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PubMed2003

A splicing mutation affecting expression of ataxia-telangiectasia and Rad3-related protein (ATR) results in Seckel syndrome.

Seckel syndrome (OMIM 210600) is an autosomal recessive disorder characterized by intrauterine growth retardation, dwarfism, microcephaly and mental retardation. Clinically, Seckel syndrome shares features in common with disorders involving impaired DNA-damage responses, such as Nijmegen breakage syndrome (OMIM 251260) and LIG4 syndrome (OMIM 606593). We previously mapped a locus associated with Seckel syndrome to chromosome 3q22.1-q24 in two consanguineous Pakistani families. Further marker analysis in the families, including a recently born unaffected child with a recombination in the critical region, narrowed the region to an interval of 5 Mbp between markers D3S1316 and D3S1557 (145.29 Mbp and 150.37 Mbp). The gene encoding ataxia-telangiectasia and Rad3-related protein (ATR) maps to this region. A fibroblast cell line derived from an affected individual displays a defective DNA damage response caused by impaired ATR function. We identified a synonymous mutation in affected individuals that alters ATR splicing. The mutation confers a phenotype including marked microcephaly (head circumference 12 s.d. below the mean) and dwarfism (5 s.d. below the mean). Our analysis shows that UV-induced ATR activation can occur in non-replicating cells following processing by nucleotide excision repair.

Ataxia Telangiectasia Mutated Proteins↗

PubMed2003

Mutations in ARFGEF2 implicate vesicle trafficking in neural progenitor proliferation and migration in the human cerebral cortex.

Disruption of human neural precursor proliferation can give rise to a small brain (microcephaly), and failure of neurons to migrate properly can lead to an abnormal arrest of cerebral cortical neurons in proliferative zones near the lateral ventricles (periventricular heterotopia). Here we show that an autosomal recessive condition characterized by microcephaly and periventricular heterotopia maps to chromosome 20 and is caused by mutations in the gene ADP-ribosylation factor guanine nucleotide-exchange factor-2 (ARFGEF2). By northern-blot analysis, we found that mouse Arfgef2 mRNA levels are highest during embryonic periods of ongoing neuronal proliferation and migration, and by in situ hybridization, we found that the mRNA is widely distributed throughout the embryonic central nervous system (CNS). ARFGEF2 encodes the large (>200 kDa) brefeldin A (BFA)-inhibited GEF2 protein (BIG2), which is required for vesicle and membrane trafficking from the trans-Golgi network (TGN). Inhibition of BIG2 by BFA, or by a dominant negative ARFGEF2 cDNA, decreases cell proliferation in vitro, suggesting a cell-autonomous regulation of neural expansion. Inhibition of BIG2 also disturbed the intracellular localization of such molecules as E-cadherin and beta-catenin by preventing their transport from the Golgi apparatus to the cell surface. Our findings show that vesicle trafficking is an important regulator of proliferation and migration during human cerebral cortical development.

ADP-Ribosylation Factors↗

PubMed2005

An essential function for NBS1 in the prevention of ataxia and cerebellar defects.

Nijmegen breakage syndrome (NBS), ataxia telangiectasia and ataxia telangiectasia-like disorder (ATLD) show overlapping phenotypes such as growth retardation, microcephaly, cerebellar developmental defects and ataxia. However, the molecular pathogenesis of these neurological defects remains elusive. Here we show that inactivation of the Nbn gene (also known as Nbs1) in mouse neural tissues results in a combination of the neurological anomalies characteristic of NBS, ataxia telangiectasia and ATLD, including microcephaly, growth retardation, cerebellar defects and ataxia. Loss of Nbn causes proliferation arrest of granule cell progenitors and apoptosis of postmitotic neurons in the cerebellum. Furthermore, Nbn-deficient neuroprogenitors show proliferation defects (but not increased apoptosis) and contain more chromosomal breaks, which are accompanied by ataxia telangiectasia mutated protein (ATM)-mediated p53 activation. Notably, depletion of p53 substantially rescues the neurological defects of Nbn mutant mice. This study gives insight into the physiological function of NBS1 (the Nbn gene product) and the function of the DNA damage response in the neurological anomalies of NBS, ataxia telangiectasia and ATLD.

