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A two base pair deletion in the PQBP1 gene is associated with microphthalmia, microcephaly, and mental retardation.

X-linked mental retardation has been traditionally divided into syndromic (S-XLMR) and non-syndromic forms (NS-XLMR), although the borderlines between these phenotypes begin to vanish and mutations in a single gene, for example PQBP1, can cause S-XLMR as well as NS-XLMR. Here, we report two maternal cousins with an apparently X-linked phenotype of mental retardation (MR), microphthalmia, choroid coloboma, microcephaly, renal hypoplasia, and spastic paraplegia. By multipoint linkage analysis with markers spanning the entire X-chromosome we mapped the disease locus to a 28-Mb interval between Xp11.4 and Xq12, including the BCOR gene. A missense mutation in BCOR was described in a family with Lenz microphthalmia syndrome, a phenotype showing substantial overlapping features with that described in the two cousins. However, no mutation in the BCOR gene was found in both patients. Subsequent mutation analysis of PQBP1, located within the delineated linkage interval in Xp11.23, revealed a 2-bp deletion, c.461_462delAG, that cosegregated with the disease. Notably, the same mutation is associated with the Hamel cerebropalatocardiac syndrome, another form of S-XLMR. Haplotype analysis suggests a germline mosaicism of the 2-bp deletion in the maternal grandmother of both affected individuals. In summary, our findings demonstrate for the first time that mutations in PQBP1 are associated with an S-XLMR phenotype including microphthalmia, thereby further extending the clinical spectrum of phenotypes associated with PQBP1 mutations.

Abnormalities, Multiple↗

Riga-Fede disease: association with microcephaly.

A case of microcephaly associated with traumatic ulceration to the ventral surface of the tongue (Riga-Fede disease) in a 12-month-old female is presented. To the best of our knowledge, such association has not been described previously. A conservative treatment regime was used, involving medical management, elimination of the sharp edges of the teeth and use of topical triamcinolone, and the ulceration healed over a period of 4 weeks.

Anti-Inflammatory Agents↗

MRI of the brain in the Cohen syndrome: a relatively large corpus callosum in patients with mental retardation and microcephaly.

Our purpose was to perform the first systematic brain magnetic resonance imaging (MRI) study of a substantial number of Cohen syndrome (MIM n:o 216550) patients. 18 Cohen patients and 26 healthy volunteers were examined by MRI (1.0 T). All Cohen patients had essential features of this syndrome: typical facial and structural features, mental retardation, microcephaly, ophthalmologic symptoms, granulocytopenia and cheerful psychic disposition. All our patients belong to the recently published study of refined mapping of the Cohen syndrome gene by linkage disequilibrium. As visual analysis of MR images revealed an impression of a large corpus callosum (CC), quantitative analysis was performed. Sagittal diameter of the body of the CC was larger than that of controls (p = 0.02), whereas all sagittal diameters of the brain stem were markedly smaller (p < 0.0001), as was the midline internal skull surface (MISS) (p < 0.0001). The CC surface did not significantly differ from that of controls significantly. Our main finding, a relatively enlarged corpus callosum, has not previously been reported to associate with mental retardation. Though MRI alone can not confirm the diagnosis and no definite measurements can be recommended for clinical use, any clinical suspicion of this syndrome receives reinforcement through MRI: a relatively enlarged corpus callosum in a microcephalic head and normal signal intensities of the grey and white matters.

Abnormalities, Multiple↗

Autosomal recessive microcephaly, mental retardation with nonpigmentary retinopathy and a distinctive electroretinogram.

The association of microcephaly and mental retardation with a non-pigmentary retinopathy is described in three siblings of consanguineous parents. The electroretinogram showed the distinctive appearance of markedly attenuated "b" wave but normal "a" wave suggestive of a retinal dystrophy primarily affecting post-receptoral elements in the inner retina. This appears to be an autosomal recessive condition which has not been previously reported.

Child↗

Celiac disease presenting with microcephaly.

