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Biomedical subjects

Julie McGaughran

Publications and source records attributed to Julie McGaughran.

17 recordsLinked to original sources

Increased yield of genetic diagnoses in inherited heart diseases using expanded genome and RNA-splicing analyses.

PURPOSE: The Australian Genomics Cardiovascular Disorders Flagship investigated genome sequencing as a first-line genetic test in 600 individuals with cardiomyopathy, primary arrhythmia syndromes, or congenital heart disease. Analysis of disease-specific virtual gene panels achieved a genetic diagnosis in 38% of participants. We sought to increase genetic diagnosis yields by analyzing lesser-evidenced disease genes, the mitochondrial genome, and by functional analysis of predicted splice-altering variants. METHODS: Genome sequences of 520 participants with cardiomyopathy or primary arrhythmia syndromes were reanalyzed in 572 cardiac genes and the mitochondrial genome. Participants with congenital heart disease were excluded. Variants predicted in silico to disrupt splicing were assessed with blood RNA and minigenes. RESULTS: A new genetic diagnosis was achieved in 4% (19/520) of participants, including deep intronic and mitochondrial genome variants. Ten participants had diagnostic variants in lesser evidenced disease genes; 9 had splicing variant pathogenicity functionally validated. Eleven participants had a newly identified variant of uncertain significance with high suspicion of pathogenicity, warranting clinical review. Our data supported the gene-disease association of 1 new cardiomyopathy gene, TBX20. CONCLUSION: Identifying new gene-disease relationships, maintaining contemporary gene panels, and integrating functional studies to refine splicing variant classifications increase genetic diagnoses for cardiomyopathies and primary arrhythmia syndromes.

Humans↗

Expanding the spectrum of TBX5 mutations in Holt-Oram syndrome: detection of two intragenic deletions by quantitative real time PCR, and report of eight novel point mutations.

Mutations in the gene TBX5 cause Holt-Oram syndrome (HOS), an autosomal dominant disorder characterized by anterior (i.e., radial ray) upper limb malformations and congenital heart defects and/or cardiac conduction anomalies. The detection rate for TBX5 mutations in HOS patients has been given as 30-35% in most reports. However, a detection rate of 74% was reported when strict clinical inclusion criteria for HOS were applied prior to TBX5 analysis. Still, in a significant proportion of typical HOS cases no mutation can be found within the TBX5 coding region and flanking intronic sequences. One explanation could be that large but submicroscopic deletions of TBX5 could cause HOS, yet only one such TBX5 deletion has been reported to date. We developed a quantitative Real Time PCR strategy to detect large, submicroscopic deletions in TBX5. Using this assay, we screened a total of 102 TBX5 mutation negative patients and discovered two novel intragenic deletions. One deletion of 7756 bp removes exon 6 and a considerable part of the neighboring intronic sequences, and the other of 3695 bp removes exon 9 with the stop codon and the 3'UTR completely as well as a part of the preceding intron 8. We conclude that quantitative Real Time PCR is a reliable method to detect submicroscopic deletions within TBX5. However, such deletions explain only approximately 2% of the TBX5 mutational spectrum in HOS cases. In addition, we also present eight novel TBX5 mutations (three nonsense, one splice mutation, four short deletions) as detected by direct sequencing in 21 families not previously analyzed for mutations.

Arrhythmias, Cardiac↗

A case of Beare-Stevenson syndrome with a broad spectrum of features and a review of the FGFR2 Y375C mutation phenotype.

We present a case of Beare-Stevenson syndrome with a broad range of phenotypic features including craniosynostosis, cutis gyrata, choanal stenosis, bifid scrotum with perineal hypospadias and a caudal appendage. The paternal age at the time of conception was 62 years consistent with a paternal age effect. Mutation analysis was undertaken and demonstrated the FGFR2 Y375C mutation. This case, one of only nine with molecular analysis, confirms the significant morbidity associated with this syndrome.

Abnormalities, Multiple↗

Recurrence of Mowat-Wilson syndrome in siblings with the same proven mutation.

Mowat-Wilson syndrome (MWS) is a mental retardation syndrome associated with distinctive facial features, microcephaly, epilepsy, and a variable spectrum of congenital anomalies, including Hirschsprung disease (HSCR), agenesis of the corpus callosum, genitourinary abnormalities, and congenital heart disease. Heterozygous mutations or deletions involving the gene ZFHX1B (previously SIP1) [OMIM 605802] have recently been found to cause MWS. There have previously been no reports of a sibling recurrence of this syndrome. A brother and sister are described with clinical features of MWS, where both have the same truncating mutation in exon 8 of ZFHX1B. As their parents are phenotypically normal and do not have the mutation in lymphocyte-derived DNA, the most likely explanation is germ-line mosaicism.

