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Biomedical subjects

J L Tolmie

Publications and source records attributed to J L Tolmie.

At least 19 recordsLinked to original sources

Coats' plus: a progressive familial syndrome of bilateral Coats' disease, characteristic cerebral calcification, leukoencephalopathy, slow pre- and post-natal linear growth and defects of bone marrow and integument.

In 1988 we reported two sisters with bilateral Coats' disease, sparse hair, dystrophic nails, and primeval splashes of intracranial calcification. We now provide an update on this family documenting the occurrence of skeletal defects comprising abnormal bone marrow, osteopenia, and sclerosis with a tendency to fractures, a mixed cerebellar and extrapyramidal movement disorder, infrequent epileptic seizures, leukodystrophic changes, and postnatal growth failure. Additionally, we present two previously unreported individuals from Ireland and Switzerland with the identical disorder which we designate Coats' plus. Since our original publication a number of other authors have described, frequently as a "new" syndrome, cases with a variable combination of the same features observed in our patients. We review this literature and suggest that the phenotypic overlap with dyskeratosis congenita may provide a clue to the molecular aetiology of this multisystem disorder.

Alopecia↗

The Southwest of Scotland Structural Chromosomal Abnormalities Database: an assessment of its contribution to genetic counselling in affected families.

AIM: To assess the effect of establishing a genetic database on the provision of genetic counselling to individuals and families with structural chromosomal abnormalities. METHOD: For the four year period 1997-2000, we compared all cytogenetics laboratory records with entries on the database to determine its completeness. We assessed the extent to which families had been followed up, compared these findings with a previous four year period (1977-1980) and sought to discover why some families were not followed up. RESULTS: Of 215 probands identified during 1997-2000, 19 (9%) were not recorded on the register. Approximately one third of families were followed up completely, one third were partially followed up and one third had had no follow-up, for a variety of reasons. In this last group, there was evidence that some had received inadequate or incorrect genetic advice. There was no evidence that the database improved follow-up in families with structural chromosome abnormalities. Over 20 years, there has been a downward trend in the proportion of cases referred to the genetic clinic. CONCLUSIONS: Our register can be used to monitor trends in clinical practice but has had no direct effect on the service provided to patients and their families.

Chromosome Aberrations↗

Cleft palate, hypotelorism, and hypospadias: Schilbach-Rott syndrome.

A mother and two sons have cleft palate and facial appearance closely resembling cases described by Schilbach and Rott in 1988. One of the two males has hypospadias and learning disability and, like his mother, is of short stature. The family described by Schilbach and Rott also supports an autosomal dominant inheritance pattern.

Adolescent↗

Mutations in the general transcription factor TFIIH result in beta-thalassaemia in individuals with trichothiodystrophy.

The transcription factor TFIIH is involved in both basal transcription and DNA repair. Mutations in the XPD helicase component of TFIIH can result in the diverse clinical features associated with xeroderma pigmentosum (XP) and trichothiodystrophy (TTD). It is generally believed that the multi-system abnormalities associated with TTD are the result of a subtle deficiency in basal transcription. However, to date, there has been no clear demonstration of a defect in expression of any specific gene in individuals with these syndromes. Here we show that the specific mutations in XPD that cause TTD result in reduced expression of the beta-globin genes in these individuals. Eleven TTD patients with characterized mutations in the XPD gene have the haematological features of beta-thalassaemia trait, and reduced levels of beta-globin synthesis and beta-globin mRNA. All these parameters were normal in three patients with XP. These findings provide the first evidence for reduced expression of a specific gene in TTD. They support the hypothesis that many of the clinical features of TTD result from inadequate expression of a diverse set of highly expressed genes.

Cells, Cultured↗

A new case of Myhre syndrome.

Myhre Syndrome is a rare condition associated with mental retardation, short stature, generalized muscle hypertrophy, cardiac defects and a distinct facial appearance. There have only been five reported cases and we now present a sixth, together with a review of the clinical features of this syndrome.

Abnormalities, Multiple↗

A novel acropectoral syndrome maps to chromosome 7q36.