ATP-Binding Cassette Transporters↗

PubMed2006

Exonic microdeletions in the X-linked PQBP1 gene in mentally retarded patients: a pathogenic mutation and in-frame deletions of uncertain effect.

Mutations in PQBP1 were recently identified in families with syndromic and non-syndromic X-linked mental retardation (XLMR). Clinical features frequently associated with MR were microcephaly and/or short stature. The predominant mutations detected so far affect a stretch of six AG dinucleotides in the polar-amino-acid-rich domain (PRD), causing frameshifts in the fourth coding exon. We searched for PQBP1 exon 4 frameshifts in 57 mentally retarded males in whom initial referral description indicated at least one of the following criteria: microcephaly, short stature, spastic paraplegia or family history compatible with XLMR, and in 772 mentally retarded males not selected for specific clinical features or family history. We identified a novel frameshift mutation (23 bp deletion) in two half-brothers with specific clinical features, and performed prenatal diagnosis in this family. We also found two different 21 bp in-frame deletions (c.334-354del(21 bp) and c.393-413del(21 bp)) in four unrelated probands from various ethnic origins, each deleting one of five copies of an imperfect seven amino-acid repeat. Although such deletions have not been detected in 1180 X chromosomes from European controls, the c. 334-354del(21 bp) was subsequently found in two of 477 Xs from Indian controls. We conclude that pathogenic frameshift mutations in PQBP1 are rare in mentally retarded patients lacking specific associated signs and that the 21 bp in-frame deletions may be non-pathogenic, or alternatively could act subtly on PQBP1 function. This touches upon a common dilemma in XLMR, that is, how to distinguish between mutations and variants that may be non-pathogenic or represent risk factors for cognitive impairment.

Adolescent↗

PubMed2001

Brain damage after neonatal tetanus in a rural Kenyan hospital.

OBJECTIVE: Neonatal tetanus (NNT) is an important cause of mortality in resource poor countries, particularly sub-Saharan Africa. There are no reports of the long-term outcome of children who survive NNT in African hospitals. DESIGN: In a retrospective study of children discharged from Kilifi District Hospital (KDH), Kenya with NNT, each child was linked with a comparative child (CC) in the community matched for age, sex and locality. PARTICIPANTS: A total of 123 patients were admitted with NNT between 1992 and 1996, of whom 68% died. Twenty-three (59%) of the 39 survivors were traced in the community, 10 had moved away, six had died. OUTCOME MEASURES: NNT survivors underwent a neurological and developmental examination and a questionnaire was administered to the parents about the behaviour of the child. A verbal autopsy was used to determine the cause of death in children who had died after discharge. RESULTS: The head circumference of NNT survivors was significantly smaller than that of CC (P=0.037); eight children had microcephaly compared with one CC (P=0.011). NNT survivors had more problems with hand-eye co-ordination tasks (P=0.035), a lower summated developmental score (P=0.023) and more mild neurological abnormalities (P=0.008) than CC. Parents of NNT survivors reported more behavioural problems (P=0.02) than parents of CC. CONCLUSIONS: Children who survive NNT have evidence of brain damage that manifests as microcephaly, mild neurological abnormalities, developmental impairment - particularly fine motor difficulties - and behaviour problems.

Brain Damage, Chronic↗

PubMed2004

Outcome at 5 years of age of SGA and AGA infants born less than 28 weeks of gestation.

The objective of this study was to compare the outcomes at 5 years of age of SGA and AGA children born < 28 weeks of gestation. The method used was a longitudinal follow-up of a cohort of 37 dyads of SGA and AGA infants matched by gestational age (GA), gender, and date of delivery. Mean GA was 26+/-1.2 weeks, and BW was 638+/-77 g for SGA and 833+/-134 g for AGA (P < 0.0001). The SGA infants remained lighter at 3, 24, and 60 months. Their head circumference was statistically smaller at 3 and 60 months, and their length remained lower but no longer statistically significant. There was no difference after the second year of life between SGA and AGA children in the need for rehospitalization (16% versus 11%) and the incidence of medical problems such as Otitis (38% versus 41%) and asthma (24% versus 30%). SGA exhibited more neurodevelopmental deficits (41% versus 30%) and severe handicaps, including CP, blindness, deafness, and mental retardation (22% versus 14%). Those deficits were seen predominantly in association with microcephaly, which was more prevalent in the SGA group. We conclude that the combination of severe prematurity and intrauterine growth retardation constitutes a serious developmental handicap and predisposes to physical and developmental delays. The presence of microcephaly further aggravates the prognosis.

