Identification of the molecular defect in patients with peroxisomal mosaicism using a novel method involving culturing of cells at 40 degrees C: implications for other inborn errors of metabolism.

The peroxisome biogenesis disorders (PBDs), which comprise Zellweger syndrome (ZS), neonatal adrenoleukodystrophy, and infantile Refsum disease (IRD), represent a spectrum of disease severity, with ZS being the most severe, and IRD the least severe disorder. The PBDs are caused by mutations in one of the at least 12 different PEX genes encoding proteins involved in the biogenesis of peroxisomes. We report the biochemical characteristics and molecular basis of a subset of atypical PBD patients. These patients were characterized by abnormal peroxisomal plasma metabolites, but otherwise normal to very mildly abnormal peroxisomal parameters in cultured skin fibroblasts, including a mosaic catalase immunofluorescence pattern in fibroblasts. Since this latter feature made standard complementation analysis impossible, we developed a novel complementation technique in which fibroblasts were cultured at 40 degrees C, which exacerbates the defect in peroxisome biogenesis. Using this method, we were able to assign eight patients to complementation group 3 (CG3), followed by the identification of a single homozygous c.959C>T (p.S320F) mutation in their PEX12 gene. We also investigated various peroxisomal biochemical parameters in fibroblasts at 30 degrees C, 37 degrees C, and 40 degrees C, and found that all parameters showed a temperature-dependent behavior. The principle of culturing cells at elevated temperatures to exacerbate the defect in peroxisome biogenesis, and thereby preventing certain mutations from being missed, may well have a much wider applicability for a range of different inborn errors of metabolism.

Clinical, cytogenetic, and molecular findings of prenatally diagnosed mosaic trisomy 4.

OBJECTIVES: To present the clinical, cytogenetic, and molecular findings of prenatally diagnosed mosaic trisomy 4. CASE: An amniocentesis was performed at 21 weeks' gestation because of maternal anxiety. Cytogenetic analysis revealed mosaicism for trisomy 4, 47,XX,+4[4]/46,XX[16]. Level II ultrasound demonstrated tetralogy of Fallot. Repeated amniocentesis at 23 weeks' gestation revealed 47,XX,+4[4]/46,XX[19]. The pregnancy was terminated. Phenotypic findings included tetralogy of Fallot, hypertelorism, micrognathia, abnormal ears, duplicated phalanges of the left thumb, clinodactyly, and overlapping of the toes. The karyotype of the cord blood was 46,XX. Cytogenetic analyses of the multiple tissue samplings showed a karyotype of 47,XX,+4 in 40/40 cells of the amniotic membrane (amnion), and 47,XX,+4/46,XX with various levels of trisomy 4 in the cells of the liver, lungs, placenta, skin, and umbilical cord. The levels of trisomy 4 were 11/40 in the liver, 8/40 in the lungs, 31/40 in the placenta, 9/40 in the skin, and 8/40 in the umbilical cord. METHOD: The parental origin and meiotic origin of trisomy 4 were determined by examining the amniotic membrane using quantitative fluorescent polymerase chain reaction assays with polymorphic markers specific for chromosome 4. The result was consistent with a paternal meiosis I nondisjunction error. The cord blood showed a biparental inheritance. An extra paternal heterozygous allele with partial dosage increase was noted in other fetal and extraembryonic tissues studied. CONCLUSION: A diagnosis of trisomy 4 mosaicism in amniocytes indicates an increased risk for fetal abnormalities. Associated abnormal findings include congenital heart defects and anomalies of the digits and thumb. A confirmatory placental sampling may be helpful, whereas a fetal blood sampling is of a very limited value. A postnatal amnion sampling may provide additional clues to the fetal involvement of trisomy 4.

Two cases of tetrasomy 9p syndrome with tissue limited mosaicism.

Tetrasomy of short arm of chromosome 9 constitutes a clinically recognizable chromosomal syndrome. Isochromosome 9p shows a strong propensity to tissue-limited mosaicism. It occurs predominantly in peripheral blood cultures, often at a lower frequency or even absent in skin, amniotic fluid or chorionic villous cell cultures. Tissue-limited nature of mosaicism may render prenatal detection of this condition very difficult. Herein, we report two new cases of mosaic tetrasomy 9p. Conventional cytogenetics (CC) and FISH studies demonstrated a differential expression of the mosaicism in several tissues. We review the literature and discuss the implications of these findings in cytogenetic prenatal diagnosis.

Improved accuracy of hysteroembryoscopic biopsies for karyotyping early missed abortions.