F syndrome (acropectorovertebral syndrome) is a dominantly inherited skeletal dysplasia affecting the hands, feet, sternum, and lumbosacral spine, which has previously been described in only two families. Here we report a six generation Turkish family with a related but distinct dominantly inherited acropectoral syndrome. All 22 affected subjects have soft tissue syndactyly of all fingers and all toes and 14 also have preaxial polydactyly of the hands and/or feet. In addition, 14 have a prominent upper sternum and/or a blind ending, inverted U shaped sinus in the anterior chest wall. Linkage studies and haplotype analysis carried out in 16 affected and nine unaffected members of this family showed that the underlying locus maps to a 6.4 cM interval on chromosome 7q36, between EN2 and D7S2423, a region to which a locus for preaxial polydactyly and triphalangeal thumb-polysyndactyly has previously been mapped. Our findings expand the range of phenotypes associated with this locus to include total soft tissue syndactyly and sternal deformity, and suggest that F syndrome may be another manifestation of the same genetic entity. In mice, ectopic expression of the gene Sonic hedgehog (Shh) in limb buds and lateral plate mesoderm during development causes preaxial polydactyly and sternal defects respectively, suggesting that misregulation of SHH may underlie the unusual combination of abnormalities in this family. A recently proposed candidate gene for 7q36 linked preaxial polydactyly is LMBR1, encoding a novel transmembrane receptor which may be an upstream regulator of SHH.

Abnormalities, Multiple↗

Aicardi-Goutières syndrome displays genetic heterogeneity with one locus (AGS1) on chromosome 3p21.

We have studied 23 children from 13 families with a clinical diagnosis of Aicardi-Goutières syndrome. Affected individuals had developed an early-onset progressive encephalopathy that was characterized by a normal head circumference at birth, basal ganglia calcification, negative viral studies, and abnormalities of cerebrospinal fluid comprising either raised white cell counts and/or raised levels of interferon-alpha. By means of genomewide linkage analysis, a maximum-heterogeneity LOD score of 5.28 was reached at marker D3S3563, with alpha=.48, where alpha is the proportion of families showing linkage. Our data suggest the existence of locus heterogeneity in Aicardi-Goutières syndrome and highlight potential difficulties in the differentiation of this condition from pseudo-TORCH (toxoplasmosis, rubella, cytomegalovirus, and herpes simplex virus types 1 and 2) syndrome.

Abnormalities, Multiple↗

The molecular basis of malonyl-CoA decarboxylase deficiency.

We characterized a 2.1-kb human cDNA with a 1362-bp (454-amino acid) open reading frame showing 70.3% amino acid identity to goose malonyl-CoA decarboxylase (MCD). We have identified two different homozygous mutations in human MCD (hMCD) by using RT-PCR analysis of fibroblast RNA from two previously reported consanguineous Scottish patients with MCD deficiency. The first mutation is a 442C-->G transversion resulting in a premature stop codon (S148X) in the N-terminal half of the protein. The second is a 13-bp insertion in the mature RNA, causing a frameshift with predicted protein truncation. This insertion is the result of an intronic mutation generating a novel splice acceptor sequence (IVS4-14A-->G). Both mutations were found to segregate appropriately within the families and were not found in 100 normal unrelated individuals. These mutations would be predicted to cause MCD deficiency, thus confirming this transcript as the hMCD ortholog. The peptide sequence of hMCD revealed a C-terminal peroxisomal targeting sequence (-SKL). This targeting signal appears to be functional in vivo, since the distribution of MCD enzymatic activity in rat liver homogenates-as measured by means of subcellular fractionation-strongly suggests that MCD is localized to peroxisomes in addition to the mitochondrial localization reported elsewhere. These data strongly support this cDNA as encoding human MCD, an important regulator of fatty acid metabolism.

Adolescent↗

Towards earlier diagnosis of 22q11 deletions.

Over a 7 year period, 551 patients were investigated for the presence of a chromosome 22q11 deletion by fluorescence in situ hybridisation. Analysis of the presenting features of the 67 individuals with this chromosome deletion permitted us to devise guidelines to facilitate early diagnosis.

Abnormalities, Multiple↗

Two sisters with prenatal growth failure, disproportionate short stature, and feeding difficulties.