Anthropometry↗

PubMedDate not supplied

[Intrauterine herpes simplex virus infection].

BACKGROUND: Early fetal herpes simplex virus (HSV) infection is rarely documented. Only the minority of affected fetuses survive this condition. PATIENT AND METHODS: At 19 weeks of gestation the first episode of a genital HSV-infection of a pregnant woman was treated with local interferon beta. At 34 weeks of gestation hydrocephalus with secondary microcephaly and microphthalmia of both eyes was detected by ultrasonography. In the amniotic fluid HSV type 2 (HSV-2) was isolated and HSV-2-DNA was detected by PCR. The serum of the mother proved positive for HSV-2 (glycoprotein G2)-specific IgG-antibodies. No other infectious causes were apparent on further testing. At 35 + 4 weeks gestation a small-for-gestational-age neonate (2130 g) with microcephaly (29 cm head circumference) was born by spontaneous vaginal delivery. Scarce ulcerative skin lesions and vesicles, hepatosplenomegaly and microphthalmia were diagnosed. Furthermore, encephalomalacia with parenchymal destruction, cataract of both eyes and aplasia of the maculae and papillae were found. HSV-2-PCR was tested positive in chorionic cells and an umbilical segment of the placenta as well as in swabs from both eyes, throat, and a herpetic skin lesion collected during the first 5 days of life. HSV-IgM-antibodies were found in the umbilical cord blood. Local and intravenous treatment with aciclovir was started. The infant exhibited signs of a severely malfunctioning central nervous system. At the age of 4 months the boy suffered from generalised cerebral seizures. He died at the age of 9 months as a consequence of respiratory insufficiency with consecutive circulation failure. RESULTS: The case of an intrauterine HSV-2-infection is presented. The time of onset of fetal infection was most probably at the time of the maternal disease (19 weeks of gestation). Inspite of the very early infection the fetus did not die in utero. CONCLUSIONS: Especially, if a primary genital HSV-2-infection of a pregnant woman is suspected, which can be proven by serological means only several weeks after infection, systemic therapy of the mother with aciclovir should be considered since materno-fetal transmission may occur due to the risk of maternal viraemia.

Abnormalities, Multiple↗

PubMed1989

Encephalopathy with calcifications of the basal ganglia in children. A reappraisal of Fahr's syndrome with respect to 14 new cases.

Calcifications of the basal ganglia are described under the heading of "Fahr's syndrome". The clinical pattern is variable and the syndrome may be sporadic or familial. This study describes a personal series of 14 cases of encephalopathy with calcification of the basal ganglia and reviews the literature cases. A four-group classification is proposed. The first group includes encephalopathy, microcephaly, dwarfism, retinal degeneration or optic atrophy, symmetrical patchy demyelination with calcifications and probable autosomal recessive inheritance. Some cases have an early onset, a rapid evolution. Others have a later onset, longer course and retinal degeneration. In the second group, the children suffer from a congenital encephalopathy or a cerebral palsy without clear deterioration, without short stature, ocular impairment or persistent CSF abnormalities. This group has not been reported in the literature. The cases do not seem to be genetic. The precise cause in unknown but a sporadic non progressive anoxo-ischemic, or viral prenatal disease is suggested. In the third group, the association of encephalopathy, microcephaly, and persistent CSF lymphocytosis, has a high recurrence rate. The pathogenesis is still a matter of dispute. The fourth group is characterized by autosomal dominant calcifications of the basal ganglia with or without neurological abnormalities. Finally calcium metabolism disorders and mitochondrial encephalomyopathy may be associated with calcifications of the basal ganglia.

