Association of intrauterine growth retardation with monosomy of the terminal segment of the short arm of the X chromosome in patients with Turner's syndrome

Short stature, which may be a result of intrauterine growth retardation (IUGR), is a characteristic of Turner's syndrome. However, the loci responsible for IUGR have not been well studied. We reviewed the birth records of 74 patients with Turner's syndrome: 20 with pure X monosomy, 44 with X-mosaicisms, and 10 with X-structural abnormalities. The overall incidence of IUGR was 39.2% (29 of 74 patients). The SHOX gene is encoded in a terminal segment of the short arm of the X chromosome. In 39 patients where two copies of the SHOX gene were absent, the incidence of IUGR was 46.2% (18 of 39 patients). In 14 patients with two copies of the SHOX gene, the incidence of IUGR was significantly lower at 7.1% (1 of 14 patients). Our results suggest that SHOX influences in utero growth in Turner's syndrome.

Psychological assessment in XLMR: a proposal for setting international standards

The need for an agreed upon set of standards for assessing individuals with XLMR was made quite evident this past year at the Fragile X and XLMR Workshop in Strasbourg. Several affected individuals from different families may have been incorrectly diagnosed as MR. Many factors can have a negative affect on IQ testing. As a result, evaluating individuals with cognitive deficits can be problematic. To be effective, psychological assessments must produce uniform results that are consistent with the definition of MR. Therefore, to foster international research in XLMR. I propose a two-stage standardized protocol. To determine which tests may be suitable. I review an assortment of instruments for psychological assessment at each stage, noting their strengths and weaknesses. Afterward, I present a set of standardized protocols based on age and language ability.

Osteopathia striata with cranial sclerosis: literature reappraisal argues for X-linked inheritance

Osteopathia striata with cranial sclerosis (OS-CS) is characterized by linear striations of tubular bones and fan-shaped configurations of the ilia. Although referred in literature as an autosomal dominant disorder the clinical pattern of partial involvement as well as the reported family observations plead for X-linked inheritance with mild striated bone affections in carrier women and severe syndromic morbidity and high mortality in the males. Sporadic affected males are probably somatic mosaics. There is no proven father-son transmission. Symptomatic osteopathia striata (OS) is characteristic in X-linked focal dermal hypoplasia Goltz-Gorlin.

47,XXX male: A clinical and molecular study

We report a 53-year-old Japanese male with a 47,XXX karyotype. His clinical features included hypoplastic scrotal testes (4 ml bilaterally), normally formed small penis (3.8 cm), relatively poor pubic hair development (Tanner stage 3), gynecomastia, age-appropriate male height (159.1 cm), and mental retardation (verbal IQ of 56). Serum testosterone was markedly reduced (0.6 nmol/L). A needle biopsy showed severe testicular degeneration. FISH analysis revealed complex mosaicism consisting of (1) 47,XXX cells with a single copy of SRY (n = 177), two copies of SRY (n = 3), and no SRY (n = 1); (2) 46,XX cells with a single copy of SRY (n = 9) and no SRY (n = 3); (3) 45,X cells with no SRY (n = 5); and (4) 48,XXXX cells with a single copy of SRY (n = 1) and two copies of SRY (n = 1). PCR analysis showed the presence of Yp portion with the breakpoint between DYS264 and AMELY. Microsatellite analysis demonstrated three alleles for DMD and AR. X-inactivation analysis for the methylation status of the AR gene showed random inactivation of the three X chromosomes. The results suggest that this 47,XXX male has resulted from abnormal X-Y interchange during paternal meiosis and X-X nondisjunction during maternal meiosis. Complex mosaicism may be due to the age-related increase in mitotic nondisjunction which is prone to occur in rapidly dividing lymphocytes and to the presence of two randomly inactivated X chromosomes which may behave asynchronously during mitosis, and clinical features of this male would primarily be explained by the genetic information on the SRY (+) der(X) chromosome and his advanced age.