OBJECTIVE: To assess the potential of direct embryo and chorion biopsies obtained by hysteroembryoscopy for karyotyping early missed abortions. DESIGN: Clinical prospective descriptive study. SETTING: Instituto Valenciano de Infertilidad, Valencia, Spain. PATIENT(S): Sixty-eight women (71 gestational sacs) with missed abortions. The gestational age on ultrasound was 6.3 weeks (range, 4-10 weeks). INTERVENTION(S): Transcervical hysteroembryoscopy before curettage. MAIN OUTCOME MEASURE(S): Comparison between the cytogenetic results from hysteroembryoscopic biospies and those of the curettage material. RESULT(S): Hysteroembryoscopic biopsies could be taken in 97.2% of the gestational sacs. Direct embryo and chorion biopsies were suitable for chromosomal analysis. Selective samples identified misdiagnoses of the conventional curettage karyotype due to maternal contaminating tissues in 22.2% of the cases. Direct hysteroembryoscopic biopsies also enabled the diagnosis of a true placental mosaicism and the study of the individual karyotype of each gestational sac in bizygotic twin missed abortions. CONCLUSION(S): In early missed abortions, karyotypes from direct hysteroembryoscopic biopsies were more accurate than those from the curettage material. The finding of a 46,XX karyotype in the curettage material is not a reliable result.

Linear atrophoderma of Moulin: postulation of mosaicism for a predisposing gene.

Hyperpigmented atrophoderma arranged in a pattern following the lines of Blaschko and appearing during childhood or adolescence on the trunk or the limbs is a characteristic feature of linear atrophoderma of Moulin. We review 15 published reports and describe 4 additional cases. Histopathologically, there is no clear sign of atrophy found in specimens examined by light microscopy. It might well be argued that a focal reduction of subcutaneous fatty tissue contributes to the obvious clinical atrophy. The cause and pathogenesis of the disorder remains unknown. It may reflect mosaicism caused by a postzygotic mutation that occurred at an early developmental stage, in analogy to many other diseases distributed along Blaschko's lines. Linear atrophoderma of Moulin may reflect the action of an autosomal lethal gene surviving by mosaicism. There are so far no reports of a familial occurrence that could favor a paradominant transmission of linear atrophoderma of Moulin. However, theoretically, the postzygotic mutation giving rise to an aberrant cell clone could still be nonlethal. In a heterozygous individual, a postzygotic mutational event might lead to loss of the corresponding wild-type allele at the atrophoderma locus. This would give rise to a homozygous cell clone, which becomes manifest along the lines of Blaschko later in life.

Association of Turner's syndrome and hypopituitarism: a patient report.

Turner's syndrome (TS) is associated with a wide spectrum of clinical features, such as short stature and gonadal dysgenesis. While it is a common chromosomal abnormality, the association of Turner's syndrome and hypopituitarism is an uncommon finding. We describe here a girl with concomitant pituitary insufficiency and gonadal dysgenesis. When she was 7 years old, her mother reported that she suffered from frontal headache, asthenia and delayed growth. Basal laboratory thyroid evaluation suggested hypothyroidism, with no evidence of autoimmune disease association. She began taking L-thyroxine. At age 11 years, short stature and complaints of frontal headache still persisted. She was still prepubertal and her bone age was delayed by 2.2 years. Her karyotype was compatible with 45,X/46,XX (100 cells analyzed by FISH) and a CT scan showed empty sella. At 12 years of age, an anterior pituitary stimulation test with insulin, gonadotropin-releasing hormone (GnRH) and thyrotropin-releasing hormone (TRH) showed gonadotropin, thyrotropin (TSH) and growth hormone (GH) deficiency. Replacement therapy with GH was begun and she grew 12 cm during the first year of treatment. This report illustrates that, despite the high incidence of sinusitis, short stature and primary hypothyroidism in TS, we should consider the presence of hypopituitarism when the patient presents low levels of TSH with negative thyroid antibodies and inappropriately low levels of gonadotropins for patients with gonadal dysgenesis.

Turner's syndrome in fetal life.

OBJECTIVE: To compare the incidence and type of heart disease found in association with 45X karyotype in fetal life with postnatal life and to examine the outcome after fetal diagnosis. METHODS: Fifty-three fetuses with a 45X karyotype were examined echocardiographically over a 4-year period between 1999 and 2002. Of these, 47 were referred because of increased nuchal translucency (NT). RESULTS: A cardiac abnormality was detected in 33/53 (62.2%) fetuses. The most common diagnosis was coarctation of the aorta in 24/53 (45.3%) fetuses, followed by the hypoplastic left heart syndrome (HLHS) in 7/53 (13.2%) fetuses. The mean NT was significantly higher in fetuses with a heart defect than in those with normal echocardiography. Termination of pregnancy was carried out in 45/53 (84.9%) fetuses and intrauterine death occurred in six cases. Two of four fetuses with a mosaic karyotype are currently alive. CONCLUSION: Turner's syndrome is associated with a higher incidence of heart defects detected prenatally when compared to postnatal reports. The commonest associated heart defects detected prenatally are HLHS and coarctation of the aorta, in contrast to postnatal life where a bicuspid aortic valve is the most common diagnosis. The typical intrauterine presentation of Turner's syndrome with a markedly increased NT or with hydrops and with a typical 45X karyotype has an extremely poor prognosis for intrauterine survival.

