnosis, genetic analysis and clinical manifestations of a 49,XXXXY fetus. A 31-year-old, primigravida woman was referred for genetic counselling at 17 weeks' gestation with the sonographic findings of intrauterine growth retardation, generalized oedema, a large septated cystic hygroma colli measuring 5x4 cm, and abnormal posturing of the lower extremities. Quantitative fluorescent polymerase chain reaction (QF-PCR) with small tandem repeat (STR) markers specific for chromosome X and a pentanucleotide marker X22 for the Xq/Yq pseudoautosomal region PAR2 rapidly detected the X-chromosome polysomy from amniotic fluid cells. This abnormality appeared to arise from successive non-disjunction during maternal meiosis I and meiosis II. Cytogenetic analysis revealed a karyotype of 49,XXXXY. Our case shows that a 49,XXXXY fetus in the second trimester may demonstrate hydrops fetalis and a large septated cystic hygroma colli by prenatal ultrasound. Our case also shows that QF-PCR assays with sex chromosome specific STR markers provide rapid prenatal diagnosis of numerical sex chromosome aneuploidy as well as its genetic cause in fetal cystic hygroma.

Infertility and multiple urogenital abnormalities in a male with mosaic 46,XY/45,XO/47,XXY karyotype and mixed phenotype

We hereby present a rare case of a 46,XY/45,XO/47,XXY mosaic male patient with a predominance of the XY cell line. The patient, who exhibited phenotypic stigmata of both XO gonadal dysgenesis and Klinefelter syndromes, suffered from infertility and multiple urogenital abnormalities, as our investigation revealed.

[Investigation of fetal cells isolated from maternal blood by different methods]

This paper presents the results of investigation of the isolated from maternal blood by 4 different methods according to the optimized protocols. All women had male fetuses. The mononuclear cells with fetal erythroblasts were preisolated by using density-gradient centrifugation of the maternal blood in the Ficoll solution. Fetal cells were detected by FISH for Y-chromosomal sequences. The fetal cells were 2.1% by fluorescence activated cell sorting (FACS); 3.8% by magnetic field sorting, and 2.6% by two-stage density gradient precipitation. The fetal lymphocytes were investigated through air-cultivation of peripheral maternal lymphocytes. Their proportion was 3.9% in the culture samples. The findings lead to the conclusion that the new non-invasive approach is useful for prenatal diagnosis of chromosomal aneuploidies.

Hereditary cyclic neutropenia in the male members of a Chinese family with inverted Y chromosome

We describe four male members of a Chinese family, including the father and three sons, with hereditary cyclic neutropenia. These patients had all developed cyclic neutropenia in childhood with a cycle of around 21 d. Recurrent mucosa and skin infections with fever had occurred frequently, but gradually decreased in severity on reaching adulthood. Monocytosis was found during the neutrophil nadirs in all four patients. Mildly increased serum immunoglobulin (Ig)A and IgG levels, low levels of serum stem cell factor, as well as decreased sperm count and motility were demonstrated in the two elder sons. Chromosomal analysis showed a pericentric inversion of Y chromosome [46,X, inv(Y)(p11.2;q11.23)] in all of the men. These findings may suggest an association between cyclic neutropenia with oligospermia and inv(Y)(p11.2;q11.23) in this particular family.

[Development of an original computer program FISHMet: use for molecular cytogenetic diagnosis and genome mapping by fluorescent in situ hybridization (FISH)]

Original software FISHMet has been developed and tried for improving the efficiency of diagnosis of hereditary diseases caused by chromosome aberrations and for chromosome mapping by fluorescent in situ hybridization (FISH) method. The program allows creation and analysis of pseudocolor chromosome images and hybridization signals in the Windows 95 system, allows computer analysis and editing of the results of pseudocolor hybridization in situ, including successive imposition of initial black-and-white images created using fluorescent filters (blue, green, and red), and editing of each image individually or of a summary pseudocolor image in BMP, TIFF, and JPEG formats. Components of image computer analysis system (LOMO, Leitz Ortoplan, and Axioplan fluorescent microscopes, COHU 4910 and Sanyo VCB-3512P CCD cameras, Miro-Video, Scion LG-3 and VG-5 image capture maps, and Pentium 100 and Pentium 200 computers) and specialized software for image capture and visualization (Scion Image PC and Video-Cup) have been used with good results in the study.