Tall stature, gonadal dysgenesis, and stigmata of Turner's syndrome caused by a structurally altered X chromosome

Genetic analysis in a tall 14-year-old girl with gonadal dysgenesis and some stigmata of Turner's syndrome revealed a duplication of the short arm in a monocentric X chromosome with partial loss of Xq. We suggest that triple gene dosage of SHOX and estrogen deficiency caused the unique overgrowth.

MRI and proton spectroscopy in Lowe syndrome

The oculocerebrorenal syndrome of Lowe (OCRL) is an X-linked disorder characterized by major abnormalities of eyes, nervous system, and kidneys. We report two patients with typical intracranial lesions on MRI. The proton spectroscopy study of the periventricular white matter showed a moderate elevation of the signal at 3.56 ppm in the patient with cystic lesions. This resonance is usually assigned to myo-inositol and interpreted as a glial marker. In our patient it could also represent a true accumulation inside the cysts of phosphatidylinositol 4,5-biphosphate which is not degraded in patients with Lowe syndrome.

Increased incidence of numerical chromosome abnormalities in spermatozoa injected into human oocytes by ICSI

The potential risk of transmitting chromosomally abnormal spermatozoa from infertile males into oocytes through intracytoplasmic sperm injection (ICSI) has prompted us to investigate the male pronuclei of tripronuclear zygotes (3PN) obtained after ICSI. To specify the type of anomalies, we used triple colour fluorescent in-situ hybridization (FISH) with three specific probes for chromosomes X, Y and 18. From a total of 163 paternal complements of ICSI-3PN zygotes, 90 (55.2%) had Y-chromosome signals. Eighty-three of these were normal, four had the disomy XY and three were diploid. In the remaining 73 ICSI-3PN zygotes without Y-chromosome signals, the origin of paternal pronuclei was extrapolated through chromosome constitution of the first polar body. Five anomalies were found in this group of zygotes, giving a total rate of numerical chromosome aberrations for fertilizing spermatozoa of 7.4%. In contrast to ICSI, only two disomies (1.5%) were found in the control group of IVF-3PN zygotes. Compared with the incidence of chromosome anomalies between paternal-derived pronuclei of ICSI- and IVF-3PN zygotes, the difference was statistically significant (P < 0.025). This study provides the first direct evidence of a higher incidence of numerical chromosome anomalies in sperm-fertilized human oocytes after ICSI.

A case of ambiguous genitalia presenting with a 45,X/46,Xr(Y)(p11.2;q11.23)/47,X,idic(Y)(p11.2),idic(Y)(p11.2) karyotype

An infant with ambiguous genitalia was found to have a karyotype 45,X/46,X,r(Y)(p11.2;q11.23)/47,X,idic(Y)(p11.2),idic(Y)(p11.2) using G-banding, C-banding and FISH. Examination of the genitalia revealed a phallus measuring 1.5 cm in length and 0.5 cm wide with perineal orifice. Subtle phenotypic features consistent with Turner syndrome were not present. Genital ultrasonography revealed the presence of an infantile uterus. Endoscopy of the vagina, uterus and cervix appeared normal.

Maternally inherited hypertrophic cardiomyopathy: a manifestation of mitochondrial DNA mutations--clinical course in two families

In the past decade, maternally inherited disorders have been described manifesting as hypertrophic cardiomyopathy. These are primarily associated with defects in oxidative metabolism due to an alteration in mitochondrial DNA. Although the biochemistry and molecular biology is well-defined, there is little information regarding clinical presentation and course. Reported manifestations can be broad and can include myopathy, encephalopathy, stroke-like episodes, hearing loss, cardiomyopathy, multiorgan dysfunction and sudden death. Predominant or exclusive involvement of the heart is rare. We report the clinical presentations, investigations, pathologic findings, and clinical course in two families with two mitochondrial tRNA defects with exclusive cardiac involvement and demonstrable clinical heterogeneity based on the percentage of mutant tRNA.

