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Biomedical subjects

M Baraitser

Publications and source records attributed to M Baraitser.

194 records · Page 11Linked to original sources
PubMed1981

Intrafamilial correlation in Friedreich's ataxia.

The distribution of age of onset and age of losing the ability to walk independently in patients with Friedreich's ataxia from 93 sibships are presented. Intrafamilial correlation was investigated using three methods: the Pearson product-moment correlation coefficient and to estimates of correlation based on analysis of variance, one a maximum likelihood method and the other using a weighted mean family size. All three resulted in correlation coefficients (r) of around 0.5 for both disease parameters. The latter two methods yielded similar values just greater than 0.5 and it is considered that these are more reliable estimates of intraclass correlation as there were a variable number of family members in the sibships studied. Although the examination of intraclass correlation in Friedreich's ataxia was not highly suggestive of genetic heterogeneity, the observed proportion of first cousin marriages amongst the parents of the sibships studied was about twice the expected proportion. Overall, the data would be compatible with genetic heterogeneity if one genotype is more prevalent than others. An alternative hypothesis is that there are different modifying genes operating within different families in which Friedreich's ataxia occurs.

Adolescent↗
PubMed1981

Biochemical and clinical studies of Friedreich's ataxia.

A series of biochemical tests aimed at elucidating the fundamental cause has been applied to 20 patients with Friedreich's ataxia. Special emphasis was placed upon pyruvate metabolism. The results demonstrate no precisely identifiable defect in the metabolism of pyruvate but indicate an abnormality in glucose uptake and metabolism.

Adolescent↗
PubMed1980

The incidence and nature of visual pathway involvement in Friedreich's ataxia. A clinical and visual evoked potential study of 22 patients.

Pattern-reversal visual evoked potentials (VEP) were recorded from 22 patients (mean age 33.7 years) with Friedreich's ataxia, 15 of whom also had a detailed neuro-ophthalmological assessment prior to the VEP examination. None had noted symptomatic visual impairment. Eleven of the 15 (73 per cent) examined clinically had one or more neuro-ophthalmic abnormality and 14/22 (64 per cent) had an abnormal VEP study which was always binocular and comprised absent responses, or most commonly, increased P100 component latencies. The maximum P100 latency was 143 ms and the group mean was 118 ms. The P100 amplitude was also generally reduced particularly in those patients with latencies less than 115 ms (upper limit of normal), while in those with latencies above the normal range there was a significant inverse correlation between the P100 amplitude and latency. The waveform, temporal dispersion and interocular differences were normal in almost all patients with identifiable responses, including those with prolonged VEP latencies. Electroretinograms recorded from three selected patients were either normal or minimally abnormal and suggested secondary rather than primary retinal involvement. The only VEP parameter to correlate with either the duration of the generalized disease or the visual acuity was the P100 amplitude. A good correlation was found between the VEP and the clinical neuro-ophthalmic findings. Temporal pallor of the optic disc was most often associated with an abnormal VEP result and impaired visual acuity or colour vision were uncommon in the absence of VEP abnormalities. The VEP changes and those obtained from 24 age- and acuity-matched cases of demyelinating optic neuritis are contrasted and the probable pathophysiology is discussed. Two main conclusions emerge from this study. First, there is a high incidence of asymptomatic visual pathway involvement in Friedreich's ataxia which can be demonstrated by both clinical and VEP examination. Secondly, the VEP changes in Friedreich's ataxia differ from those found in typical demyelinating optic neuropathy and are consistent with progressive nerve fibre loss and associated slowing of conduction, indicating that the visual pathway is affected by the same widespread process of axonal degeneration found throughout the nervous system.

Adult↗
PubMed1980

Organic acidurias and amino acidurias in the aetiology of long-term mental handicap.

In order to evaluate the contribution of patients with organic aciduria and amino acidopathies to populations with severe long-term mental handicap, urine from a total of 1,778 such patients from four hospitals has been examined for organic acids and amino acids. The patients have been classified into eight groups according to the nature of their handicap. It is concluded that, apart from phenylketonuria originating from before dietary treatment was available, known inherited metabolic diseases do not contribute significantly to the incidence of mental handicap in the population studied.

Amino Acid Metabolism, Inborn Errors↗
PubMed1980

Sialidosis type 2 (acid neuraminidase deficiency): clinical and biochemical features of a further case.