Molecular cytogenetic analysis of a duplication Xp in a female with an abnormal phenotype and random X inactivation

We describe a female infant with severe abnormal phenotype with a de novo partial duplication of the short arm of the X chromosome. Chromosome painting confirmed the origin of this X duplication. Molecular cytogenetic analysis with fluorescence in situ hybridization (FISH) was performed with YAC probes, further delineating the breakpoints. The karyotype was 46, X dup(X)(p11-p21.2). Cytogenetic replication studies showed that the normal and duplicated X chromosomes were randomly inactivated in lymphocytes. In most females with structurally abnormal X chromosomes, the abnormal chromosome is inactivated and they are phenotypically apparently normal relatives of phenotypically abnormal males having dupX. Therefore, in this case, there is functional disomy of Xp11-p21.2 in the cells with an active dup(X), most likely resulting in abnormal clinical findings in the patient.

First trimester maternal serum AFP and total hCG in aneuploidies other than trisomy 21

Total human chorionic gonadotropin (hCG) and alpha-fetoprotein (AFP) were measured in maternal serum at 10-14 weeks of gestation from 53 pregnancies affected by trisomy 18, 42 cases with trisomy 13, 46 with Turner's syndrome and 13 with other sex aneuploides. The only significant association was the finding of reduced levels of total hCG in cases of trisomy 18 and 13. The association of increased levels of AFP in cases of trisomy 18 with ventral wall defects and the slight increase in AFP in cases of sex chromosomal anomalies other than Turner's syndrome was found. AFP and total hCG are not likely to replace the markers free beta-hCG and PAPP-A in first trimester screening for chromosomal anomalies.

[Microdeletion of Y chromosome in severe olygozoospemic infertile patient]

We are reporting a 37 year old male with severe oligozoospermia and a history of infertility for thirteen years and surgery for severe unilateral varicocele. The hormonal levels for FSH, LH and T, and karyotype were within the normal range. Multiplex PCR revealed the presence of a de novo microdeletion in the azoospermia factor (AZF) c region involving the deleted in azoospermia (DAZ) and basic protein Y-2 (BPY2) genes. These results suggest that severe oligozoospermia should be considered for the screening of microdeletions of Yq involving the AZFc region even in the presence of a varicocele.

[Lipoprotein and apolipoprotein electrophoresis in X-chromosome recessive ichthyosis]

BACKGROUND AND OBJECTIVE

The clinical differentiation of the hereditary ichthyosis forms is difficult and without laboratory markers hardly possible. Serum lipoprotein electrophoresis is one tool for detecting patients with recessive X-linked ichthyosis (XRI). Compared to controls, XRI patients show elevated electrophoretic mobilities of low density (LDL) and very low density lipoproteins (VLDL). This change in pattern is only partially explained by the increased LDL cholesterin sulfate concentration and is the subject of this study.

PATIENTS/METHODS

Patients suffering from XRI and ichthyosis vulgaris, healthy controls. SDS-PAGE-electrophoresis and isoelectric focusing for detection of XRI-associated variations in apolipoproteins apo B-100, apo C-III and apo E.

RESULTS

XRI-associated apolipoprotein variants were not found. In contrast to the literature, an increased electrophoretic mobility was also observed for HDL (high density lipoproteins) from XRI patients.

CONCLUSIONS

The underlying cause of the increased electrophoretic mobility of VLDL and HDL in XRI patients remains unclear. Future studies should investigate other apolipoproteins and verify the cholesterin sulfate concentrations reported for VLDL and HDL from XRI patients.

Evaluation of the norrie disease gene in a family with incontinentia pigmenti

Incontinentia pigmenti (IP) is an ectodermal multisystem disorder which can affect dental, ocular, cardiac and neurologic structures. The ocular changes of IP can have a very similar appearance to the retinal detachment of X-linked familial exudative vitreoretinopathy, which has been shown to be caused by the mutations in the Norrie disease gene. Therefore, it is of interest to determine whether similar mutations in the gene can account for the retinal pathology in patients with IP. To test our hypothesis, we have analyzed the entire Norrie disease gene for a family with IP, by single strand conformational polymorphism followed by DNA sequencing. The sequencing data revealed no disease-specific sequence alterations. These data suggest that ocular findings of IP are perhaps associated with different genes and there is no direct relationship between the genotype and phenotype.

