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PubMed2004

Effect of high maternal blood phenylalanine on offspring congenital anomalies and developmental outcome at ages 4 and 6 years: the importance of strict dietary control preconception and throughout pregnancy.

OBJECTIVES: The Maternal Phenylketonuria Study was designed to determine the effect of a phenylalanine (Phe)-restricted diet in reducing the morbidity on the fetus. Congenital abnormalities were noted, with the focus on the effect of congenital heart defects (CHDs) and microcephaly (MICRO) on developmental outcome at 4 and 6 years of age. STUDY DESIGN: Women with blood Phe levels >240 micromol/L (n=526; to convert micromol/L to mg/dL, divide by 60) were enrolled; 382 contributed 572 pregnancies. The women had 413 offspring examined at birth and annually. At 4 years, the McCarthy General Cognitive Index was administered, and at 6 years, the Wechsler Intelligence Scale for Children Revised was administered. RESULTS: Microcephaly was noted in 137 (33%) of the offspring, and 32 (7.7%) had CHD. Maternal blood Phe levels were higher for infants with CHD and MICRO than for infants with CHD only (P=.02). Mean Phe levels at 4 to 8 weeks gestation predicted CHD (P<.0001). The McCarthy General Cognitive Index score was lower with CHD (P=.005) and MICRO (P=.0017), as was the Wechsler Intelligence Scale for Children Revised full-scale IQ score (P=.0002 for CHD and P=.0001 for MICRO). None of the subjects who had offspring with CHD had Phe control between 120 and 360 micromol/L during the first 8 to 10 weeks of gestation. CONCLUSIONS: Women with phenylketonuria need to be educated regarding diet for life. This should help improve diet control before conception and throughout pregnancy.

Abnormalities, Multiple↗

PubMed2004

Altered synaptic activities in cultures of neocortical neurons from prenatally X-irradiated rats.

Prenatal X-irradiation can induce severe microcephaly in the brains of offspring. The possible alteration of neuronal synapse formation was examined in such X-irradiated rats with microcephaly using the whole-cell current clamp technique. The total number of neocortical cells from prenatally (E16) X-irradiated rats decreased to 16% of the control value, while the ratio of GABA-positive/MAP2-positive neurons increased 2.2-fold. Neocortical neurons from E17 normal rat fetuses cultured on monolayers of astrocytes for 7-10 days exhibited synchronized synaptically-driven rhythmic depolarizing potentials (RDPs). Neocortical neurons from prenatally (E15 or E16) X-irradiated rats also exhibited synchronized RDPs, however, their amplitude and the number of spikes decreased. These results suggest that, although neurons which survive in X-irradiated rats can form synapses, inhibitory inputs are predominant over excitatory inputs. It is possible that not only acute neuronal loss induced by X-irradiation but also increased inhibitory inputs in neocortex give rise to subsequent neurological disorders in X-irradiated rats.

Action Potentials↗

PubMed2000

[Feingold syndrome].

BACKGROUND: Feingold syndrome is a combination of hand and foot anomalies, microcephaly, tracheo-esophageal fistula, esophageal/duodenal atresia, short palpebral fissures and developmental delay. The most frequent physical findings are clinodactyly of the second and fifth fingers with absent or hypoplastic middle phalanges, and syndactyly of the toes. Inheritance is autosomal dominant (MIM number 164280) with full penetrance concerning hand anomalies, variable expressivity and great intrafamilial variability. CASE REPORT: We report the case of an African boy with duodenal atresia, microcephaly, brachymesophalangy of the second and fifth fingers, unilateral thumb hypoplasia, bilateral syndactyly of toes 2-3 and amesophalangy of the toes. Karyotype was normal. No other member of the family was affected. A fresh mutation is possible. CONCLUSION: Brachymesophalangy affecting mainly the second and fifth fingers and amesophalangy of the lateral toes are cardinal clinical findings in Feingold syndrome. These clinical findings define the syndrome of brachydactyly A4-Temtamy type (MIM 112800), suggesting that brachydactyly A4 would be a partially expressed Feingold syndrome. The incidence of esophageal/duodenal atresia is 29%, including all the known cases. All karyotypes of reported patients were normal.

Abnormalities, Multiple↗

PubMed2004

Congenital disorder of glycosylation (CDG) type Ie. A new patient.