A 15-month-old girl with celiac disease presented with microcephaly and developmental delay. Head growth resumed during a gluten-free diet. Subsequent gluten ingestion resulted in no head growth, areflexia, and increased celiac antibodies. All resolved with gluten elimination. Poor head growth may precede other clinical manifestations of celiac disease.

Celiac Disease↗

A fifth locus for primary autosomal recessive microcephaly maps to chromosome 1q31.

Primary microcephaly is a genetic disorder in which an affected individual has a head circumference >3 SDs below the age- and sex-related mean. A small but apparently normally formed brain is the reason for the reduced head circumference, and, probably because of this, all affected individuals are mentally retarded. The condition is genetically heterogeneous, and four loci have already been identified. We now report a fifth locus, MCPH5, which is an 8-cM region mapping to chromosome 1q31, defined by the markers GATA135F02 and D1S1678.

Adult↗

Premature chromosome condensation in humans associated with microcephaly and mental retardation: a novel autosomal recessive condition.

We report a novel autosomal recessive disorder characterized by premature chromosome condensation in the early G2 phase. It was observed in two siblings, from consanguineous parents, affected with microcephaly, growth retardation, and severe mental retardation. Chromosome analysis showed a high frequency of prophase-like cells (>10%) in lymphocytes, fibroblasts, and lymphoblast cell lines with an otherwise normal karyotype. (3)H-thymidine-pulse labeling and autoradiography showed that, 2 h after the pulse, 28%-35% of the prophases were labeled, compared with 9%-11% in healthy control subjects, indicating that the phenomenon is due to premature chromosome condensation. Flow cytometry studies demonstrate that the entire cell cycle is not prolonged, compared with that in healthy control subjects, and compartment sizes did not differ from those in healthy control subjects. No increased reaction of the cells to X-irradiation or treatments with the clastogens bleomycin and mitomycin C was observed, in contrast to results in the cell-cycle mutants ataxia telangiectasia and Fanconi anemia. The rates of sister chromatid exchanges and the mitotic nondisjunction rates were inconspicuous. Premature entry of cells into mitosis suggests that a gene involved in cell-cycle regulation is mutated in these siblings.

Cell Cycle↗

Leucodysplasia, microcephaly, cerebral malformation (LMC): a novel recessive disorder linked to 2p16.

We report three related and one unrelated child with an apparently novel neurodevelopmental disorder. The clinical course was very similar in all the four patients: congenital microcephaly with severe failure of post-natal brain growth, neonatal onset of intractable seizures associated with lack of developmental progression and death within the first 3 years of life. The appearance on cerebral neuroimaging was almost identical, with simplified gyration associated with a non-thickened cortex, severe hypoplasia of the corpus callosum, a small flattened brain stem, and specific cystic lesions in the white matter around the temporal and occipital horns. To our knowledge these patients represent a previously unreported, autosomal recessive syndrome. Homozygosity mapping in the consanguineous family has identified a candidate region on the chromosome 2p16.

Abnormalities, Multiple↗

The microcephaly ASPM gene is expressed in proliferating tissues and encodes for a mitotic spindle protein.

The most common cause of primary autosomal recessive microcephaly (MCPH) appears to be mutations in the ASPM gene which is involved in the regulation of neurogenesis. The predicted gene product contains two putative N-terminal calponin-homology (CH) domains and a block of putative calmodulin-binding IQ domains common in actin binding cytoskeletal and signaling proteins. Previous studies in mouse suggest that ASPM is preferentially expressed in the developing brain. Our analyses reveal that ASPM is widely expressed in fetal and adult tissues and upregulated in malignant cells. Several alternatively spliced variants encoding putative ASPM isoforms with different numbers of IQ motifs were identified. The major ASPM transcript contains 81 IQ domains, most of which are organized into a higher order repeat (HOR) structure. Another prominent spliced form contains an in-frame deletion of exon 18 and encodes 14 IQ domains not organized into a HOR. This variant is conserved in mouse. Other spliced variants lacking both CH domains and a part of the IQ motifs were also detected, suggesting the existence of isoforms with potentially different functions. To elucidate the biochemical function of human ASPM, we developed peptide specific antibodies to the N- and C-termini of ASPM. In a western analysis of proteins from cultured human and mouse cells, the antibodies detected bands with mobilities corresponding to the predicted ASPM isoforms. Immunostaining of cultured human cells with antibodies revealed that ASPM is localized in the spindle poles during mitosis. This finding suggests that MCPH is the consequence of an impairment in mitotic spindle regulation in cortical progenitors due to mutations in ASPM.

