Genotype and clinical care correlations in craniosynostosis: findings from a cohort of 630 Australian and New Zealand patients.

Craniosynostosis is one of the most common craniofacial disorders encountered in clinical genetics practice, with an overall incidence of 1 in 2,500. Between 30% and 70% of syndromic craniosynostoses are caused by mutations in hotspots in the fibroblast growth factor receptor (FGFR) genes or in the TWIST1 gene with the difference in detection rates likely to be related to different study populations within craniofacial centers. Here we present results from molecular testing of an Australia and New Zealand cohort of 630 individuals with a diagnosis of craniosynostosis. Data were obtained by Sanger sequencing of FGFR1, FGFR2, and FGFR3 hotspot exons and the TWIST1 gene, as well as copy number detection of TWIST1. Of the 630 probands, there were 231 who had one of 80 distinct mutations (36%). Among the 80 mutations, 17 novel sequence variants were detected in three of the four genes screened. In addition to the proband cohort there were 96 individuals who underwent predictive or prenatal testing as part of family studies. Dysmorphic features consistent with the known FGFR1-3/TWIST1-associated syndromes were predictive for mutation detection. We also show a statistically significant association between splice site mutations in FGFR2 and a clinical diagnosis of Pfeiffer syndrome, more severe clinical phenotypes associated with FGFR2 exon 10 versus exon 8 mutations, and more frequent surgical procedures in the presence of a pathogenic mutation. Targeting gene hot spot areas for mutation analysis is a useful strategy to maximize the success of molecular diagnosis for individuals with craniosynostosis.

Novel mutations of the PRKAR1A gene in patients with acrodysostosis.

Acrodysostosis is characterized by a peripheral dysostosis that is accompanied by short stature, midface hypoplasia, and developmental delay. Recently, it was shown that heterozygous point mutations in the PRKAR1A gene cause acrodysostosis with hormone resistance. By mutational analysis of the PRKAR1A gene we detected four different mutations (p.Arg368Stop, p.Ala213Thr, p.Tyr373Cys, and p.Arg335Cys) in four of seven affected patients with acrodysostosis. The combination of clinical results, endocrinological parameters and in silico mutation analysis gives evidence to suppose a pathogenic effect of each mutation. This assumption is supported by the de novo origin of these mutations. Apart from typical radiological abnormalities of the hand bones, elevated thyroid stimulating hormone and parathyroid hormone values as well as short stature are the most common findings. Less frequent features are characteristic facial dysmorphisms, sensorineural hearing loss and mild intellectual disability. These results lead to the conclusion that mutations of PKRAR1A are the major molecular cause for acrodysostosis with endocrinological abnormalities. In addition, in our cohort of 44 patients affected with brachydactyly type E (BDE) we detected only one sequence variant of PRKAR1A (p.Asp227Asn) with an unclear effect on protein function. Thus, we conclude that PRKAR1A mutations may play no major role in the pathogenesis of BDE.

Single bovine sperm sex typing by amelogenin nested PCR.

Sex-sorted bovine semen has become a valuable tool in animal production for sex preselection. Development of novel sperm sexing technologies, or evaluation of the quality of existing methods, often requires a single-sperm, sex-typing method that is reliable and easy to perform. In the present study, we report the development, validation, and application of a simple, reliable, and cost-effective method for single-sperm sex typing using nested polymerase chain reaction (PCR), based on the amelogenin gene. Several hundred single sperm were isolated using a simple manual technique, or a high-speed flow-sorter, and were successfully sex-typed using the amelogenin nested PCR. Based on the pooled results of individual sperm, there was no significant difference in the semen sex ratio of unsorted (44.6% X-sperm and 55.4% Y-sperm) or X/Y-sorted semen (91.4% X-sperm and 94.0% Y-sperm), as compared to the expected ratio in unsorted semen or the post-sorting reanalysis data, respectively. The amelogenin single-sperm sexing method was an adaptable, accurate, and reliable tool for single-sperm sex typing.

Molecular characterisation of SMARCB1 and NF2 in familial and sporadic schwannomatosis.