Abnormalities, Multiple↗

Mild phenotypes in a series of patients with Opitz GBBB syndrome with MID1 mutations.

Opitz syndrome (OS; MIM 145410 and MIM 300000) is a congenital midline malformation syndrome characterized by hypertelorism, hypospadias, cleft lip/palate, laryngotracheoesophageal (LTE) abnormalities, imperforate anus, developmental delay, and cardiac defects. The X-linked form (XLOS) is caused by mutations in the MID1 gene, which encodes a microtubule-associated RBCC protein. In this study, phenotypic manifestations of patients with and without MID1 mutations were compared to determine genotype-phenotype correlations. We detected 10 novel mutations, 5 in familial cases, 2 in sporadic cases, and 3 in families for whom it was not clear if they were familial or sporadic. The genotype and phenotype was compared for these 10 families, clinically diagnosed OS patients found not to have MID1 mutations, and 4 families in whom we have previously reported MID1 mutations. This combined data set includes clinical and mutation data on 70 patients. The XLOS patients with MID1 mutations were less severely affected than patients with MID1 mutations reported in previous studies, particularly in functionally significant neurologic, LTE, anal, and cardiac abnormalities. Minor anomalies were more prevalent in patients with MID1 mutations compared to those without mutations in this study. Female MID1 mutation carriers had milder phenotypes compared to male MID1 mutation carriers, with the most common manifestation being hypertelorism in both sexes. Most of the anomalies found in the patients of the present study do not correlate with the MID1 mutation type, with the possible exception of LTE malformations. This study demonstrates the wide spectrum of severity and manifestations of OS. It also shows that XLOS patients with MID1 mutations may be less severely affected than indicated in prior reports.

Exons↗

SALL1 mutation analysis in Townes-Brocks syndrome: twelve novel mutations and expansion of the phenotype.

Townes-Brocks syndrome is an autosomal dominantly inherited disorder, which comprises multiple birth defects including renal, ear, anal, and limb malformations. TBS has been shown to result from mutations in SALL1, a human gene related to the developmental regulator SAL of Drosophila melanogaster. The SALL1 gene product is a zinc finger protein thought to act as a transcription factor. It contains four highly conserved, evenly distributed C2H2 double zinc finger domains. A single C2H2 motif is attached to the second domain, and at the amino terminus SALL1 contains a C2HC motif. Most mutations causing TBS are clustered in the N-terminal third of the SALL1 coding region and result in the production of truncated proteins containing only one or none of the C2H2 domains and the N-terminal transcriptional repressor domain of SALL1. Twenty-three SALL1 mutations were reported prior to this work, 22 of which are located in exon 2, 5' of the second double zinc finger-encoding region. Here we present 12 novel mutations in SALL1 associated with Townes-Brocks syndrome in 13 unrelated families. These include three nonsense mutations, three short insertions and six short deletions. Thus the number of SALL1 mutations increases to 35. Rare phenotypical features among mutation positive patients include hypothyroidism, vaginal aplasia with bifid uterus, cryptorchidism, bifid scrotum without hypospadia scrotalis, unilateral chorioretinal coloboma with loss of vision, dorsal hypoplasia of the corpus callosum, and umbilical hernia.

Abnormalities, Multiple↗

Klippel-Feil anomaly in Fanconi anemia.

A boy is described with Fanconi anemia (FA) and Klippel-Feil anomaly. This suggests the diagnosis of FA should be considered in patients with vertebal malformations as well as other suggestive congenital anomalies.

Child↗

Setleis syndrome: three new cases and a review of the literature.

Setleis syndrome is characterized by cutis aplasia or atrophic skin at the temples, which is said to resemble forceps marks. There may also be a coarse facial appearance, anomalies of the eyelashes and eyebrows, and periorbital puffiness. The mouth has a typical appearance with large lips, inverted "V" contour, and downturned overly defined corners. Patients usually have normal intelligence. Here are presented three cases with features of Setleis syndrome. One is an apparently isolated case; the others are father and son. All three have developmental delay. This second family is a further example of autosomal dominant inheritance in Setleis syndrome. These patients also suggest that developmental problems may be a more common manifestation than previously described. Two of the patients are the first described of Pacific Island descent.