Adult↗

Sporadic trichodental dysplasia with microcephaly and mental retardation.

Trichodental syndrome is a rare autosomal dominant ectodermal dysplasia. Hair and dental anomalies have been found in different combinations in most affected persons in three families. The features of trichodental syndrome were observed in a young female in which sparse, fine, lustreless and slow growing hairs were associated with bigeminismus of inferior lateral incisors. Ultrastructural hair analysis showed consistent variation in contour of the shaft and reduced to absent cuticular scale. Distinguishing features in this patient were microcephaly and mild mental retardation.

Child, Preschool↗

Extreme microcephaly, severe growth and mental retardation, flexion contractures, and ichthyotic skin in two brothers: a new syndrome or mild form of Neu-Laxova syndrome?

Two brothers with congenital microcephaly, growth and mental retardation, flexion contractures, dorsal edema of hands and feet, and ichthyotic skin changes are described. Mild manifestations of Neu-Laxova syndrome have to be considered but long survival and only mild intrauterine growth retardation not described in this syndrome may be evidence of a different condition.

Contracture↗

Mandibulofacial dysostosis, microcephaly and thorax deformities in two brothers: a new recessive syndrome?

We report two brothers who presented with mandibulofacial dysostosis, growth retardation, microcephaly, thoracic deformities and conductive hearing loss along with asplenia in one case and aplasia of the gallbladder in the other. The pattern of malformations differs significantly from established syndromes with mandibulofacial dysostosis such as Nager syndrome or Genée-Wiedemann syndrome and also from cerebro-costo-mandibular syndrome. As chromosome analysis revealed normal male karyotypes, we consider this to be a distinct heritable syndrome that may be either autosomal recessive or X-chromosomal recessive.

Abnormalities, Multiple↗

Male siblings with dyserythropoiesis, microcephaly and intrauterine growth retardation.

Male siblings with intrauterine growth retardation, hydrops, mild liver dysfunction, chronic diarrhoea, failure to thrive and microcephaly are reported. In both patients, the intrauterine growth retardation was detected in the second trimester of pregnancy. Relatively severe early onset neonatal jaundice, microcytosis, anisocytosis and abnormal iron metabolism were also seen. Bone marrow examination in the second sibling showed marked ringed sideroblasts and multilobulated erythroblasts in late developmental stages. The brain was very small with enlarged cerebrospinal fluid space, a reduced number of gyri and a thin cortex. The clinical and laboratory findings in these patients appear to be unique.

Anemia, Dyserythropoietic, Congenital↗

Microcephaly, lissencephaly, Hirschsprung disease and tetralogy of Fallot: a new syndrome?

We report an 8-month-old girl with extreme microcephaly, lissencephaly, tetralogy of Fallot and Hirschsprung disease. She has a history of infantile spasms with developmental stagnation. Various diagnoses were considered but none seem to fit her clinical presentation. This combination of findings has not been described in the past and we suggest that this may be a previously undescribed neurodevelopmental syndrome resulting from a global failure of neuronal migration.

Adult↗

Microcephaly, distinctive facies, single atrium, postaxial polydactyly, skeletal defects and mental retardation: a new familial faciocardiomelic syndrome?

Three siblings with postaxial polydactyly type A, congenital heart defect (single atrium), mental retardation, microcephaly, a distinctive facial appearance, skeletal anomalies and neonatal macrosomy were studied. Comparison with other cardiomelic syndromes previously described in the literature lead us to conclude that this is a new faciocardiomelic syndrome probably inherited as an autosomal recessive trait.

Abnormalities, Multiple↗