[Mitochondrial medicine for internists]

Human mitochondrial DNA (mtDNA) is a small, circular molecule, encoding for the translational machinery of the mitochondrion, as well as for 13 structural proteins that are all subunits of the respiratory chain. Point mutations, deletions, and copy-number variations are now functionally and genetically linked to human disease. Despite the fact that mtDNA is solely transmitted from the mother to the offspring, e.g. is maternally inherited, some mutations may occur spontaneously or may be acquired due to defects in nuclear DNA, e.g. are inherited in a mendelian fashion. The internist encounters predominantly myopathies, cardiomyopathies, lactic acidosis or diabetes mellitus but mtDNA-changes are also present with neurologic, hematologic and renal symptoms. Acquired mtDNA alterations are responsible for important drug side effects, such as ifosfamide, carboplatin, doxorubicin or nucleoside-analog reverse-transcriptase inhibitors. A specific mtDNA point-mutation predisposes to aminoglycoside-induced sensorineural deafness.

Detection of a novel mutation in X-linked amelogenesis imperfecta

Amelogenesis imperfecta (AI) is a heterogeneous group of inherited disorders of defective enamel formation. The major protein involved in enamel formation, amelogenin, is encoded by a gene located at Xp22.1-Xp22.3. This study investigated the molecular defect producing a combined phenotype of hypoplasia and hypomineralization in a family with the clinical features and inheritance pattern of X-linked amelogenesis imperfecta (XAI). Genomic DNA was prepared from buccal cells sampled from family members. The DNA was subjected to the polymerase chain-reaction (PCR) in the presence of a series of oligonucleotide primers designed to amplify all 7 exons of the amelogenin gene. Cloning and sequencing of the purified amplification products identified a cytosine deletion in exon VI at codon 119. The deletion resulted in a frameshift mutation, introducing a premature stop signal at codon 126, producing a truncated protein lacking the terminal 18 amino acids. Identifying mutations assists our understanding of the important functional domains within the gene, and finding another novel mutation emphasizes the need for family-specific diagnosis of amelogenesis imperfecta.

Exact sequential tests for single samples of discrete responses using spending functions

Sequential tests are increasingly used to reduce the expected sample size of trials in medical research. The majority of such methods are based on the assumption of normality for test statistics. In clinical trials yielding a single sample of discrete data, that assumption is often poorly satisfied. In this paper we show how a novel application of the spending function approach of Lan and DeMets can be used together with exact calculation methods to design sequential procedures for a single sample of discrete random variables without the assumption of normality. A special case is that of binomial data and the paper is illustrated by the design of a cytogenetic study which motivated this work.

Lack of association of the Norrie disease gene with retinoschisis phenotype

PURPOSE

It has been reported recently that mice carrying a disrupted Norrie disease gene produced alterations in the murine eye that are similar to congenital retinoschisis. Therefore, it was of interest to determine whether mutations in the Norrie disease gene can account for the disease in families with retinoschisis that do not carry mutations in the retinoschisis gene.

METHODS

The patient set comprised 5 cases of retinoschisis (1 familial and 4 sporadic), all unrelated to each other. Fundus examination of affected individuals showed foveal and peripheral schisis, and the visual acuity range was 20/40-20/60. Peripheral blood specimens were collected from affected and unaffected family members. DNA was extracted and amplified by polymerase chain reaction amplification of exons of the Norrie disease gene. The amplified products were sequenced by the dideoxy chain termination method.

RESULTS

The data revealed no disease-specific sequence alterations in the Norrie disease gene.

CONCLUSION

Although we cannot completely exclude the possibility of the Norrie disease gene as a candidate gene, the above results suggest that the structural and functional changes in the Norrie disease gene are not associated with clinically typical retinoschisis families that do not contain mutations in the coding regions and splice sites of the retinoschisis gene.