A further patient with a presumed primary deficiency of sialidase N-acetylneuraminic acid hydrolase EC 3.2.1.18) is described. Clinically the patient falls into the sialidosis type 2 category of the recent classification of Lowden & O'Brien (1979), i.e. he manifests coarse facies, mental retardation and skeletal changes of dysostosis multiplex as well as myoclonus and a cherry-red spot at the macula. Sialidase activity in fibroblasts was 4% of control values using a methylumbelliferone substrate. The father of the patient was found to have 50% activity. Abnormal amounts of sialyloligosaccharides were found in the urine. The electrophoretic mobility of known glycosylated enzymes and proteins was found to be altered (more anodal than usual), but could be corrected by incubation of the cell extracts with bacterial neuraminidase. The relationship of the present patient to the Lowden & O'Brien classification is discussed.

Abnormalities, Multiple↗
PubMed1980

Pitfalls of genetic counselling in Pfeiffer's syndrome.

A family with Pfeiffer's syndrome is presented in which members of two generations showed only partial but relevant syndactyly before a child was born, in the third generation, with the full acrocephalosyndactyly syndrome.

Acrocephalosyndactylia↗
PubMed1980

Peripheral and central somatosensory nerve conduction defects in Friedreich's ataxia.

Somatosensory evoked potentials were recorded over the clavicle, cervical spine, mastoid processes and the hand area of the contralateral somatosensory cortex to median nerve stimulation in 22 cases of Friedreich's ataxia. There was a marked attenuation of the clavicular potential, but little evidence of delay of this or the major cervical component. A dispersed and delayed cortical response was therefore suggestive of slowed conduction in central pathways. The cortical response was shown to be mediated by peripheral fibres with normal conduction velocity between stimulation sites at the wrist and the elbow.

Adolescent↗
PubMed1978

Genetic study of narcoleptic syndrome.

In this family study of the narcoleptic syndrome, 52% of the probands had an affected first degree relative, 41.9% of the sibs of those probands with an affected parent were similarly affected, 33.3% of the parents of 2 affected sibs and 41.2% of the children (after a correction for age) had narcolepsy, cataplexy, or both.

Age Factors↗
PubMed1977

Genetics of Möbius syndrome.

A study of the sibs and parents of 15 children diagnosed as having the Möbius syndrome suggests that the inclusion of primary skeletal defects as obligatory in the diagnosis of the syndrome helps to exclude the high risk monogenic disorders of muscle and anterior horn cell, which present with a Möbius-like facies in infancy.

Abducens Nerve↗
PubMed1976

Axonal velocities of motor units in the hand and foot muscles of the baboon.

The axonal velocities of single motor units in the small hand and foot muscles of the baboon were studied by means of a collision technique which produced selective blocking of most of the fast-conducting fibres. In the abductor pollicis brevis muscle velocities ranged from 43 to 82 m/sec, and in the abductor digiti minimi muscle from 40 to 78 m/sec. In the extensor digitorum brevis muscle the range was 40-70 m/sec. When velocities were plotted as percentages of the maximal obtained in the same experiment, the range was similar in the 3 muscles studied. Most motor units had velocities greater than 65% of maximal but, in a few, velocities were between 55% and 65% of maximal. The possible relevance of these findings to human motor nerves is discussed.

Animals↗
PubMedDate not supplied

Prenatal treatment of fetal hydrops associated with the hypertelorism-dysphagia syndrome (Opitz-G syndrome).

Non-immunological fetal hydrops diagnosed prenatally presents a difficult diagnostic and therapeutic problem. In the case presented, fetal hydrops was recognized at 19 weeks gestation and no specific cause was found prenatally in spite of extensive investigations. The fetal hydrops was treated in utero by thoracocentesis and an intravenous infusion of albumin carried out at fetoscopy. After birth the infant was recognized to have the hypertelorism-dysphagia syndrome (or Opitz-G syndrome, McK no. 30710). This autosomal dominant syndrome consists of hypertelorism, laryngeal abnormalities, swallowing difficulties, hyprospadias and an imperforate anus. Fetal hydrops has been reported on one previous occasion in this syndrome. The intrauterine treatment given in this case may have been successful in reducing the neonatal complications of the Opitz-G syndrome.

Adult↗
PubMedDate not supplied

Absent right atrioventricular connection and double-inlet ventricle due to an unbalanced familial 8:13 chromosome translocation: a cautionary tale.

A two-year-old child who had had palliative surgery as a neonate for an absent right atrioventricular connection and double-inlet ventricle was shown to be developmentally retarded. Trisomy for the short arm of chromosome 8 was demonstrated, resulting from a familial 8:13 translocation, with a high risk of recurrence. Although the specific features of this case are unique, it illustrates the importance of chromosome analysis in any dysmorphic infant whose heart defect places prolonged survival in doubt.

Cardiac Catheterization↗