Pallister-Mosaic syndrome and neuronal migration disorder.

We diagnosed Pallister-Mosaic syndrome (PMS) in a 4-month-old female infant. In addition to the presence of non-specific anomalies, involving anorectal, finger and ear anomalies, characteristic cranio-facial features and irregular skin lesions that appeared after age 2 months suggested the possibility of genetic mosaicism, PMS in particular. Fluorescence in situ hybridization technique revealed an extra copy of chromosome 12p; i (12p) in 30% of cultured skin fibroblasts. When focal skin lesions accompany neurodevelopmental disabilities in early infancy, genetic analysis for mosaicism should be considered for differential diagnosis. Significantly, we describe several phenotypic features and neuroimaging findings of the PMS in the present case, which have not been described in previous reports. The neuroimaging abnormalities we encountered, such as polymicrogyria, speculating congenital brain anomaly, may explain the severe motor and intellectual disabilities of PMS.

Bilateral frontal polymicrogyria and epilepsy in a patient with Turner mosaicism: a case report.

Turner's syndrome (TS) is rarely associated with serious abnormalities of brain structure or malformations of cortical development. We report a 17-year-old girl with TS and 45,XO/46,XX mosaicism presenting bilateral frontal polymicrogyria (BFP) and epilepsy. To our knowledge, the association between TS and BFP has never been reported to date. Our observation confirms that in humans the X-chromosome plays an important role in the development and specialization of brain structure and function. We hypothesize that the absence or abnormalities of developmental genes localized on the X-chromosome could be involved in the pathogenesis of BFP observed in our patient.

Anaesthetic management of a child with Pallister-Killian syndrome.

Pallister-Killian syndrome is characterized by tetrasomy of the short arm of chromosome 12p, which produces mental retardation of varying degrees and dysmorphic characteristics. We describe anaesthesia in a 2-year-old child affected by this syndrome who underwent surgery for orchidopexy. Anaesthetic consisted of an inhalation mixture of O2, N2O and sevoflurane, together with an inguinal block with ropivacaine and administration of alfentanil plus ketorolac. Tracheal intubation was uneventful. No complications of any type were observed.

[Mosaicism of the upper respiratory tract epithelium in liquidators of the Chernobyl accident]. / Mozaichnost' épiteliia verkhnikh dykhatel'nykh putei u likvidatorov posledstvii avarii na ChAES.

On the basis of findings from the structural analysis of 21 nasal mucosa biopsy specimens of patients with chronic rhinitis including 12 participants in liquidation of the consequences of the Chernobyl accident using morphometric methods, signs of morphofunctional insufficiency of the nasal epithelium are verified. Mechanisms of this phenomenon development are discussed.

Brachmann-de Lange syndrome (BDLS) with asymmetry and skin pigmentary anomalies: a result of mosaicism for a putative bdls gene mutation?

Brachmann-de Lange syndrome (BDLS, OMIM 122470) is a rare malformation syndrome characterized by mental retardation, short stature, limb abnormalities, and a distinctive craniofacial appearance. There is wide clinical variability and mildly affected patients are common. The genetic basis of BDLS and the reasons for its phenotypical variability are still unknown. We report on a patient with mild BDLS and the unusual findings of asymmetric growth of one body half and irregularly shaped pigmentary anomalies of the skin. These two traits have not been previously described in BDLS but have been associated with phenomena of genetic mosaicism in other conditions. We suggest that this patient's phenotype could be the result of mosaicism for a mutation or submicroscopic deletion affecting one or several genes responsible for BDLS.

Acantholytic dyskeratotic naevi following Blaschko's lines: a mosaic form of Darier's disease.

Darier's disease (DD) is an autosomal-dominant skin disorder characterized by loss of adhesion between epidermal cells and abnormal keratinization. Several patients with unilateral, linear, 'zosteriform' or localized lesions have been reported. We report three cases of DD in a localized pattern corresponding to mosaicism type 1 according to Happle's classification and review the literature about the genetic cause of DD and DD in a 'zosteriform' pattern.

Prenatal diagnosis of double autosomal mosaicism (47,XX,+8/47,XX,+14): phenotype and molecular cytogenetic analysis on different tissues.

A female fetus with multiple congenital anomalies was found to have double autosomal mosaicism, 47,XX,+8/ 47,XX,+14 on chromosome analysis via amniocentesis. At delivery, the proband displayed dysmorphic features of hypertelorism, micrognathia, low set ears, cleft palate, clubfeet, omphalocele, absent gallbladder and congenital heart defects. Fluorescence in situ hybridization demonstrated a marked discrepancy in cell line populations in the tissues examined.

