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Microcephaly and simplified gyral pattern of the brain associated with early onset insulin-dependent diabetes mellitus.

Two families are presented with a child suffering from microcephaly with a simplified gyral pattern of the brain (SGP) and early onset insulin dependent diabetes mellitus (IDDM). The first patient was diagnosed postmortally with Wolcott-Rallison syndrome, after her younger brother developed IDDM, and a homozygous mutation in the eukaryotic translation initiation factor 2-alpha kinase 3 was found. The younger brother did not undergo magnetic resonance imaging (MRI). The patient from the second family has no EIF2AK3 mutation. SGP is considered to arise from decreased neuronal proliferation or increased apoptosis at an early stage of embryonal development, but insight into the pathways involved is minimal. EIF2AK3 is involved in translation initiation. It has been proposed that loss of function mutations reduce the ability of the cell to respond to endoplasmic reticulum stress, resulting in apoptosis of pancreatic Langerhans cells. Our findings suggest that in some cases, early onset IDDM and SGP can arise from common mechanisms leading to increased apoptosis.

Age of Onset↗

Nail aplasia, microcephaly, severe mental retardation and MRI abnormalities: report of two unrelated cases.

We present the clinical and laboratory features of two unrelated mentally retarded females with sporadic bilateral periventricular nodular heterotopia (BPNH), hypoplastic/absent nails and other malformative features. Clinical examination, MRI scanning, EEG recording, karyotyping and neuropsychological testing were performed. From a molecular genetic point of view, direct sequencing analysis, X-inactivation assay and telomere analysis were carried out in one patient. The two patients showed convincing similarities from clinical and neuroradiological points of view with BPNH, mental retardation, microcephaly and hypoplastic/absent nails of fingers and toes. Our two unrelated mentally retarded females may be affected by complex malformative syndromes sharing some common features such as BPNH, mental retardation and hypoplastic/absent nails. Further genetic studies are needed to better understand the pathogenetic bases of this neurological disease. These two cases widen the spectrum of BPNH-associated syndromes.

Abnormalities, Multiple↗

Twin-twin transfusion with abrupt onset of microcephaly in the surviving recipient following spontaneous death of the donor twin.

We describe a case in which twin-twin transfusion with fetal death of the donor at 23 weeks was complicated by suspected intracranial embolic insult of the surviving recipient twin. Dynamic transient intracranial ultrasonographic findings were noted with complete resolution by 28 weeks. Subsequent severe microcephaly of the survivor with no further growth of any of the cranial parameters beyond 25 weeks was thought to be a result of this very unusual pathophysiologic mechanism.

Adult↗

Inherited syndrome of microcephaly, dyskinesia and pontocerebellar hypoplasia: a systemic atrophy with early onset.

A neurodegenerative disease is reported in 5 related families, belonging to a Dutch genetic isolate. Seven children (5 females, 2 males) had microcephaly, spastic pareses, severe extrapyramidal dyskinesia and failure to acquire any voluntary skills. Four died during childhood. Marked pontocerebellar hypoplasia and progressive cerebral atrophy were found by computed tomography of the brain. Autopsy in one case revealed widespread, progressive loss of neurons affecting the olivopontoneocerebellar system more severely than any other part of the brain, accounting for the macroscopic pontocerebellar hypoplasia. A neocortical biopsy from another patient indicated that rough endoplasmic reticulum in neurons as the earliest ultrastructural target of the pathological process. This study confirms the disease as an inherited neuronal degeneration with very early, probably prenatal onset.

Atrophy↗

An increased risk for malignant neoplasms in heterozygotes for a syndrome of microcephaly, normal intelligence, growth retardation, remarkable facies, immunodeficiency and chromosomal instability.