[Analysis of sperm aneuploidy in infertile subjects after chemotherapy treatment]

The continuing search for a cure for cancer has developed more aggressive therapies that may damage germ cells, leading to clinical disease in offspring of survivors. Standard therapy for the majority of cancer today consists in combinations of high doses of radiation and chemotherapy drugs. We investigated the effect of cancer treatments on the reproductive potential of men. Multicolor fluorescence in situ hybridization has been used to recognize chromosomes X, Y and 8 in sperm of 10 severely oligozoospermic subjects (sperm concentration < 5,000,000/mL) treated for cancer at least 5 years before the beginning of this study. As controls, we analyzed sperm aneuploidies in 20 fertile men (sperm concentration > 20,000,000/mL) and in 20 severe idiopathic oligozoospermic subjects (sperm concentration < 5,000,000/mL). In all subjects, X- and Y-bearing spermatozoa were present in a normal 1:1 ratio; nevertheless the frequency of 24,XY, 24,XX and 24,YY disomic sperm was significantly higher in patients treated for cancer and in idiopathic oligozoospermic subjects with respect to normozoospermic men. These results suggest that the increase in sperm aneuploidies in treated patients cannot be reported directly to precedent chemotherapy, but reflects the alteration of testicular structure, as in the case of severe idiopathic oligozoospermic subjects. With the advent of intra-cytoplasmic sperm injection, it is possible to offer the opportunity to conceive in men affected by severe oligozoospermia but it is also possible, when the spermatozoa of these subjects are used, to pass sex chromosome abnormalities on to the children. We therefore suggest caution before application of an artificial reproductive technique in severe oligozoospermic patients.

Investigation of a candidate gene for schizophrenia on Xq13 previously associated with mental retardation and hypothyroidism

Weak support for linkage of schizophrenia to proximal Xq has previously been reported. In addition, an increased prevalence of thyroid disorder has been noted in families of individuals with schizophrenia. Recently, a gene mapped to Xq13 termed HOPA has been found to be associated with mental retardation, hypothyroidism, and depression and to function as a coactivator for the thyroid receptor. We therefore examined the HOPA gene in a group of 111 probands from a larger cohort of multiplex families with schizophrenia, several of whom (n = 53) also had a family history of hypothyroidism. Four males and two females were found with an alteration in exon 42 of the HOPA gene compared with 8/492 males and 18/471 females (942 X chromosomes) compared with consecutively screened newborns (chi(2) = 3.92, P < 0.05). However, when available family members of each of the probands with an exon 42 variation were subsequently screened, the mutation did not segregate with schizophrenia in three of five families, although all 6 probands with an exon 42 variation did have hypothyroidism in either themselves (n = 3) or their mothers (n = 3) (P < 0.008). These findings replicate prior findings demonstrating an association between HOPA polymorphisms and hypothyroidism. In addition, the increased frequency of HOPA variants in this population may also provide a genetic basis for the familial association of thyroid disease and schizophrenia.

Current understanding of androgenetic alopecia. Part I: etiopathogenesis

Androgenetic alopecia (AGA) is the most common type of hair loss in men and women. This continuous process results in a type of alopecia that follows a definite pattern in those individuals who are genetically predisposed. At present the predisposing genes are unknown but the relatively strong concordance of the degree of baldness in fathers and sons is not consistent with a simple Mendelian trait and a polygenic basis is therefore most likely. AGA can be defined as a DHT-dependent process with continuous miniaturization of sensitive HF. Today we do not understand the molecular steps involved in androgen-dependent beard growth versus androgen-dependent hair loss in AGA. However, recent experimental and clinical advances enable us to explain some pathogenetic steps leading to androgenetic hair loss. Among other steroidogenic isoenzymes such as 17b- and 3b- hydroxysteroid dehydrogenases, the type 2 5a-reductase within the dermal papilla plays a central role by the intrafollicular conversion of T to DHT.

