Opposite deletions/duplications of the X chromosome: two novel reciprocal rearrangements

Paralogous sequences on the same chromosome allow refolding of the chromosome into itself and homologous recombination. Recombinant chromosomes have microscopic or submicroscopic rearrangements according to the distance between repeats. Examples are the submicroscopic inversions of factor VIII, of the IDS gene and of the FLN1/emerin region, all resulting from misalignment of inverted repeats, and double recombination. Most of these inversions are of paternal origin possibly because the X chromosome at male meiosis is free to refold into itself for most of its length. We report on two de novo rearrangements of the X chromosome found in four hypogonadic females. Two of them had an X chromosome deleted for most of Xp and duplicated for a portion of Xq and two had the opposite rearrangement (class I and class II rearrangements, respectively). The breakpoints were defined at the level of contiguous YACs. The same Xp 11.23 breakpoint was found in the four cases. That of the long arm coincided in three cases (Xq21.3) and was more proximal in case 4 (Xq21.1). Thus class I rearrangements (cases 1 and 2) are reciprocal to that of case 3, whilst that of case 4 shares only the Xp breakpoint. The abnormal X was paternal in the three cases investigated. Repeated inverted sequences located at the breakpoints of rearrangements are likely to favour the refolding of the paternal X chromosome and the recombination of the repeats. The repeat at the Xp11 may synapse with either that at Xq21.3 or that at Xq21.1. These rearrangements seem to originate as the Xq28 submicroscopic inversions but they are identifiable at the microscopic level and result from a single recombination event.

[Orofaciodigital syndrome--a new variant? Psychiatric, neurologic and neuroradiological findings]

Oral-facial-digital (OFD) syndromes are a heterogeneous group of inherited syndromes that have in common anomalies of the face (median cleft lip), the tongue (bifid or lobulated tongue with harmartomas), and the digits (brachydactyly, polydactyly, syndactyly). Due to more or less subtle clinical features, at least seven causally different entities can be identified: 1) OFDS I; 2) OFDS II (Mohr syndrome); 3) OFDS III; 4) OFDS with tibial anomalies (OFDS IV); 5) OFDS V (Thurston syndrome); 6) OFDS VI (Váradi syndrome); and 7) OFDS VII (Whelan syndrome). The neuro-psychiatric clinical observations and MRI findings of a 40 year old woman with a OFD syndrome are described. The observed findings (leukoaraiosis, epilepsy, major depression) in combination with a proven OFD syndrome possibly reflect a new type of OFD syndrome.

New genetic, pathophysiologic, and therapeutic issues in nystagmus

Nystagmus may have onset in infancy or adulthood. Infantile-onset nystagmus is commonly associated with genetic disease, and recognition of the various genetic and nongenetic diseases in which it may develop has led to the understanding that nystagmus is often a response of the oculomotor system to an early-onset, bilateral abnormality of vision. Adult-onset nystagmus most often develops as a result of nongenetic neurologic disease, and it manifests in a variety of patterns. Genetic studies have allowed further identification of the genes and genetic loci associated with nystagmus, and careful eye-movement recordings in patients with various patterns of nystagmus have further clarified the oculomotor pathophysiology.

Detection of mutations in the COL4A5 gene in over 90% of male patients with X-linked Alport's syndrome by RT-PCR and direct sequencing

X-linked Alport's syndrome is caused by mutations in the COL4A5 gene encoding the type IV collagen alpha5 chain (alpha5[IV]). Polymerase chain reaction-single-str and conformation polymorphism (PCR-SSCP) on genomic DNA has previously been used to screen for mutations in the COL4A5 gene, but this method was relatively insensitive, with mutations detected in less than 50% of patients. Here, we report a systematic analysis of the entire coding region of the COL4A5 gene, using nested reverse-transcription-polymerase chain reaction (RT-PCR) and the direct sequence method using leukocytes. This study examines twenty-two unrelated Japanese patients with X-linked Alport's syndrome showing abnormal expression of alpha5(IV) in the glomerular or epidermal basement membranes. Mutations that were predicted to be pathogenic were identified in 12 of the 13 male patients (92%) and five of the nine female patients (56%). Six patients had missense mutations, four had out-of-frame deletion mutations, three had nonsense mutations, and three had mutations causing exon loss of the transcript. The current study shows that nested RT-PCR and the direct sequence method using leukocytes are highly sensitive and offer a useful approach for systematic gene analysis in patients with X-linked Alport's syndrome.