Basal Ganglia Diseases↗

PubMed2000

Etiologic yield of subspecialists' evaluation of young children with global developmental delay.

OBJECTIVE: To determine the etiologic yield of subspecialists' evaluation of young children with global developmental delay. In addition, variables that may predict finding an underlying etiology were also identified. METHODS: All children <5 years of age, referred over an 18-month period to subspecialty services for initial evaluation of a suspected developmental delay, were prospectively enrolled. Diagnostic yield was ascertained after the completion of clinical assessments and laboratory investigations requested by the evaluating physician. RESULTS: Ninety-nine children (71 boys) were found to have global developmental delay; 96% had a mild or moderate delay documented. An etiologic diagnosis was determined in 44. Four diagnoses (cerebral dysgenesis, hypoxic-ischemic encephalopathy, toxin exposure, chromosomal abnormalities) accounted for 34 of 44 (77%) of the diagnoses made. The presence of co-existing autistic traits was associated with significantly decreased diagnostic yield (0/19 vs 44/80, P <.0001), whereas specific historical features (eg, family history, toxin exposure, and perinatal difficulty; 23/32 vs 21/67, P =.0002) and findings on physical examination (eg, dysmorphology, microcephaly, and focal motor findings; 35/48 vs 9/51, P <.0001) were significantly associated with identifying a diagnosis. Multiple logistic regression analysis identified antenatal toxin exposure, microcephaly, focal motor findings, and the absence of autistic traits as significant predictor variables for the identification of an etiology. CONCLUSION: An etiologic diagnosis is often possible in the young child with global developmental delay, particularly in the absence of autistic features. Etiologic yield is augmented by presence of specific findings on history or physical examination on initial assessment.

Autistic Disorder↗

PubMed2006

Aspm specifically maintains symmetric proliferative divisions of neuroepithelial cells.

The ASPM (abnormal spindle-like microcephaly-associated) protein has previously been implicated in the determination of human cerebral cortical size, but the cell biological basis of this regulation has not been studied. Here we investigate the role of Aspm in mouse embryonic neuroepithelial (NE) cells, the primary stem and progenitor cells of the mammalian brain. Aspm was found to be concentrated at mitotic spindle poles of NE cells and to be down-regulated with their switch from proliferative to neurogenic divisions. Upon RNA interference in telencephalic NE cells, Aspm mRNA is reduced, mitotic spindle poles lack Aspm protein, and the cleavage plane of NE cells is less frequently oriented perpendicular to the ventricular surface of the neuroepithelium. The alteration in the cleavage plane orientation of NE cells increases the probability that these highly polarized cells undergo asymmetric division, i.e., that apical plasma membrane is inherited by only one of the daughter cells. Concomitant with the resulting increase in abventricular cells in the ventricular zone, a larger proportion of NE cell progeny is found in the neuronal layer, implying a reduction in the number of NE progenitor cells upon Aspm knock-down relative to control. Our results demonstrate that Aspm is crucial for maintaining a cleavage plane orientation that allows symmetric, proliferative divisions of NE cells during brain development. These data provide a cell biological explanation of the primary microcephaly observed in humans with mutations in ASPM, which also has implications for the evolution of mammalian brains.

Animals↗

PubMed2006

Pygmoid Australomelanesian Homo sapiens skeletal remains from Liang Bua, Flores: population affinities and pathological abnormalities.

Liang Bua 1 (LB1) exhibits marked craniofacial and postcranial asymmetries and other indicators of abnormal growth and development. Anomalies aside, 140 cranial features place LB1 within modern human ranges of variation, resembling Australomelanesian populations. Mandibular and dental features of LB1 and LB6/1 either show no substantial deviation from modern Homo sapiens or share features (receding chins and rotated premolars) with Rampasasa pygmies now living near Liang Bua Cave. We propose that LB1 is drawn from an earlier pygmy H. sapiens population but individually shows signs of a developmental abnormality, including microcephaly. Additional mandibular and postcranial remains from the site share small body size but not microcephaly.

Bicuspid↗

PubMed1999

Delineation of the critical deletion region for congenital heart defects, on chromosome 8p23.1.