A familial short stature syndrome is described in two sisters. Clinical features include severe pre- and post-natal growth failure, stridor, feeding difficulties in the first 2 years requiring nasogastric feeding and facial dysmorphism reminiscent of Three M syndrome. Intellectual function is normal. Skeletal surveys show short long bones, small square iliac bones, short femoral necks and vertebral bodies which are short in the antero-posterior diameter with narrowing of the interpedicular distance inferiorly.

Bone Diseases, Developmental↗

Mosaic supernumerary ring chromosome 19 identified by comparative genomic hybridisation.

We report the use of comparative genomic hybridisation (CGH) to define the origin of a supernumerary ring chromosome which conventional cytogenetic banding and fluorescence in situ hybridisation (FISH) methods had failed to identify. Targeted FISH using whole chromosome 19 library arm and site specific probes then confirmed the CGH results. This study shows the feasibility of using CGH for the identification of supernumerary marker chromosomes, even in fewer than 50% of cells, where no clinical or cytogenetic clues are present.

Aged↗

"Cataplexy" and muscle ultrasound abnormalities in Coffin-Lowry syndrome.

The Coffin-Lowry syndrome is a rare cause of mental retardation recognised by its distinctive facial and digital features. We have observed an unusual, non-epileptic, cataplexy-like phenomenon in three subjects with the syndrome and we speculate that this feature may go unrecognised. We also provide evidence of neuromuscular dysfunction as part of the phenotype by showing abnormalities on muscle ultrasound in four gene carriers.

Cataplexy↗

Recurrence risks in mental retardation.

Despite improvements in diagnostic techniques and progress made in mapping genes associated with syndromal mental handicap, the estimation of recurrence risks in non-syndromal mental retardation is still dependent on empirical data. Unfortunately, few studies are available to guide the clinician and their results differ significantly. For example, recurrence risks to all sibs of a male index patient with severe mental retardation vary between 3.5% and 14% in commonly quoted series. The present review highlights the problems involved in interpreting the previous work in this area and discusses the definition of mental retardation according to the degree of severity, phenotype, and its pattern of inheritance. In planning future studies, an appreciation of these issues should allow us to derive accurate and comparable risk figures for use in counselling affected subjects and their families.

Female↗

A new strategy for cryptic telomeric translocation screening in patients with idiopathic mental retardation.

Cryptic unbalanced chromosome rearrangements in the telomeric bands of human chromosomes constitute a significant cause of "idiopathic" mental retardation. Here, we have described a new strategy based upon comparative genomic hybridisation (CGH) to screen for these abnormalities. A modified CGH analysis showed three unbalanced cryptic rearrangements in five patients from three families. These chromosome abnormalities and their balanced forms in the relatives were then confirmed by fluorescence in situ hybridisation (FISH). This study describes a new approach to the diagnosis of cryptic translocations between the G band negative ends of chromosomes and confirms the significant contribution of cryptic telomeric rearrangements to idiopathic mental retardation.

Child, Preschool↗

Batten disease in the west of Scotland 1974-1995 including five cases of the juvenile form with granular osmiophilic deposits.

We report on 12 children with neuronal ceroid lipofuscinosis (NCL) diagnosed between 1974-1995 in the West of Scotland. Diagnosis was made on the basis of clinical, electrophysiological, radiological and pathological examination including electron microscopy (EM) in all cases. Incidence was calculated on the basis of the year of diagnosis and the live birth rate. Six cases were infantile and 6 juvenile NCL derived from a total of 10 families. No cases of late infantile or early juvenile NCL were identified. All cases were typical in clinical description. Cumulative incidence was 1.61/100,000 live births (0.87 and 0.73/100,000 live births for juvenile and infantile NCL respectively). There was significant delay in diagnosis of the juvenile form of NCL. EM findings were unusual in the juvenile group in that 5 of 6 cases exhibited granular osmiophilic deposits (GROD) rather than typical fingerprint inclusion bodies. Four of these 5 cases also failed to show vacuolation of lymphocytes. Thus, in the West of Scotland, the distribution of NCL cases by type and by EM findings is unusual, and suggests a distinct genetic variant of juvenile NCL, possibly allelic to infantile NCL.

Age of Onset↗