Apparently new autosomal dominant Spondyloepimetaphyseal dysplasia: gonadal mosaicism onset.

We report a family in which an apparently previously undescribed form of Spondyloepimetaphyseal dysplasia (SEMD) presented after probable gonadal mosaicism occurred and is inherited in an autosomal dominant mode. The other autosomal dominant SEMDs are compared.

Intranuclear inclusions, neuronal loss and CAG mosaicism in two patients with Machado-Joseph disease.

UNLABELLED: The presence of neuronal intranuclear inclusions (NIIs) and neuronal mosaicism has been described in some autosomal dominant spinocerebellar ataxias (SCA), but their implication in neurodegenerative mechanisms still remains unclear. OBJECTIVE: To investigate the correlation between neuronal loss and NIIs, and the size of CAG triplet expansion in selected areas of the CNS in two SCA3 patients. MATERIAL AND METHODS: Postmortem neuropathological study was carried out, and the regional distribution of neuronal loss was compared with NIIs. CAG expansion was analysed by PCR amplification in the same regions. RESULTS: Marked neuronal loss was seen in the anterior horn of the spinal cord, pontine nuclei and motor nuclei of the brain stem. Moderate neurone loss was found in the locus ceruleus, colliculus and substantia nigra. Loss of granule and Purkinje cells was found in the cerebellum, mainly in the vermis. NIIs were present in neurones of the involved nuclei of the anterior horn of the spinal cord, medulla oblongata and pons, but not in the locus ceruleus, substantia nigra and cerebellum. A few NIIs were found in the striatum. The number of CAG repeats was 27/70 in the first patient and 21/74 in the second patient. The variation of the expanded allele size among different cerebral areas was +/-1-3 CAG repeats. CONCLUSION: The partial correlation between neuronal loss and NIIs suggests that other factors distinct from NII formation may be involved in the neuronal death. Moreover, the low degree of mosaicism between regions without neuronal loss and regions with marked neuronal loss points to the existence of selective cellular vulnerability to the genetic defect.

Partial revertant mosaicism of keratin 14 in a patient with recessive epidermolysis bullosa simplex.

A patient with recessive epidermolysis bullosa simplex due to a previously described homozygous KRT14 1842-2A-->C splice-site mutation was re-examined, because we unexpectedly found signs of revertant mosaicism. The germline mutation resulted in different aberrant transcripts containing premature termination codons, all leading to truncated keratin 14 proteins. Basal keratinocytes in skin and in culture completely lacked keratin 14 and intermediate filaments. From this keratin 14-/- patient we started cultures from a new skin biopsy and here, we serendipitously found keratinocytes that spontaneously expressed keratin 14. This biopsy had been taken from an area of skin that was clinically affected, because blisters could simply be evoked by gentle rubbing. Immunofluorescence and electron microscopy of additional biopsies from this skin area revealed a mosaic expression of keratin 14 and reappearance of intermediate filaments in basal keratinocytes. Immunoblotting showed a revertant keratin 14 polypeptide with seemingly normal molecular weight. DNA analysis of exon 2 and its flanking intron borders showed no additional mutations in the genomic KRT14 sequence. Analysis of mRNA isolated from mosaic skin keratinocytes revealed an additional in-frame transcript (1844T-->G, 1845Delta6) that codes for an abnormal keratin 14 polypeptide with a two residue deletion and one amino acid change. The re-expression of a revertant, albeit abnormal, keratin 14 polypeptide, so-called partial revertant mosaicism, accounts for the antibody staining pattern and for the reappearance of intermediate filaments, which however, are semifunctional and not able to revert the clinical phenotype. The combination of a keratin 14-positive and a keratin 14-negative cell population in epidermis as well as in cultured keratinocytes suggests that the cellular reversion might be caused by an endogenous factor. We hypothesize that a second somatic modulating factor in the genome that affects the processing of the mutant KRT14 pre-mRNA may underlie this phenomenon.

Pathological structure of the kidney from adult mice with mosaic mutation.

The mosaic (Atp7a(mo-ms)) is an X-linked, lethal mutation in mice. In mosaic mutant males, many clinical features characteristic of defective copper metabolism have been observed and they die at the age of 15 days, exhibiting strong similarities to the brindled and macular mutants. About 4% of the mutant males live to sexual maturity and some of them are fertile. In this paper, alterations in the structure of the kidney from adult mutants are described. Owing to an inherited defect of efflux, copper is accumulated in the kidney of the mutants up to a toxic level and this leads to severe damage of the renal cortex. Pathological changes in the kidney mostly affected the structure of the renal corpuscle and renal tubules.