Deletions in the distal region of chromosome 8p (del8p) are associated with congenital heart malformations. Other major manifestations include microcephaly, intrauterine growth retardation, mental retardation, and a characteristic hyperactive, impulsive behavior. We studied genotype-phenotype correlations in nine unrelated patients with a de novo del8p, by using the combination of classic cytogenetics, FISH, and the analysis of polymorphic DNA markers. With the exception of one large terminal deletion, all deletions were interstitial. In five patients, a commonly deleted region of approximately 6 Mb was present, with breakpoints clustering in the same regions. One patient without a heart defect or microcephaly but with mild mental retardation and characteristic behavior had a smaller deletion within this commonly deleted region. Two patients without a heart defect had a more proximal interstitial deletion that did not overlap with the commonly deleted region. Taken together, these data allowed us to define the critical deletion regions for the major features of a del8p.

Abnormalities, Multiple↗

PubMed2006

A novel domain suggests a ciliary function for ASPM, a brain size determining gene.

The N-terminal domain of abnormal spindle-like microcephaly-associated protein (ASPM) is identified as a member of a novel family of ASH (ASPM, SPD-2, Hydin) domains. These domains are present in proteins associated with cilia, flagella, the centrosome and the Golgi complex, and in Hydin and OCRL whose deficiencies are associated with hydrocephalus and Lowe oculocerebrorenal syndrome, respectively. Genes encoding ASH domains thus represent good candidates for primary ciliary dyskinesias. ASPM has been proposed to function in neurogenesis and to be a major determinant of cerebral cortical size in humans. Support for this hypothesis stems from associations between mutations in ASPM and primary microcephaly, and from the rapid evolution of ASPM during recent hominid evolution. The identification of the ASH domain family instead indicates possible roles for ASPM in sperm flagellar or in ependymal cells' cilia. ASPM's rapid evolution may thus reflect selective pressures on ciliary function, rather than pressures on mitosis during neurogenesis.

Amino Acid Sequence↗

PubMed2003

Evolution of the human ASPM gene, a major determinant of brain size.

The size of human brain tripled over a period of approximately 2 million years (MY) that ended 0.2-0.4 MY ago. This evolutionary expansion is believed to be important to the emergence of human language and other high-order cognitive functions, yet its genetic basis remains unknown. An evolutionary analysis of genes controlling brain development may shed light on it. ASPM (abnormal spindle-like microcephaly associated) is one of such genes, as nonsense mutations lead to primary microcephaly, a human disease characterized by a 70% reduction in brain size. Here I provide evidence suggesting that human ASPM went through an episode of accelerated sequence evolution by positive Darwinian selection after the split of humans and chimpanzees but before the separation of modern non-Africans from Africans. Because positive selection acts on a gene only when the gene function is altered and the organismal fitness is increased, my results suggest that adaptive functional modifications occurred in human ASPM and that it may be a major genetic component underlying the evolution of the human brain.

Anthropometry↗

PubMed1992

Symptomatic congenital cytomegalovirus infection: neonatal morbidity and mortality.

Knowledge of the natural history of symptomatic congenital cytomegalovirus (CMV) infection in the newborn is essential in order to anticipate complications and assess the potential benefit from antiviral therapy. To define the disease course we reviewed data on 106 neonates with symptomatic congenital CMV infection diagnosed and managed by the investigators. Petechiae, jaundice and hepatosplenomegaly were each noted in 70% or more patients. Microcephaly was noted in 54 of 102 (53%) at birth. Elevated alanine aminotransferase, conjugated hyperbilirubinemia and thrombocytopenia were seen in 83, 81 and 77%, respectively. Eighty-six percent had at least two of the manifestations highly suggestive of congenital infection. Platelet count fell to its nadir during the second week of life whereas elevated alanine aminotransferase and direct bilirubin persisted past the first month. In spite of the difficulty in assessing central nervous system function in the newborn, evidence of damage was present in the majority. Seventy-two had microcephaly, poor suck, lethargy/hypotonia or seizures. Abnormal computerized tomographic scan was present in 16 of 20 (80%) and decreased hearing in 20 of 39 (56%). Cerebrospinal fluid protein was greater than 120 mg/dl in 24 of 52 (46%) and this elevation was associated with neurologic abnormalities as well as hearing loss. The mean length of hospital stay was 13 and 22.4 days for term and preterm infants, relatively. Thirteen infants (12%) died during the first 6 weeks of life. Disseminated CMV infection with multiorgan involvement was evident in 7 of 9 at postmortem examination. We conclude that neonates with symptomatic congenital CMV infection have a multi-system disease with significant morbidity and mortality.