[Hereditary anterior megalophthalmus--a genealogical study of 12 patients in 4 generations]

BACKGROUND

The debate about whether megalophthalmus anterior is a diagnosis that needs to be distinguished clearly from buphthalmus or whether there are indeed connections between the two disorders is just as topical today as it was when the disorder was first described. With the aid of a genealogical examination, the symptoms of megalophthalmus anterior and the way in which they differ to those of buphthalmus will be shown.

PATIENTS AND METHODS

Twelve individuals making up an age span over four generations formed the genealogical tree. In seven of the family members, the subjective refraction, the javal, the applanation values and the diameter of the cornea, both vertically and horizontally, were established, along with the length of the axis of the eye and the depth of the anterior chamber partly measured biometrically. In addition, a detailed slitlamp examination of the anterior section was carried out, together with a gonioscopy and a funduscopy. On four of these who bore the symptoms, a 30-2 cental visual field test was carried out using the Humphrey apparatus and evaluated.

RESULTS

The megalophthalmus anterior which used to be known by the name megalocornea globosa Kaiser-Grönholm, involves not only a megalocornea with a vertical diameter of the cornea of between 12.5-14.5 mm, but also an enlargement of the whole anterior section of the eye with iridodonesis and lentodonesis. In addition, through the existing series of examinations, the following characteristics of megalophthalmus were found: symmetrical differences between each side, a global front of the coenea with partly thining in the central region, crocodile chagrin, no sign of glaucoma (normal intaocular pressure, a practically normal angle of the iris, no excavatio papillae, no loss in the field of vision) and recessive x-chromosomal heredity.

CONCLUSIONS

In order to eliminate buphthalmus and to diagnose megalophthalmus anterior, the difficulty in correctly analysing the results seems to lie in the lack of glaucoma, in the findings in the anterior section and in the conditions hereditary tendency.

Lisch corneal dystrophy is genetically distinct from Meesmann corneal dystrophy and maps to xp22.3

PURPOSE

There is an ongoing discussion whether Lisch corneal dystrophy (band-shaped and whorled microcystic dystrophy of the corneal epithelium) represents a disorder that is different from Meesmann corneal dystrophy. The purpose of this study was to evaluate at the molecular level if Lisch and Meesmann corneal dystrophies are genetically distinct.

METHODS

We examined at the slit lamp a total of 48 members of a family with an aggregation of Lisch corneal dystrophy. Genomic DNA was extracted from leukocytes of the peripheral blood of seven affected and six unaffected members of this family. Mutational hotspots in the cornea-specific keratin genes K3 and K12 were scanned for mutations by single-strand conformation analysis. To test for linkage to the keratin K3 or K12 loci or for X-chromosomal inheritance, six (K3) and four (K12) microsatellite markers each flanking the keratin loci as well as 22 microsatellite markers covering the X-chromosome were typed. Linkage was analyzed using the MLINK and FASTMAP procedures.

RESULTS

A total of 19 trait carriers were identified in six generations of the family. No hereditary transmission from father to son was observed. Linkage was excluded for the keratin K3 and K12 genes. Furthermore, single-strand conformation analysis detected no mutations in these genes. Multipoint linkage analysis revealed linkage with a maximum likelihood of the odds (LOD) score of 2.93 at Xp22.3. Linkage was excluded for Xp22.2 to Xqter.

CONCLUSIONS

Lisch corneal dystrophy is genetically different from Meesmann corneal dystrophy. Evidence was found for linkage of the gene for Lisch corneal dystrophy to Xp22.3.

