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Ataxia-telangiectasia (A-T) is an autosomal recessive neurodegenerative disorder with multisystem involvement and cancer predisposition, caused by mutations in the A-T mutated (ATM) gene. To study genotype-phenotype correlations, we evaluated the clinical and laboratory data of 51 genetically proven A-T patients, and additionally measured ATM protein expression and kinase activity. Patients without ATM kinase activity showed the classical phenotype. The presence of ATM protein, correlated with slightly better immunological function. Residual kinase activity correlated with a milder and essentially different neurological phenotype, absence of telangiectasia, normal endocrine and pulmonary function, normal immunoglobulins, significantly lower X-ray hypersensitivity in lymphocytes, and extended lifespan. In these patients, cancer occurred later in life and generally consisted of solid instead of lymphoid malignancies. The genotypes of severely affected patients generally included truncating mutations resulting in total absence of ATM kinase activity, while patients with milder phenotypes harbored at least one missense or splice site mutation resulting in expression of ATM with some kinase activity. Overall, the phenotypic manifestations in A-T show a continuous spectrum from severe classical childhood-onset A-T to a relatively mild adult-onset disorder, depending on the presence of ATM protein and kinase activity. Each patient is left with a tremendously increased cancer risk., (© 2011 Wiley Periodicals, Inc.)

We describe two sisters (ages 10 and 3 years, respectively) with a normal development and a combination of congenital sensorineural hearing loss, partial agenesis of the corpus callosum, arachnoid cyst, and hydrocephalus. Neither girl has distinctive physical anomalies. In the oldest girl, there was a hearing loss of 80 dB bilaterally, and the most severe loss on audiogram was seen at 2,000-4,000 Hz. In the youngest girl, there was a hearing loss of 100 dB bilaterally. Above 2,000 Hz no neural reactions were seen. Cerebral magnetic resonance imaging in one girl and computed tomography in the other showed a partial agenesis of the corpus callosum and a cyst in the pineal region, causing an aqueduct stenosis by compression and consequent hydrocephalus. The parents have normal hearing, and brain magnetic resonance imaging showed no abnormalities. They are nonconsanguineous but from the same small village. This is the first report of a combination of congenital sensorineural hearing loss, partial agenesis of the corpus callosum, and an arachnoid cyst. The pattern of inheritance is probably autosomal recessive., (Copyright 1999 Wiley-Liss, Inc.)

The clinical findings in 12 Angelman syndrome (AS) patients (4 sib pairs and 4 sporadic cases, aged 12-55 years) without a cytogenetic or molecular detectable defect at the AS locus were compared to those of 28 AS patients (aged 11-50 years) with a deletion, in order to determine whether the clinical spectrum differed between the two groups. There were only two minor differences, i.e., mandibular prognathism was always found in the patients with a defect (100% vs. 58%), whereas truncal hypotonia was found less frequently in the group with a detectable genetic defect (54% vs. 91%). All other clinical and physical characteristics were equally represented in the two groups. Epileptic seizures occurred in 93% and 75%, respectively, of patients with and without a detectable chromosome 15 defect. Specific EEG patterns were found in 90% of both groups. The clinical signs and symptoms of our patients closely resemble those in familial AS cases reported in the literature, with the exception of scoliosis, which was present in 55% of the patients in our study. We conclude that the absence of a detectable cytogenetic or molecular defect at the AS locus is not associated with a strikingly different AS phenotype, compared to those with such a defect. Mutation analysis of the UBE3A gene in our patients without a detectable genetic defect, especially in the familial cases, is currently underway.

We studied the clinical and EEG-findings in 28 adult patients (aged 20-53 years) with Angelman syndrome (AS). Twenty-three showed a maternal chromosome 15q11-13 deletion; in 5, the diagnosis was based on a combination of typical clinical findings. Compared to the clinical manifestations present in childhood, "coarsening" of facial traits (100%), thoracic scoliosis (71%), and being wheelchair-bound (39%) were found more frequently. Paroxysms of laughter were still observed in adulthood (79%), but less frequently than in childhood. Most adult patients could feed themselves, but needed help with many daily activities. The majority (82%) had epileptic seizures. Abnormal EEG-activity consisting of 2-3/s rhythmic triphasic waves of high amplitude with a maximum over the frontal regions, which has been identified in many AS children, was found in 67% of these adult patients.