We have collected and studied the genealogical data of 8 patients with the autosomal recessive syndrome of microcephaly, normal intelligence, immunodeficiency, risk of malignancy and chromosomal instability resembling ataxia telangiectasia (AT), but different in complementation group. 50% of our probands died from lymphoreticular malignancies in early childhood. We have found a significantly increased incidence of malignant tumors in 142 blood relatives as compared with a control group of 87 spouses. All patients belonged to the same complementation group differing from the 5 known AT complementation groups, which seems to be in general more malignant than all other groups of AT. From this standpoint our material is homogeneous in contrast to other similar studies in AT families. We think this syndrome represents another model to examine the relationship between genetic background, chromosomal abnormalities, immunodeficiency and cancer development.

Adult↗

Cernunnos, a novel nonhomologous end-joining factor, is mutated in human immunodeficiency with microcephaly.

DNA double-strand breaks (DSBs) occur at random upon genotoxic stresses and represent obligatory intermediates during physiological DNA rearrangement events such as the V(D)J recombination in the immune system. DSBs, which are among the most toxic DNA lesions, are preferentially repaired by the nonhomologous end-joining (NHEJ) pathway in higher eukaryotes. Failure to properly repair DSBs results in genetic instability, developmental delay, and various forms of immunodeficiency. Here we describe five patients with growth retardation, microcephaly, and immunodeficiency characterized by a profound T+B lymphocytopenia. An increased cellular sensitivity to ionizing radiation, a defective V(D)J recombination, and an impaired DNA-end ligation process both in vivo and in vitro are indicative of a general DNA repair defect in these patients. All five patients carry mutations in the Cernunnos gene, which was identified through cDNA functional complementation cloning. Cernunnos/XLF represents a novel DNA repair factor essential for the NHEJ pathway.

Adolescent↗

X-linked mental retardation, short stature, microcephaly and hypogonadism maps to Xp22.1-p21.3 in a Belgian family.

X-linked mental retardation (XLMR) is a heterogeneous disorder that can be classified as either non-specific (MRX), when mental retardation is the only feature, or as syndromic mental retardation (MRXS). Genetic defects underlying XLMR are being identified at a rapid pace, often starting from X-chromosomal aberrations and XLMR families with a well-defined linkage interval. Here, we present a new family with a syndromic form of XLMR, including mild mental retardation, short stature, microcephaly and hypogonadism. Two-point linkage analysis with 24 polymorphic markers spanning the entire X chromosome was carried out. We could assign the causative gene to a 6 cM interval in Xp22.1-p21.3, with a maximum LOD score of 2.61 for markers DXS989 and DXS1061 at theta = 0.00. No mutations were found in the presented family for two known MRX genes mapping to this interval, ARX and IL1RAPL-1. These data indicate that the interval Xp22.1-p21.3 contains at least one additional MRXS gene.

Adult↗

A 6Mb deletion in band 2q22 due to a complex chromosome rearrangement associated with severe psychomotor retardation, microcephaly and distinctive dysmorphic facial features.

High-resolution analyses of complex chromosome rearrangements (CCR) have demonstrated in individuals with abnormal phenotypes that not all seemingly balanced CCRs based on G-banding are completely balanced at breakpoint level. Here we report on an apparently balanced de novo CCR involving chromosomes 2, 3 and 5 present in a 6-month-old girl. She was referred for genetic evaluation because of severe psychomotor retardation, distinctive dysmorphic features and microcephaly. A 1Mb resolution array-CGH analysis of DNA from the patient revealed a deletion of about 6Mb for chromosome 2. FISH analysis showed that the deletion interval found in band 2q22 mapped at the translocation breakpoint, and that the ZFHX1B gene, which is known to be involved in the Mowat-Wilson syndrome, is located within the deletion interval. To our knowledge this is the first case of a complex chromosomal rearrangement associated with Mowat-Wilson syndrome. Our data illustrate the important role for high-resolution investigation of apparently balanced chromosome rearrangements in patients with unexplained psychomotor retardation and/or other clinical features, and should contribute to our understanding of the mechanisms involved in chromosome rearrangement.

Chromosome Breakage↗

Hereditary spastic paraparesis with distal muscle wasting, microcephaly, mental retardation, arachnodactyly and tremors: new entity?