Severe haemophilia A in a female: a compound heterozygote with nonrandom X-inactivation

We report a case of severe haemophilia A (<1% factor VIII level) in a female resulting from an interesting and improbable combination of events. The patient inherited a factor VIII intron 22 inversion from her carrier mother, as well as a second factor VIII inversion involving intron 22 that arose de novo on her paternally derived X chromosome. In addition, the patient's paternally derived X chromosome had been preferentially inactivated in 95+% of her somatic cells. The patient's mother, who was clinically unaffected, carried an intron 22 inversion as well and also showed nonrandom X-inactivation. The patient's mother had a brother with severe haemophilia A. It is therefore likely that the mother's inversion was on her maternally derived X chromosome. Since she was unaffected, it is likely that her inversion-bearing X was the one that was preferentially inactivated.

[X chromosome dominant hereditary nephritis: characterization by pedigree analysis and simple studies in general practice]

A family with chronic renal disease in the Bernese Oberland (Switzerland) is described. Most family members were directly evaluated by the author. The clinical syndromes identified in different family members are quite variable, reaching from asymptomatic glomerular microhematuria to segmental sclerosing glomerulonephritis with end stage renal failure. Based on the observation of the pedigree over five generations, the disorder appears to be transmitted as an x-chromosomal dominant trait. Together with the ultrastructural diagnosis, the disorder corresponds to an Alport's syndrome Typ IV Atkien.

XX/XY chimerism and freemartinism in a female llama co-twin to a male

A 20-month-old female llama was examined because at the time of mating, the male llama was apparently unable to achieve intromission. The female llama had been born co-twin to a male. On physical examination, the vaginal vestibule appeared to end in a blind pouch, and the uterus, cervix, and ovaries could not be identified during transrectal palpation or ultrasonography. Karyotyping was done, and 43% of blood lymphocytes had 2 X chromosomes, and 57% had 1 X and 1 Y chromosome. All skin fibroblasts had 2 X chromosomes. A diagnosis of freemartinism and XX/XY chimerism was made. Because conception of twins may be more common in llamas than birth of twins, it is possible that freemartinism could develop in singleton females, if, for instance, a male twin was conceived and died after the placentas had anastomosed. More widespread use of karyotyping in llamas with congenital defects of the reproductive tract will help to define the incidence of freemartinism.

Diagnosing genetic anomalies by inspection

Several readily identifiable syndromes that have a genetic basis consist of mental retardation, hyperactivity or other abnormal behaviors, and characteristic physical signs. These disorders are not only an opportunity for clinical diagnosis, but they reflect the neurologic underpinning of intellect and behavior. Moreover, the wide variations in their phenotypes suggests that genetic testing be considered in children with abnormal appearance and mental retardation.

Somatosensory evoked potentials in X-linked recessive bulbospinal neuronopathy: a case demonstration

Clinicopathological findings in X-linked recessive bulbospinal neuronopathy were characterized by loss of myelinated fibers in the fasciculus gracilis and depletion of neurons in the ventral horn throughout the same segments. Clinical profile of this rare motor neuron disease include sign and symptom of lower motor neuron involving bulbar and spinal level with minimal or no sensory deficit. Previous electrodiagnostic findings consist of electrophysiological evidence of anterior horn cell disease and decreased or absent sensory action potentials in the peripheral nerve. The role of somatosensory evoked potential which can uncover the involvement of posterior column has never been probed. We report a 22-year-old man who had a clinical syndrome of X-linked bulbospinal neuronopathy. The peripheral electrodiagnostic studies supported the evidence of prolonged anterior horn cell disease and decreased sensory response. The median SEPs revealed delayed N11-N13 and N13-N20 interpeak latencies representing demyelination in fasciculus gracilis of upper cervical cord. Therefore, the median SEPs, an uninvasive procedure, can be used as a supportive method to identify sensory neuronopathy with posterior column lesion in this syndrome, especially when the patient has no obvious sensory and endocrine symptom.