Characterization of a highly complex region in Xq13 and mapping of three isodicentric breakpoints associated with preleukemia

The chromosomal abnormality represented by an isodicentric X chromosome [idic(X)(q13)] is associated with a subset of acute myeloid leukemia (AML) and preleukemia observed in elderly females. A previous study localized the breakpoints of two acquired isodicentric X chromosomes associated with myelodysplasia to a 450-kb region proximal to the XIST gene. Here we report the construction and extensive characterization of a reliable 1-Mb P1 artificial chromosome and bacterial artificial chromosome contig covering a highly problematic region in Xq13 that includes the previously described isodicentric breakpoint region. In addition to mapping of the brain-specific gene (NAP1L2) and the phosphoglyceryl kinase alpha subunit 1 gene (PHKA1) and generation and mapping of a large number of STSs throughout the contig, we have mapped a putative transcriptional regulatory protein (HDACL1), and 35 ESTs. Sequencing data, Southern blot analysis, and fiber-FISH analysis have permitted characterization of extensive region-specific duplications and triplications in addition to an unusually high concentration of long interspersed repeat elements, both of which could be implicated in isodicentric chromosome formation and other Xq13 chromosome aberrations. FISH analysis of metaphase chromosomes from two previously unpublished AML patients and one preleukemic patient using cosmid clones and selected subclones allowed mapping of the idic(X)(q13) breakpoints to a 100-kb interval, consistent with the involvement of an X-linked gene in the genesis of this form of preleukemia, disruption of which may represent a preliminary step in progression to AML. Assembly and physical mapping of this complex 1-Mb contig establish a foundation for ongoing sequencing and gene identification projects in the region.

[Boy or girl? Molecular mechanisms in sex differentiation]

A growing number of factors have been recognized as crucial in sexual development, and many clinical conditions have become understandable as mutations in relevant genes have been identified. In some cases this has led to the development of DNA diagnostics, which can be of some aid in the workup of this type of patient. So far it is mainly more serious disorders which have been elucidated, thanks to the identification of extensive mutations in the key genes for sexual development. Exactly to what extent less severe damage in these genes underlies more subtle disorders of sexual development, such as disturbances in pubertal development and diminished fertility, is with few exceptions unknown. We are still aware of only a fraction of the information hidden in our genetic heritage. Developments in this field are nonetheless rapid, and molecular analyses will probably become more and more part and parcel of the workup of patients with a wide variety of disturbances in sexual development.

Antenatal diagnosis of subependymal heterotopia

Subependymal heterotopia consist of gray matter nodules along the lateral ventricular walls and are associated with epilepsy and other cerebral malformations. Some cases have an X-linked inheritance, and early antenatal diagnosis of affected fetuses is important for appropriate management. We present a case of heterotopia diagnosed by sonography and MR imaging at 23 weeks' gestation and discuss the differential diagnosis, reviewing the evolution and imaging appearances of the germinal matrix and its implications for detection of heterotopia.

[Diagnosis of aneuploidy with fluorescence in situ hybridization (FISH); value in pregnancies with increased risk for chromosome aberrations]

BACKGROUND

In the case of abnormal ultrasound findings, abnormal serum-screening and age-risk in advanced pregnancy a rapid diagnosis or exclusion of a chromosomal aneuploidy of the fetus is of great value for the clinical management. With fluorescence in situ hybridization (FISH) on uncultured amniotic fluid cells the detection of the most common aneuploidies, which account for about 2/3 of all chromosomal aberrations [1], is possible within 24 hours. The aim was to evaluate if the FISH-technique in combination with karyotyping after cell culturing could replace other methods like diagnostics form umbilical cord blood or placental biopsies.

MATERIALS AND METHODS

For the FISH assays commercially available directly with fluorochromes labelled DNA-probes (Vysis, Stuttgart) were used. FISH assays were performed on amniotic fluid samples from pregnancies at risk for fetal chromosome aberrations parallel to standard cytogenetic analysis. The method was performed on 230 samples of amniotic fluid. We tried to optimize the method concerning preparation of the cell material, the denaturation- and hybridization-steps and well as stringency of post-hybridization washes.

RESULTS

All trisomies 13, 18, 21 and the sex chromosome aneuploidies (n = 34) which were diagnosed by conventional cytogenetics were identified correctly by FISH analysis with the exception of one case of trisomy 21 mosaicism, in which hybridization failed. As structural chromosome aberrations and mosaicisms cannot be detected with this method, six additional chromosome aberrations were identified exclusively by cytogenetic analysis. The mean frequency of nuclei with abnormal signal pattern in the aneuploid cases was 89%. A minimum of 50 nuclei for each DNA-probe could be counted in 86% of the samples. The results of 12 cases were classified as uninformative, because only less than 15 hybridized nuclei or no hybridization signals could be scored. Maternal contamination was found in 17.4% of the samples.