We present a consanguineous Pakistani family in which four patients (two males and two females) had a new Troyer-like phenotype. All four patients showed some marfanoid features (span more than height, arachnodactyly, high arched palate), and generalized hyper-reflexia. The two affected males and the younger female also had microcephaly and mental retardation. Features only present in the affected males included short stature, dysarthria, amyotrophy of the distal muscles, fasciculations and tremor. The distal muscle wasting in the two affected brothers reflected the presence of axonal neuropathy demonstrated both electrophysiologically and by nerve biopsy. Although neither of the sisters had any degree of distal muscle wasting, both had reduced M-wave amplitude of the tibial and peroneal nerves, bilaterally. The described phenotype does not fit any of the recognized forms of hereditary spastic paraparesis with distal muscle wasting. The specific axonal neuropathy differentiates it from familial motor neuron disease with mental retardation. The reported phenotype represents a possible new Troyer-like syndrome similar to that described by Neuhäuser (1976), but differs from it by the lack of major dysmorphic features.

Adolescent↗

Pathologic and laboratory correlation in microcephaly associated with prenatal cocaine exposure.

The Authors report a case where cocaine abuse during pregnancy assessed by drug analysis at various site was associated with foetal microcephaly. Foetal pathologic findings revealed anomalies in neuronal migration and in the vascular architecture in the brain. Such anomalies might be the result of prolonged exposure to cocaine in utero, aggravated by the high concentration of cocaine metabolites in the amniotic fluid over a prolonged period.

Abnormalities, Drug-Induced↗

Methodologic issues in epidemiologic studies of congenital microcephaly.

In this methodological paper, we explore a number of issues that pose problems for those who seek the antecedents of congenital microcephaly. We pay particular attention to three concerns: Who is a case? How should cases be classified? To whom should cases be compared?

Epidemiologic Methods↗

Adenylosuccinase deficiency: an unusual cause of early-onset epilepsy associated with acquired microcephaly.

Adenylosuccinase deficiency, an autosomal recessive inborn error of purine synthesis, was first described in 1984 by Jaeken and Van den Berghe (reviewed in J Inher Metab Dis 20;1997:193). The cardinal features are variable psychomotor delay often accompanied by epilepsy and autistic features. Diagnosis is made by detection of abnormal purine metabolites in body fluids. We report a girl who presented with early onset epilepsy, associated with acquired microcephaly and severe psychomotor retardation, as the most prominent symptoms.

Adenylosuccinate Lyase↗

Microcephaly with plate-like cortical calcification.

Congenital malformations of the central nervous system have varied presentations depending on the stage of embryological development when the insult occurred. We report a neonate with microcephaly associated with plate-like cortical calcification, probably secondary to an unidentified insult at around 11-12 weeks post-conceptional age causing an arrest of the proliferative phase. The associated vasculopathy probably caused diffuse cortical calcification.

Brain Diseases↗

Three siblings of fatal infantile encephalopathy with olivopontocerebellar hypoplasia and microcephaly.

We report three male siblings born with fatal encephalopathy comprising microcephaly, myoclonus and muscle hypertonia. All three patients died during infancy. Postmortem examination on the brain revealed that all infants had neuronal loss in the cerebellar cortex, inferior olivary and pontine nuclei, which were more pronounced in the older subject than the younger ones. In addition, they were associated with polymicrogyria in the cerebral cortex of the insula, olivary and dentate nuclear dysplasia, and a hypoplastic corticospinal tract. The clinical and neuropathological findings in our cases were identical to those in fatal infantile encephalopathy with olivopontocerebellar hypoplasia and microencephaly [Albrecht et al., Acta Neuropathol 1993;85:394-399], but an association of malformations suggests a new genetic factor in pathogenesis of olivopontocerebellar hypoplasia.

Abnormalities, Multiple↗

Merosin-positive congenital muscular dystrophy with mental retardation, microcephaly and central nervous system abnormalities unlinked to the Fukuyama muscular dystrophy and muscular-eye-brain loci: report of three siblings.