Complete androgen insensitivity in a 47,XXY patient with uniparental disomy for the X chromosome

We describe a unique patient with complete androgen insensitivity syndrome and a 47,XXY karyotype. Androgen receptor assay using cultured pubic skin fibroblasts showed no androgen-binding capacity. Sequence analysis of the androgen receptor gene demonstrated two nonsense mutations, one in exon D and one in exon E. Microsatellite marker analysis showed that the patient is homozygous for all five Xq loci examined. The results suggest that the long-arms of the two X chromosomes are identical, i.e., uniparental isodisomy at least for Xq, and carry the same mutations in the androgen receptor gene. This explains how complete androgen insensitivity syndrome occurred in this 47,XXY individual.

Random X-inactivation in a girl with duplication Xp11.21-p21.3: report of a patient and review of the literature

We describe a 10-month-old girl with abnormal clinical findings and Xp duplication. She showed poor weight gain and developmental retardation, and had several minor anomalies including pigmentary dysplasia (hypomelanosis of Ito). She had a partial short arm duplication in the paternally derived X chromosome, 46,X,dup(X)(p11. 21p21.3), with the normal and duplicated X chromosomes randomly inactivated. These findings indicate that gross functional imbalance in the cells with an active dup(X) chromosome has caused global developmental defects in the patient, and that functional chromosomal mosaicism with respect to the duplicated Xp region has resulted in pigmentary dysplasia. Literature review of 52 patients with partial X duplications revealed (1) random or skewed but not completely selective X-inactivation in 9 of 45 patients examined for the X-inactivation pattern, independently of the size or location of duplicated segments, (2) apparently normal phenotype in 6 of 9 patients with random or skewed X-inactivation, and (3) an abnormal phenotype in 13 of 35 patients with completely selective inactivation of dup(X) chromosomes.

Pentasomy X and hyper IgE syndrome: co-existence of two distinct genetic disorders

We describe a 10-year-old girl with features of a penta-X syndrome. Cytogenetic analysis revealed a 49,XXXXX karyotype and molecular analysis of X-linked polymorphic markers showed that this aneuploidy arose by successive maternal non disjunctions. Apart from these features the patient has a lifelong history of eczema, recurrent pneumonia, and staphylococcal abscesses. Together with consistently increased serum IgE levels, low antibody responses, and low levels of serum IgA and IgG2, these findings are characteristic for the hyper IgE syndrome. While pentasomy X may be due to sequential non disjunctions in meiosis I and meiosis II in the mother, the underlying pathomechanism in hyper IgE syndrome remains unclear. This case is the first with co-existence of pentasomy X and hyper IgE syndromes.

[Pediatric mono-arthritis as initial manifestation of X-linked agammaglobulinemia (M. Bruton)]

INTRODUCTION

There are different causes for knee joint effusions in children. Rheumatoid diseases and hematogenous septic arthritis are the most important differential diagnoses. It is less known that immunodeficiency syndromes may cause serous monarthritis.

RESULTS

A case of a five years old boy with monarthritis of the knee is presented. Blood assay and specific immunologic analysis revealed a so far unknown X-linked agammaglobulinemia (M. Bruton).

CONCLUSIONS

In case of a monarthritis in children the orthopaedic surgeon or the pediatrician is primarily involved. For differential diagnosis X-linked agammaglobulinemia should be considered as reason for monarthritis, especially, if there are other clues to that disease in the medical history. In the case of agammaglobulinemia effusion and swelling will decrease soon after treatment with intravenous gammaglobulin.

Transmission of a Y chromosomal deletion involving the deleted in azoospermia (DAZ) and chromodomain (CDY1) genes from father to son through intracytoplasmic sperm injection: case report

The transmission of a deleted in azoospermia (DAZ) deletion from a severely oligozoospermic patient to his son following intracytoplasmic sperm injection (ICSI) treatment is reported. The case report highlights the fertilizing capacity of spermatozoa carrying Y chromosome deletions in patients treated with ICSI and stresses the importance of genetic counselling in severe male infertility.

[A case of neonatal 49,XXXXY syndrome]

The authors present the case of 49,XXXXY syndrome diagnosed in neonatal age. During the investigation of ambiguous genitalia was identified sex chromosome anomaly. The authors deal with possible pathogenesis of the syndrome and its clinical symptoms in details. They emphasize the importance of both testosterone substitution with pubertal timing, and early intellectual and social development.

Prenatal ultrasound detection of a congenital epulis in a triple X female fetus: a case report

A case of congenital epulis in a triple X infant, whose intra-oral mass was first detected on a 33-week prenatal ultrasound, is described. Two previous ultrasound studies performed at 21 and 28 weeks' gestation showed normal facial anatomy, suggesting accelerated tumour growth during the third trimester. Genetic amniocentesis also showed the infant to possess a 47, XXX karyotype.