Abnormalities, Multiple↗

Complete overlap of PHACE syndrome and sternal malformation--vascular dysplasia association.

PHACE syndrome is the term applied to the association of posterior fossa brain abnormalities, hemangiomas, arterial anomalies in the cranial vasculature, coarctation of the aorta/cardiac defects, and eye abnormalities. An overlap with the sternal malformation/vascular dysplasia association has been described. We report an adult patient with complete manifestations of both conditions. As an adult she has demonstrated resolution of the hemangiomas and only mild intellectual difficulties.

Abnormalities, Multiple↗

Improved clinical management of retinoblastoma through gene testing.

AIMS: To investigate the relative benefits of retinoblastoma gene testing over conventional ophthalmological screening methods in a New Zealand setting, and to determine the importance of tumour material in resolving germline status. METHODS: Three cases of gene testing are described to illustrate the clinical advantages over conventional ophthalmological screening. To determine the role of tumour material in resolving germline status, 24 New Zealand families were tested, of which tumour material was available for eight. RESULTS: In the three cases reported, we found genetic testing of the RB1 gene resulted in clinically significant benefits and cost savings. When fresh tumour was available for high molecular weight DNA extraction, germline status was resolved in 8/8 (100%) cases. In these cases tumour mutations were not present in the corresponding peripheral blood DNA, indicating that the tumours were sporadic. In the absence of tumour DNA, mutations were identified in only 8/13 (62%) heritable cases. Germline status remains unresolved in all of the three cases of unilateral tumour without a family history or tumour DNA. CONCLUSIONS: Our experience indicates that retinoblastoma gene testing has significant benefits to the affected individuals and their families in New Zealand. Moreover, DNA extracted from fresh tumour allows retinoblastoma germline status in most cases to be defined. Without rumour material, the germline status of potentially sporadic cases will remain undetermined since the absence of detectable RB1 coding region mutations does not exclude all possible mutations in the RB1 gene, which is too large for DNA analysis. A lack of conclusive results will mean that infants will be subjected to the unnecessary inconvenience of surveillance under general anaesthesia.

Cost Savings↗

Prenatal diagnosis of partial tetrasomy 14: a case study.

Prenatal specimens were received from a fetus with abnormalities noted on ultrasound. A supernumerary marker chromosome (SMC) was detected: 47,XY,+mar. Fluorescence in situ hybridisation (FISH) further classified this to be partial tetrasomy for chromosome 14. We compare this finding with other cases of SMC (14) and further classify phenotype with karyotype.

Adult↗

A severe case of oculo-ectodermal syndrome?

We describe a child with features of the oculo-ectodermal syndrome, who in addition to the cardinal manifestations of cutis aplasia and epibulbar dermoid had a number of other features. These include laryngomalacia, an anterior anus, microcephaly and significant developmental delay. The parents are of New Zealand Maori ancestry and are related as half first cousins, raising the possibility that this syndrome may be recessively inherited.

Abnormalities, Multiple↗

Prenatal diagnosis of mosaic trisomy 20 in New Zealand.

OBJECTIVE: Mosaic trisomy 20 is not an uncommon finding on amniocentesis or CVS. Unlike other mosaic aneuploidies it is a relatively benign abnormality which, along with a lack of long-term follow-up of cases, has led to uncertainty when counselling parents. We aimed to identify known mosaic trisomy 20 pregnancies in New Zealand in the last 10 years and document their outcome. DESIGN: Retrospective database review with prospective clinical follow-up. METHODS: Cases were identified from the databases of the two clinical genetic services, as well as the four regional cytogenetics laboratories. Medical records were reviewed and where patients were available they were offered follow-up. RESULTS: Fourteen cases were identified (13 on amniocentesis, one on CVS), all with low levels of mosaicism (8-50%). In 12 cases, the children were physically and developmentally normal, with the longest follow-up being 10 years. Minor anomalies were noted in two cases. There were no major malformations noted in any of the cases and where repeat karyotypes were performed on blood or urine cytology these were normal. CONCLUSIONS: This series confirms a much lower incidence of phenotypic abnormalities associated with mosaic trisomy 20 compared to other forms of mosaic aneuploidy. Attempts to predict which of these pregnancies will have poor outcomes have not proven to be reliable. We recommend that, if a detailed anatomy scan is normal, parents be counselled that the risk of abnormality is less than 10%. Further tests should be performed only on the basis of a clinical indication.

Adult↗