CDG Ie is caused by a deficiency of dolichol-phosphate-mannose synthase 1 (DPM1), an enzyme involved in N-glycan assembly in the endoplasmic reticulum. Three proteins are known to be part of the synthase complex: DPM 1, DPM2 and DPM3. Only mutations in DPM1, the catalytic subunit, have been described in three families. One was homozygous for the c274C>G (R92G) mutation in DPM1 and two others were compound heterozygous for R92G and a c628delC deletion or a c331-343del13, respectively. Clinical features were a severe infantile encephalopathy, early intractable seizures, acquired microcephaly, and some dysmorphic features. We report a patient with milder symptoms: microcephaly, dysmorphic features, developmental delay, optic atrophy, and cerebellar dysfunction without cerebellar atrophy. The patient is homozygous for a new mutation in exon 9 of the DPM1 gene (c742T>C (S248P)). Our findings extend the spectrum of CDG Ie.

Brain↗

PubMed1994

Kidney in Galloway-Mowat syndrome: clinical spectrum with description of pathology.

The Galloway-Mowat syndrome, a rare inherited disorder, is characterized by congenital microcephaly with hypotonia and developmental delay, often hiatus hernia, and nephrotic syndrome manifested in infancy or in early childhood. The glomerular lesion has been poorly characterized in the few previous reports of this syndrome. We studied three siblings with microcephaly and nephrotic syndrome occurring during the first two weeks of life. Hematuria, glycosuria and renal failure were also present. Renal biopsy and postmortem specimens of two patients were studied. Glomerular structure was disorganized; capillary lumina were of varying calibers, capillary walls were adherent to one another, and mesangial zones were poorly demarcated. Glomerular basement membrane ultrastructure was markedly altered. The normal trilaminar structure was obscured or replaced by flocculent material; furthermore, 6 to 8 nm fibrils of unknown nature permeated the space between endothelial and epithelial cells. Non-glomerular basement membranes were unaltered in appearance. This syndrome apparently represents, in part, a new disorder of glomerular basement membrane formation and function.

Basement Membrane↗

PubMed2005

Genetic links between brain development and brain evolution.

The most defining biological attribute of Homo sapiens is its enormous brain size and accompanying cognitive prowess. How this was achieved by means of genetic changes over the course of human evolution has fascinated biologists and the general public alike. Recent studies have shown that genes controlling brain development - notably those implicated in microcephaly (a congenital defect that is characterized by severely reduced brain size) - are favoured targets of natural selection during human evolution. We propose that genes that regulate brain size during development, such as microcephaly genes, are chief contributors in driving the evolutionary enlargement of the human brain. Based on the synthesis of recent studies, we propose a general methodological template for the genetic analysis of human evolution.

Animals↗

PubMed2003

Bilateral pheochromocytomas and congenital anomalies associated with a de novo germline mutation in the von Hippel-Lindau gene.

A 12-year-old boy presented with severe hypertension, congenital microcephaly, severe hearing loss, developmental delay, cryptorchidism, and bilateral pheochromocytomas, without the phenotypic features of multiple endocrine neoplasia type II syndromes (MEN-2). Sequence analysis of the polymerase chain reaction (PCR)-amplified gnomic DNA identified a missense mutation at nucleotide 451 of the von Hippel-Lindau (VHL) gene (A451G) that changes a codon for serine (AGT) to one for glycine (GGT) at amino acid position 80 (S80G). The sequence DNA analysis of the parents did not show a mutation in the VHL gene that was previously identified in their affected son. The observed constellation of microcephaly, deafness, cryptorchidism, developmental delay, hypertension, and bilateral pheochromocytoma in association with a VHL mutation A451G in a patient with negative family history has not previously been described in the literature. Knowledge that VHL mutation plays a critical role in sporadic pheochromocytoma should aid in the future diagnosis and treatment of this tumor. Genetic testing in known pheochromocytoma families is indicated to identify genetically abnormal subjects that carry the MEN-2, VHL, and glomus tumor gene mutations.

Adrenal Gland Neoplasms↗

PubMed2003

Eating difficulties in girls with Rett syndrome compared with other developmental disabilities.

Rett syndrome arises from a mutation on the X chromosome and occurs with prevalence in the general population in 1:10,000 women. Its major nutritional consequences require that health providers recognize early signs of eating difficulties and slowing of growth parameters. Retrospective record review of 44 girls, in two equal-sized groups matched by age, showed that the Rett syndrome group was significantly different, with lower body weights, more respiratory difficulties, more gastrointestinal symptoms interfering with eating, more swallowing problems, less self-feeding, and lower texture tolerance for chewy and crunchy foods compared with the developmental disability group. Microcephaly was noted for half of the Rett syndrome group compared with seven in the developmental disability group. Parents expressed concern about their child's difficulties in eating; eight of the Rett syndrome girls and 13 of the girls in the developmental disability group were reported to have a poor appetite. Distinctive features of Rett syndrome consistent with those in the literature were documented reasonably well in the nutrition assessment records. Detailed food intake information was analyzed for food texture characteristics to recognize early eating and texture tolerance problems. Recommendations were offered for conducting a thorough nutrition assessment of Rett syndrome patients, including analysis of the texture of consumed foods. Additional recommendations for improving nutrition services to those with Rett syndrome and other developmental disabilities include ruling out microcephaly, early identification of eating difficulties, with modifications in food texture as appropriate, and self-feeding goals.