Role of multicolor fluorescence in situ hybridization (FISH) in simultaneous detection of probe sets for chromosome 18, X and Y in uncultured amniotic fluid cells

Major aneuploidies diagnosed prenatally involve the autosomes 13, 18, and 21, and sex chromosomes. Fluorescence in situ hybridization (FISH) allows rapid analysis of chromosome copy number in interphase cells. The purpose of this study was to evaluate the role of multicolor fluorescence in situ hybridization in simultaneous detection of probe sets for chromosome 18, X, and Y in uncultured amniotic fluid cells as a safer alternative method for aneuploidy detection prenatally. Fifty amniotic fluid samples were analyzed by FISH and standard cytogenetics. Mean time to obtain results was three days for fluorescence in situ hybridization and 20 days for karyotype. Fluorescence in situ hybridization was informative in 43 samples (86%), and within this group, two aneuploidies were correctly identified. This evaluation demonstrates that FISH with X, Y, and 18 alpha satellite DNA probes could accurately and rapidly detect aneuploidies involving these chromosomes and could be used in any prenatal clinical laboratory.

Sex chromosome aneuploidies in sperm of 47,XYY men

The sex chromosomal equipment in 26,675 sperm of 47,XYY males was analyzed. A total of 5.78% of the nuclei exhibited sex chromosome hyperhaploidy. Six studies have analyzed the sperm of 10 XYY patients and, although these studies indicated some degree of elimination of the extra Y chromosome during spermatogenesis, a certain percentage of XYY germinal cells may also be able to achieve meiosis and produce sperm with gonosomal disomies. All these studies show an increased incidence of gonosomal aneuploidies in sperm, but there are significant discrepancies concerning the extent of these abnormalities. The global frequencies of sperm with an abnormal number of sex chromosomes ranged from 0.578 to 13.91%, depending on the patients. There are several explanations for these discrepancies: differences attributed to fluorescence in situ hybridization methodology, the use of dual or multicolor FISH, recruitment, interindividual variations, and intraindividual variations. This study reports an additional series obtained from another XYY individual and compares and discusses the data on gonosomal hyperhaploidies in sperm of 47 XYY males using in situ hybridization analyses.

Criminality and antisocial behaviour in unselected men with sex chromosome abnormalities

BACKGROUND

Previous studies on male patients with sex chromosome abnormalities (SCA), namely XYY and XXY, suggest that such patients commit criminal acts more frequently than expected. Most of these studies are affected by ascertainment bias.

METHODS

Using a population-based sample of men with SCA, identified by screening 34380 infants at birth between 1967 and 1979, comparison between 16 XYY men, 13 XXY men and 45 controls were made in terms of frequency of antisocial personality disorder (APD) using the Schedule for Affective Disorders and Schizophrenia lifetime version. Rates of criminal convictions were examined in 17 XYY men, 17 XXY men and 60 controls.

RESULTS

XYY males showed a significantly higher frequency of antisocial behaviour in adolescence and adulthood and of criminal convictions than the controls, but multiple regression analysis showed this to be mediated mainly through lowered intelligence. Property offences constituted the majority of offences in all groups. The XXY men did not show an increased rate of criminal convictions. It is possible that this apparently negative result relates to the relatively small numbers of cases and hence low power of this study.

CONCLUSIONS

The findings of this study carry the advantage of not being affected by ascertainment bias and the disadvantage of having low power. It provides evidence for a slightly increased liability to antisocial behaviour in XYY men.

Early onset of X-linked Emery-Dreifuss muscular dystrophy in a boy with emerin gene deletion

A boy developed contractures of the Achilles tendons at 3 years and of the postcervical muscles at 7 years, although neither contractures of the elbows nor cardiac abnormality were recognized by the age of 9 years. Muscle computed tomography scanning revealed changes characteristic of muscle involvement. Emerin was not detected in the biopsied muscle, and RT-PCR and PCR-based genomic DNA analyses of the emerin gene demonstrated no amplification product in the patient. These results confirmed the diagnosis of X-linked Emery-Dreifuss muscular dystrophy (EDMD), and reinforce the necessity of molecular genetic diagnosis of the membrane protein emerin in younger patients with possible EDMD before appearance of the typical symptoms, to avoid sudden cardiac death.