Three loops of the common gamma chain ectodomain required for the binding of interleukin-2 and interleukin-7

The common gamma chain (gammac), a subunit of the interleukin (IL)-2, IL-4, IL-7, IL-9, and IL-15 receptors, contributes to both cytokine binding and subsequent signal transduction. Using a model-based site-directed mutagenesis strategy, we have identified residues of the mouse gammac extracellular domain that are required for normal gammac-dependent enhancement of IL-2 and IL-7 binding. One of these sites, Tyr-103, is homologous to key ligand-interacting residues in the growth hormone and erythropoietin receptors, whereas Cys-161, Cys-210, and Gly-211 may function indirectly by maintaining the functional conformation of gammac via formation of an intramolecular disulfide bond. These two cysteines are also required for the integrity of a putative epitope recognized by TUGm2, an antagonistic monoclonal antibody that blocks gammac-dependent cytokine binding and bioactivity. These results are consistent with the involvement of three predicted loops in gammac that contribute to the binding of both IL-2 and IL-7. Mutations in these loops have also been noted in the gammac gene of patients with X-linked severe combined immunodeficiency.

[Sex-linked mental retardation]

It has long been known that among patients with mental retardation males outnumber females. This is the result of mutations in X-chromosomal genes: X-linked mental retardation. Its prevalence has been estimated as 1.8/1000 males with a carrier frequency of 2.4/1000 females. X-linked mental retardation is divided into syndromic and non-specific types. At present there are about 135 syndromic forms known of 26 of which the responsible genes and mutations have been found. 8 genes are known in which mutations have been found in non-specific X-linked mental retardation. It is estimated that about 100 genes are involved in the latter. These genes are in particular involved in the function of the central nervous system. The development of a complete genetic map of the X-chromosome and the introduction of microarray techniques will in the short term enormously enhance the elucidation of X-linked mental retardation.

Prenatal diagnosis and genetic analysis of double trisomy 48,XXX,+18

Prenatal diagnosis of simultaneous occurrence of double trisomy involving chromosomes 18 and X is extremely rare. We report on the prenatal diagnosis, genetic analysis and clinical manifestations of a fetus with both trisomy 18 and trisomy X. A 26-year-old, para 1 woman was referred for genetic counselling at 36 weeks' gestation with the sonographic findings of intrauterine growth retardation (IUGR), polyhydramnios, ventricular septal defect, and an enlarged cisterna magna. Both cordocentesis and amniocentesis revealed a consistent karyotype of 48,XXX,+18. Quantitative fluorescent polymerase chain reaction using polymorphic small tandem repeat markers specific for chromosomes 18 and X rapidly determined that both aneuploidies arose as a result of non-disjunction in maternal meiosis II. Our case shows that two non-disjunction events can occur not only in the same parent, but also in the same cell division. Our case also shows that double trisomy, 48,XXX,+18, can demonstrate an enlarged cisterna magna, IUGR and polyhydramnios in prenatal ultrasound.

Parental and meiotic origin of triploidy in the embryonic and fetal periods

Triploidy is a common finding both in early spontaneous abortions and in the fetal period. Previous studies suggested that the majority of triploidy was the result of diandry, specifically dispermy. Molecular determination of parental origin in fetal triploids has shown that digyny accounts for the majority of triploids in the fetal period. The aim of this study was to determine the meiotic level at which the error leading to digynic triploidy occurs and to extend the molecular analysis of parental origin of triploidy into the embryonic period. Maternal age of digynic triploids was compared with that of the diandric cases. Using polymorphic pericentromeric markers, we have shown that the majority of digynic triploidy is the result of errors in the second meiotic division. Digyny accounted for the majority of triploids, even in the nonfetal cases. Diandry predominated in a subset of the non-fetal cases in which embryos were not present and in which the placental findings of partial hydatidiform mole (PHM) were encountered. Maternal age differed between the digynic and diandric groups only for the non-fetal cases; this was attributed to differences in ascertainment.

Drop episodes in Coffin-Lowry syndrome: an unusual type of startle response

We present a patient with a complete Coffin-Lowry syndrome, associated with drop episodes precipitated by sudden auditory stimuli, which provoked in turn, a definite loss of muscle tone in both legs. Electrophysiological studies showed that these episodes are an unusual type of startle response and that they may be associated with Coffin-Lowry syndrome.