Anthropometry↗

PubMed1977

[Children of mothers with phenylketonuria (author's transl)].

Microcephaly and considerable motor and mental retardation occurred in two non-phenylketonuric children of an untreated mother with phenylketonuria. The cerebral damage of the children must be considered the consequence of the maternal metabolic disorder. Since the first phenylketonuric children who were treated on strict diet are now reaching the age of marriage and pregnancy, the problem of maternal phenylketonuria is becoming topical. Published reports indicate that of 72 well documented cases with a maternal phenylalanine level above 200 mg/1 (1210 mumol/1) 39 offspring had microcephaly, in 33 intra-uterine growth had been retarded and in 25 there are cerebral palsy and seizures. Almost all had mental retardation. At the same time there have been reports about three normal children whose mothers had kept to a phenylalanine-low diet during their pregnancy.

Adolescent↗

PubMed2000

Hypomyelination and reversible white matter attenuation in 3-phosphoglycerate dehydrogenase deficiency.

White matter abnormalities are a feature of many inborn errors of metabolism and magnetic resonance imaging (MRI) of the brain has become an important tool in the diagnostic work-up of these disorders. Recently, patients were reported with a potentially treatable disorder of serine biosynthesis. They presented with congenital microcephaly, severe psychomotor retardation and intractable seizures. Low concentrations of the amino acids serine, glycine as well as 5-methyltetrahydrofolate were found in plasma and CSF and were due to a deficiency of the enzyme 3-phosphoglycerate dehydrogenase (3-PGDH). We studied four patients aged 10 months to 7 years by MRI before and after treatment with amino acids with a follow-up of 16 months to 6 years. Magnetic resonance spectroscopy (MRS) was performed in two patients at 4 and 16 months of treatment. Pre-treatment MRI demonstrated hypomyelination and profound white matter attenuation in all patients. During treatment, a significant increase in white matter volume was found and a progress of myelination in two patients. The most striking finding on MRS during treatment was an elevated level of white matter choline. Serine biosynthesis defects have to be considered in the differential diagnosis of patients with mental retardation, microcephaly, seizures, and on MRI hypomyelination and white matter attenuation.

Amino Acids↗

PubMed2005

Late-onset nephrotic syndrome and severe cerebellar atrophy in Galloway-Mowat syndrome.

Galloway-Mowat syndrome (GMS) is a rare autosomal-recessive disorder characterised by nephrotic syndrome, microcephaly, and variable brain anomalies. The prognosis is poor with death almost inevitably supervening before the age of 6 years, but atypical cases with later onset of proteinuria and a more protracted course are on record. We report a female offspring from consanguineous parents suffering from microcephaly, profound psychomotor retardation, epilepsy, hiatal hernia, and striking cerebellar atrophy in whom a nephrotic syndrome became apparent at age 16 years. Renal biopsy revealed focal segmental glomerulosclerosis and glomerular basement membrane abnormalities. We postulate that this patient had a milder form of GMS with severe and diffuse cerebellar atrophy as the leading central nervous system abnormality.

Adolescent↗

PubMed1999

Neurological and psychological findings in patients with Cohen syndrome: a study of 18 patients aged 11 months to 57 years.

Our purpose was to perform the first systematic neurological, neurophysiological and psychological study of 18 patients with Cohen syndrome (MIM no 216550), aged 11 months to 57 years (median 27 years). All the patients had the essential features of this syndrome, i.e., typical facial and structural findings, mental retardation, microcephaly, ophthalmologic symptoms, granulocytopenia and a cheerful psychic disposition. Children with the syndrome were considered normal at birth, but upwards of 6 to 12 months, psychomotor retardation became obvious. The first symptoms were microcephaly, which manifested itself by the age of 6 months to 1 year, as well as hypotonia and delayed developmental milestones. Cohen children learned to walk at 2 to 5 years of age. Language development varied markedly. Neurological symptoms did not progress. All patients had normal EMGs. The three youngest (aged 11 months, 3 and 5 years) had normal EEGs, whereas the remainder had low-voltage EEGs. No irritative spikes or epileptoformic foci were found. Nine patients had quick beta transients. Of the 18 patients examined, 4 were profoundly, 11 severely, 1 moderately and 2 mildly retarded. On the AADM scale, Cohen patients had high scores in the positive domains, viz., self-direction, responsibility and socialisation. Maladaptive behaviour, on the other hand, was almost completely absent, except for stereotyped behaviours and odd mannerisms. Withdrawal, sexually aberrant behaviour, untrustworthy and rebellious behaviour as well as antisocial behaviour were rare. These findings are consistent with the cheerful and sociable disposition characteristic of those with Cohen syndrome.