CONCLUSIONS

In clinical cases with a high risk for an abnormal fetal karyotype and the need of quick clinical consequences, methods which make possible a karyotyping within shortest time should be preferred to amniocentesis and FISH-analysis, because Chromosomal mosaicism and structural aberrations, which represent up to 20% of all chromosomal abnormalities in this group, cannot be detected, uninformative cases can occur in up to 15% of all investigated samples and There is a risk for false-negative results through contamination of the sample with cells of maternal origin. In comparison with methods which permit rapid karyotyping from umbilical cord blood or placental biopsies, a delay in the diagnostic procedure has to be accepted, when the result of the FISH-analysis has to be confirmed by cell culturing and standard cytogenetic analysis.

Syndrome of microcephaly, mental retardation, and tracheoesophageal fistula associated with features of Rett syndrome

We report a 12-year-old girl with features of the syndrome of microcephaly, mesobrachydactyly, and tracheoesophageal fistula, who also developed distinctive features of Rett syndrome including regression of milestones with repetitive actions, autistic-like behavior, stereotypic hand movements, and seizures. This unique combination of clinical manifestations appears to constitute a "new syndrome." We speculate that this association may represent a contiguous gene syndrome.

An SRY-negative XX male with Huriez syndrome

This report studies a 42-year-old 46,XX patient affected by palmoplantar keratoderma. clinically classified as Huriez syndrome. The patient showed a male phenotype with apparently normal male features including testicular development. Cytogenetic and chromosomal painting analysis excluded the presence of translocation of the Y chromosome. PCR analysis of genomic DNA failed to detect the presence of the testis-determining gene, SRY. The presence of other Y-chromosome genes, known to be involved in testicular maturation and spermatogenesis, has also been analyzed. The data suggest that the sex reversal in this 46,XX male patient is due to a defect on a yet unidentified autosomal or X-linked sex-determining gene. The relationship between the sex reversion and the presence of sclerotylosis is discussed.

Intracytoplasmic sperm injection: what are the risks?

Intracytoplasmic sperm injection, a relatively new technique used at the time of in vitro fertilization to fertilize human oocytes, has provided couples with very severe male factor infertility the ability to conceive their own biologic children. Many men with severe oligospermia or azoospermia can now pass their genes on to their progeny, an event that might not have been possible for them just a few years ago. Recent studies now suggest that there may be genetic and developmental differences in some children conceived through intracytoplasmic sperm injection. It is likely that genetic testing and counseling will be recommended for all couples with male factor infertility in the near future.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader will be able to describe the various indications for the use of ICSI in the treatment of infertility, to identify the potential long-term risks associated with the use of ICSI, and to estimate the rate of chromosomal abnormalities in this population of infertile patients.

Genetic basis of male fertility

We are in the age of genetic discovery. Now the human genome has been completely sequenced1, there will be increasing understanding and ability to manipulate biochemical pathways downstream of genes. At the same time, further development of in vitro fertilization (IVF) and intracytoplasmic sperm injection(ICSI) will enable procreation in situations that were formerly impossible and when there may be an increased possibility of genetic abnormality. Furthermore, preimplantation diagnosis will enable defects to be diagnosed and will give the opportunity for the couple to decide whether to continue with treatment towards a pregnancy or not. Thus, there is a need for clinicians to have a good knowledge of the gentics and hereditary aspects of male (and indeed female) infertility and for couples to have access to correct information and expert counselling. Also, there are ethical implications of these scientific and clinical advances for the future child, the individual, the couple and society. There is increasing public unease about this new science of reproduction and, in the UK, there is regulation by law; thus, there is a need for clinicians and scientists to give accurate information in everday language to the public.

New insights into the genetic basis of intellectual disabilities

BACKGROUND

Within general practice patients with intellectual disabilities are common.

OBJECTIVE

This article sheds some new light on the underlying genetic mechanisms of intellectual disabilities. It outlines the genetic basis of known inherited and sporadic causes that have recently been understood through new molecular advances.

DISCUSSION

General practice has an important role to play in pursuing a precise biomedical diagnosis by improving information provided to the patient and family regarding recurrence risks and prognoses as well as management issues specific to the underlying condition. New molecular techniques are providing us with specific diagnostic tools as well as improving our understanding of the complex mechanisms that contribute to what is known as human intelligence.