Classical merosin (2 laminin)-positive congenital muscular dystrophy is a heterogeneous subgroup of disorders; a few cases characterized by severe mental retardation, brain involvement and no ocular abnormalities were called Fukuyama-like congenital muscular dystrophy. We report a family of healthy non-consanguineous parents, with four affected siblings, of which one died at the age of 7 months due to an intercurrent illness, who presented congenital hypotonia, severe mental retardation, microcephaly, delayed psychomotor development, generalized muscular wasting and weakness with mild facial involvement, calf pseudohypertrophy, joint contractures and areflexia. Muscle biopsy disclosed severe muscular dystrophy. Immunostaining for laminin 2 80 kDa and clone Mer3/22B2 monoclonal antibodies, 1 and 1 chain was preserved. Magnetic resonance imaging findings were consistent with pontocerebellar hypoplasia, bilateral opercular abnormalities and focal cortical dysplasia as well as minute periventricular white matter changes. Clusters of small T2-weighted focal hyperintensities in both cerebellar hemispheres consistent with cysts were observed in two of the three siblings studied with magnetic resonance imaging. Ophthalmologic and cardiologic examination was normal. Haplotype analysis using microsatellite markers excluded the Fukuyama congenital muscular dystrophy, LAMA2 and muscle-eye-brain disease loci. Thus, a wider spectrum of phenotypes, gene defects and protein deficiencies might be involved in congenital muscular dystrophy with brain abnormalities.

Biopsy↗

Congenital microcephaly and seizures due to 3-phosphoglycerate dehydrogenase deficiency: outcome of treatment with amino acids.

Congenital microcephaly, intractable seizures and severe psychomotor retardation characterize 3-phosphoglycerate dehydrogenase (3-PGDH) deficiency, a disorder of L-serine biosynthesis. The enzyme defect results in low concentrations of serine and to a variable degree of glycine in plasma and cerebrospinal fluid. Short-term beneficial effects have been reported of oral treatment with the deficient amino acids. In this paper, we report the first follow-up data of amino acid therapy in five patients treated for 3-7.5 years. Different treatment regimes were used, but a favourable response to amino acids was observed in all patients. A major reduction in seizure frequency occurred in all patients; two patients became free of seizures. Amino acids were well tolerated and no adverse effects were documented. A progress of psychomotor development was only observed in one patient, diagnosed early and treated with a high dosage of L-serine. A favourable outcome of 3-PGDH deficiency depends on early diagnosis and treatment.

Carbohydrate Dehydrogenases↗

A de novo complex chromosomal rearrangement with nine breakpoints characterized by FISH in a boy with mild mental retardation, developmental delay, short stature and microcephaly.

A de novo complex chromosome rearrangement (CCR) involving chromosomes 1, 6, 7, 15 and Y was detected in a boy with mental retardation, short stature, and microcephaly. Fluorescence in situ hybridisation (FISH) with whole chromosome painting libraries, band-specific cosmids and telomeric probes was essential for the characterisation of the rearrangement. The CCR was shown to be the result of at least nine chromosomal breaks and involved the alternating insertion of two segments of the short arm of chromosome 1 and two segments of the long arm of chromosome 6 into a novel derived chromosome 7. A non-reciprocal translocation between the distal short arm of the same chromosome 7 and the distal long arm of the Y chromosome was also found, together with a paracentric inversion of the long arm of chromosome 15. The only detectable imbalance was a deletion of the heterochromatic Yq telomeric region. FISH investigations in this case have revealed an additional complexity in this CCR, which has implications for reproductive risk assessment and genetic counselling.

Body Height↗

MEHMO (mental retardation, epileptic seizures, hypogonadism and -genitalism, microcephaly, obesity), a novel syndrome: assignment of disease locus to xp21.1-p22.13.

A previously unrecognised X-chromosomal mental retardation syndrome is described. Clinical hallmarks are mental retardation, epileptic seizures, hypogonadism, and -genitalism, microcephaly and obesity. Life expectancy of patients is less than two years. Based on the major clinical symptoms this condition is referred to by the acronym MEHMO. Haplotype and two-point linkage analyses in a large three-generation family assign the disease locus to Xp21.1-p22.13, to a region that is flanked by CYBB and DXS365.

Epilepsy↗