Activities of Daily Living↗

PubMed2001

Early predictors of neurodevelopmental outcome in symptomatic congenital cytomegalovirus infection.

OBJECTIVE: To determine the ability of neonatal clinical, audiologic, and computed tomography (CT) findings to predict long-term neurodevelopmental outcome in children with symptomatic congenital cytomegalovirus (CMV) infection. METHODS: Longitudinal cohort study of children (n = 41) with symptomatic congenital CMV infection evaluated at birth and followed up with serial age-appropriate neurodevelopmental testing. The performance of birth characteristics as predictors of long-term outcome were determined, and clinical and CT scoring systems were developed and correlated with intellectual outcome. RESULTS: Microcephaly was the most specific predictor of mental retardation (100%; 95% CI 84.5-100) and major motor disability (92.3%; 95% CI 74.8-99). An abnormality detected by CT was the most sensitive predictor for mental retardation (100%; 95% CI 82.3-100) and motor disability (100%; 95% CI 78.2-100). A highly significant (P <.001) positive correlation was found between head size at birth and the intelligence/developmental quotient (IQ/DQ). Approximately 29% of children had an IQ/DQ >90. There was no association between sensorineural hearing loss at birth and cognitive outcome. However, children with sensorineural hearing loss on follow-up (congenital and late-onset) had a lower IQ/DQ (P =.006) than those with normal hearing. CONCLUSIONS: The presence of microcephaly at birth was the most specific predictor of poor cognitive outcome in children with symptomatic congenital CMV infection, whereas children with normal findings on head CT and head circumference proportional to weight exhibited a good cognitive outcome.

Cerebral Palsy↗

PubMed2002

Identification of microcephalin, a protein implicated in determining the size of the human brain.

Primary microcephaly (MIM 251200) is an autosomal recessive neurodevelopmental condition in which there is a global reduction in cerebral cortex volume, to a size comparable with that of early hominids. We previously mapped the MCPH1 locus, for primary microcephaly, to chromosome 8p23, and here we report that a gene within this interval, encoding a BRCA1 C-terminal domain-containing protein, is mutated in MCPH1 families sharing an ancestral 8p23 haplotype. This gene, microcephalin, is expressed in the developing cerebral cortex of the fetal brain. Further study of this and related genes may provide important new insights into neocortical development and evolution.

Adolescent↗

PubMed2004

Allelic heterogeneity in the COH1 gene explains clinical variability in Cohen syndrome.

Cohen syndrome is a rare autosomal recessive disorder with a variable clinical picture mainly characterized by developmental delay, mental retardation, microcephaly, typical facial dysmorphism, progressive pigmentary retinopathy, severe myopia, and intermittent neutropenia. A Cohen syndrome locus was mapped to chromosome 8q22 in Finnish patients, and, recently, mutations in the gene COH1 were reported in patients with Cohen syndrome from Finland and other parts of northern and western Europe. Here, we describe clinical and molecular findings in 20 patients with Cohen syndrome from 12 families, originating from Brazil, Germany, Lebanon, Oman, Poland, and Turkey. All patients were homozygous or compound heterozygous for mutations in COH1. We identified a total of 17 novel mutations, mostly resulting in premature termination codons. The clinical presentation was highly variable. Developmental delay of varying degree, early-onset myopia, joint laxity, and facial dysmorphism were the only features present in all patients; however, retinopathy at school age, microcephaly, and neutropenia are not requisite symptoms of Cohen syndrome. The identification of novel mutations in COH1 in an ethnically diverse group of patients demonstrates extensive allelic heterogeneity and explains the intriguing clinical variability in Cohen syndrome.

Abnormalities, Multiple↗

PubMed2006

Periventricular heterotopia: phenotypic heterogeneity and correlation with Filamin A mutations.

