We observed two unrelated consanguineous families with malformation syndromes sharing anophthalmia and distinct eyebrows as common signs, but differing for alveolar capillary dysplasia or complex congenital heart defect in one and diaphragmatic hernia in the other family. Homozygosity mapping revealed linkage to a common locus on chromosome 15, and pathogenic homozygous mutations were identified in STRA6, a member of a large group of "stimulated by retinoic acid" genes encoding novel transmembrane proteins, transcription factors, and secreted signaling molecules or proteins of largely unknown function. Subsequently, homozygous STRA6 mutations were also demonstrated in 3 of 13 patients chosen on the basis of significant phenotypic overlap to the original cases. While a homozygous deletion generating a premature stop codon (p.G50AfsX22) led to absence of the immunoreactive protein in patient's fibroblast culture, structural analysis of three missense mutations (P90L, P293L, and T321P) suggested significant effects on the geometry of the loops connecting the transmembrane helices of STRA6. Two further variations in the C-terminus (T644M and R655C) alter specific functional sites, an SH2-binding motif and a phosphorylation site, respectively. STRA6 mutations thus define a pleiotropic malformation syndrome representing the first human phenotype associated with mutations in a gene from the "STRA" group.
Pontocerebellar hypoplasias (PCH) represent a group of neurodegenerative autosomal recessive disorders with prenatal onset, atrophy or hypoplasia of the cerebellum, hypoplasia of the ventral pons, microcephaly, variable neocortical atrophy and severe mental and motor impairments. In two subtypes, PCH2 and PCH4, we identified mutations in three of the four different subunits of the tRNA-splicing endonuclease complex. Our findings point to RNA processing as a new basic cellular impairment in neurological disorders.
ABSTRACT. Objectives. To further define the clinical spectrum of the disease for pediatric and metabolic spe cialists, and to suggest that the general pediatrician and pediatric neurologist consider succinic semialdehyde de hydrogenase (SSADH) deficiency in the differential di agnosis of patients with (idiopathic) mental retardation and emphasize the need for accurate, quantitative or ganic acid analysis in such patients.Patients. The clinical features of 23 patients (20 fam ilies) with SSADH deficiency (4-hydroxybutyric acid uria) are presented. The age at diagnosis ranged from 3
The following study describes the discovery of a new inherited metabolic disorder, dolichol kinase (DK1) deficiency. DK1 is responsible for the final step of the de novo biosynthesis of dolichol phosphate. Dolichol phosphate is involved in several glycosylation reactions, such as N-glycosylation, glycosylphosphatidylinositol (GPI)-anchor biosynthesis, and C- and O-mannosylation. We identified four patients who were homozygous for one of two mutations (c.295T-->A [99Cys-->Ser] or c.1322A-->C [441Tyr-->Ser]) in the corresponding hDK1 gene. The residual activity of mutant DK1 was 2%-4% when compared with control cells. The mutated alleles failed to complement the temperature-sensitive phenotype of DK1-deficient yeast cells, whereas the wild-type allele restored the normal growth phenotype. Affected patients present with a very severe clinical phenotype, with death in early infancy. Two of the patients died from dilative cardiomyopathy.
This series increases the limited knowledge of mutations and phenotypes of this rare disorder. Mutation analysis of the CaSR gene facilitates patient and family management. Low dosages of calcitriol resulted in less frequent renal calcifications.
Cutis laxa is characterised by redundant, inelastic skin with deep wrinkling and additional variable systemic involvement. Mutations in fibulin-4 (EFEMP2) and fibulin-5 (FBLN5) were described to be causative for autosomal recessive cutis laxa type 1 in a few families each. The female patient was born to healthy consanguineous parents. Pregnancy was remarkable for fetal overgrowth and oligohydramnios. The newborn girl showed extreme bradycardia and died perinatally. Apart from overgrowth, cutis laxa, arachnodactyly of hands and feet with contractures of the third to fifth finger, medial rotation of feet, spina bifida of the os sacrum, microcephaly and facial dysmorphism were noted. Autopsy showed collapsed lungs with hypoplastic diaphragm and signs of cervical soft tissue bleedings due to fragility of vessels. Histologic examination showed fragmentation of elastic fibres with formation of cystic cavities in the medial layer of the aorta and central lung vessels. Sequencing of the elastin, fibulin-4 and fibulin-5 genes revealed a homozygous missense mutation (p.Cys267Tyr) in the fibulin-4 gene in the patient. Our observation increases the number of cases with fibulin-4 mutations to three and extends the phenotypic spectrum of fibulin-4 mutations by microcephaly, overgrowth and arachnodactyly.
In a population with no general varicella vaccination programme, varicella accounted for a small but not negligible risk for death in immunocompetent and immunocompromised children. Together these data point to the importance of a thoroughly implemented, general varicella vaccination programme.
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