Cytomegalovirus Infections↗

PubMed1982

Dorsal skin and fingernails on the volar aspect of the hand: an unusual anatomic deformity.

A very unusual hand malformation is reported in which dorsal skin and nails exist on the volar aspect of the hands. This patient also exhibits mental retardation and microcephaly as well as a partial deletion of chromosome 6. Fifty percent of a small series of patients previously reviewed who presented with chromosome 6 abnormalities demonstrated abnormalities of the hands. Unusual deformities of the hands associated with mental retardation and microcephaly may be related to an abnormality of chromosome 6.

Chromosome Aberrations↗

PubMedDate not supplied

Long-term outcome in treated combined methylmalonic acidemia and homocystinemia.

PURPOSE: To describe the clinical and biochemical features and long-term outcome of a cohort of eight patients with methylmalonic acidemia and homocystinuria (cblC). METHODS: Documentation of clinical features at birth and longitudinal follow-up of the biochemical and clinical response to treatment with daily oral carnitine and intramuscular hydroxocobalamin observed during continuous follow-up for an average of 5.7 years. RESULTS: Our patients had an increased incidence of congenital malformations including microcephaly (<5%) at birth (2 of 8), congenital heart disease (2 of 8), dysmorphic facial features (1 of 8), and thyroglossal duct cyst (1 of 8). Postnatal hydrocephalus (2 of 8) and hip dislocation caused by ligament laxity (1 of 8) were also noted. One patient had profound visual impairment before 6 months of age secondary to cblC retinopathy, and two patients had abnormal retinal pigmentation with normal visual function. All patients presented with poor growth, feeding problems, and/or seizures. No patients had acute acidotic crises before or after treatment. All patients had dramatic reduction of plasma free homocystine and urine methylmalonic acid excretion after initiation of therapy with carnitine, intramuscular (IM) hydroxocobalamin (OHcbl) and, in two cases, oral betaine. Growth was significantly improved in most cases after the initiation of therapy, and microcephaly was resolved in one patient. All patients were developmentally delayed regardless of age of treatment onset, although two patients had relatively mild developmental delay. CONCLUSION: cblC patients may have an increased incidence of congenital malformations suggesting prenatal effects of abnormal cbl metabolism. Treatment with IM OHcbl and carnitine successfully corrects the biochemical abnormalities and improves growth. Developmental delay of variable severity is always present regardless of age at diagnosis or treatment onset.

Adolescent↗

PubMed2005

Pregnancy and neonatal outcomes in women with eating disorders.

OBJECTIVE: This study was initiated to examine pregnancy and neonatal outcomes in women with past or current eating disorders as compared with a control group. METHODS: Forty-nine nulliparous nonsmoking women previously diagnosed with eating disorders (24 anorexia nervosa, 20 bulimia nervosa, 5 eating disorders not otherwise specified) and 68 controls were recruited in early pregnancy. Data on antenatal complications, mode of delivery, and neonatal outcome variables were collected. For comparisons between groups 1-way analysis of variance or chi(2) test was used. RESULTS: Twenty-two percent of the patients had a verified relapse in eating disorders during pregnancy. Women with past or current eating disorders were at increased risk of hyperemesis (P < .01) and delivered infants with significantly lower birth weight (P < .01) and smaller head circumference (P < .001) as compared with controls. They were also at greater risk of delivering infants with microcephaly (P < .05) and small for gestational age infants (P < .05). CONCLUSION: Pregnant women with past or active eating disorders seem to be at greater risk for delivering infants with lower birth weight, smaller head circumference, microcephaly, and small for gestational age. LEVEL OF EVIDENCE: II-2.

Adult↗