Periventricular heterotopia (PH) occurs when collections of neurons lay along the lateral ventricles or just beneath. Human Filamin A gene (FLNA) mutations are associated with classical X-linked bilateral periventricular nodular heterotopia (PNH), featuring contiguous heterotopic nodules, mega cisterna magna, cardiovascular malformations and epilepsy. FLNA encodes an F-actin-binding cytoplasmic phosphoprotein and is involved in early brain neurogenesis and neuronal migration. A rare, recessive form of bilateral PNH with microcephaly and severe delay is associated with mutations of the ADP-ribosylation factor guanine nucleotide-exchange factor-2 (ARFGEF2) gene, required for vesicle and membrane trafficking from the trans-Golgi. However, PH is a heterogeneous disorder. We studied clinical and brain MRI of 182 patients with PH and, based on its anatomic distribution and associated birth defects, identified 15 subtypes. Classical bilateral PNH represented the largest group (98 patients: 54%). The 14 additional phenotypes (84 patients: 46%) included PNH with Ehlers-Danlos syndrome (EDS), temporo-occipital PNH with hippocampal malformation and cerebellar hypoplasia, PNH with fronto-perisylvian or temporo-occipital polymicrogyria, posterior PNH with hydrocephalus, PNH with microcephaly, PNH with frontonasal dysplasia, PNH with limb abnormalities, PNH with fragile-X syndrome, PNH with ambiguous genitalia, micronodular PH, unilateral PNH, laminar ribbon-like and linear PH. We performed mutation analysis of FLNA in 120 patients, of whom 72 (60%) had classical bilateral PNH and 48 (40%) other PH phenotypes, and identified 25 mutations in 40 individuals. Sixteen mutations had not been reported previously. Mutations were found in 35 patients with classical bilateral PNH, in three with PNH with EDS and in two with unilateral PNH. Twenty one mutations were nonsense and frame-shift and four missense. The high prevalence of mutations causing protein truncations confirms that loss of function is the major cause of the disorder. FLNA mutations were found in 100% of familial cases with X-linked PNH (10 families: 8 with classical bilateral PNH, 1 with EDS and 1 with unilateral PH) and in 26% of sporadic patients with classical bilateral PNH. Overall, mutations occurred in 49% of individuals with classical bilateral PNH irrespective of their being familial or sporadic. However, the chances of finding a mutation were exceedingly gender biased with 93% of mutations occurring in females and 7% in males. The probability of finding FLNA mutations in other phenotypes was 4% but was limited to the minor variants of PNH with EDS and unilateral PNH. Statistical analysis considering all 42 mutations described so far identifies a hotspot region for PNH in the actin-binding domain (P < 0.05).

Abnormalities, Multiple↗

PubMed2004

Reconstructing the evolutionary history of microcephalin, a gene controlling human brain size.

The defining process in the evolution of primates and particularly humans is the dramatic expansion of the brain. While many types of genes could potentially contribute to this process, genes that specifically regulate brain size during development may be especially relevant. Here, we examine the evolution of the microcephalin gene, whose null mutation in humans causes primary microcephaly, a congenital defect characterized by severe reductions in brain size without other gross abnormalities. We show that the evolution of microcephalin's protein sequence is highly accelerated throughout the lineage from simian ancestors to humans and chimpanzees, with the most pronounced acceleration seen in the early periods of this lineage. We further demonstrate that this accelerated evolution is coupled with signatures of positive selection. Statistical analysis suggests that about 45 advantageous amino acid changes in microcephalin might have fixed during the 25-30 million years of evolution from early simian progenitors to modern humans. These observations support the notion that the molecular evolution of microcephalin may have contributed to brain expansion in the simian lineage leading to humans. We have recently shown that ASPM, another gene linked to primary microcephaly, experienced strong positive selection in the ape lineage leading to humans. We therefore propose that genes regulating brain size during development may have the general propensity to contribute to brain evolution in primates and particularly humans.

Animals↗

PubMed2006

Normal variants of Microcephalin and ASPM do not account for brain size variability.

Normal human brain volume is heritable. The genes responsible for variation in brain volume are not known. Microcephalin (MCPH1) and ASPM (abnormal spindle-like microcephaly associated) have been proposed as candidate genes as mutations in both genes are associated with microcephaly, and common variants of each gene are apparently under strong positive selective pressure. In 120 normal subjects, we genotyped these variants and measured brain volumes using magnetic resonance imaging. We found no evidence that the selected alleles were associated with increases or decreases in brain volume. This result suggests that the selective pressure on these genes may be related to subtle neurobiological effects or to their expression outside the brain.

Adolescent↗