BACKGROUND: Schwannomatosis is a rare condition characterised by multiple schwannomas and lack of involvement of the vestibular nerve. A recent report identified bi-allelic mutations in the SMARCB1/INI1 gene in a single family with schwannomatosis. We aimed to establish the contribution of the SMARCB1 and the NF2 genes to sporadic and familial schwannomatosis in our cohort. METHODS: We performed DNA sequence and dosage analysis of SMARCB1 and NF2 in 28 sporadic cases and 15 families with schwannomatosis. RESULTS: We identified germline mutations in SMARCB1 in 5 of 15 (33.3%) families with schwannomatosis and 2 of 28 (7.1%) individuals with sporadic schwannomatosis. In all individuals with a germline mutation in SMARCB1 in whom tumour tissue was available, we detected a second hit with loss of SMARCB1. In addition, in all affected individuals with SMARCB1 mutations and available tumour tissue, we detected bi-allelic somatic inactivation of the NF2 gene. SMARCB1 mutations were associated with a higher number of spinal tumours in patients with a positive family history (p = 0.004). CONCLUSION: In contrast to the recent report where no NF2 mutations were identified in a schwannomatosis family with SMARCB1 mutations, in our cohort, a four hit model with mutations in both SMARCB1 and NF2 define a subset of patients with schwannomatosis.

Estimating the referral rate for cancer genetic assessment from a systematic review of the evidence.

To estimate the optimal proportion of new patients diagnosed with cancer who require assessment and evaluation for familial cancer genetic risk, based on the best evidence available. We identified evidence of the patients who require assessment for familial genetic risk when diagnosed with cancer through extensive literature reviews and searches of guidelines. Epidemiological data on the distribution of cancer type, presence of a family history, age and other factors that influence referral for genetic assessment were identified. Decision trees were constructed to merge the evidence-based recommendations with the epidemiological data to calculate the optimal proportion of patients who should be referred. We identified 'high probability' and 'moderate probability' groups for having a genetic susceptibility. The proportion of patients diagnosed with cancer in Australia who have a high probability of having a genetic predisposition and who should be referred for genetic assessment is 1%. If the moderate probability group is also assessed this proportion increases to 6%. This model has identified the proportion of new patients diagnosed with cancer who should be referred for genetic assessment. This data is the first step in determining the resources required for provision of an adequate cancer genetic service.

Histopathology and fibrillin-1 distribution in severe early onset Marfan syndrome.

Marfan syndrome (MFS) is an autosomal dominant condition which may involve the cardiovascular, ocular, skeletal, and other systems. Mutations causing MFS are found in the FBN1 gene, encoding fibrillin-1, an extracellular matrix protein involved in microfibril formation. In the most severe cases, mutations are generally found in exons 24-32, and children with these mutations usually die in the first years of life, of cardiopulmonary failure. We present clinical, molecular and histopathological studies on a patient with severe early onset MFS. He has a mutation in exon 25 of FBN1, a G>A transition at nucleotide position 3131 that converts the codon TGC, coding for cysteine at position 1044, to TAC, coding for tyrosine (C1044Y). This has resulted in abnormalities of the extracellular matrix and a severe clinical phenotype, although he has survived to the age of 14 years.

Kousseff syndrome: a causally heterogeneous disorder.

The existence of Kousseff syndrome as a distinct entity has been thrown into doubt by a recent study conducted on the family originally reported by Kousseff. In all cases where chromosome 22q11.2 FISH testing has been undertaken, including the original sibship, a chromosome 22q11.2-microdeletion has been identified. We report two cases of sacral myelomeningocele associated with a conotruncal cardiac anomaly or "Kousseff syndrome." The first case, a 4-year-old girl, had a sacral myelomeningocele, tetralogy of Fallot, microcephaly, hydrocephalus, hypoplasia of the corpus callosum and mild-moderate developmental delay. Chromosome 22q11.2 FISH was normal and the facial phenotype was not that of velocardiofacial syndrome. Sequencing of the entire coding region of CITED2 did not reveal a mutation. The second case, a male infant, was found to have a 22q11.2-microdeletion. These cases confirm Kousseff syndrome to be a causally heterogeneous disorder.

Principal mutation hotspot for central core disease and related myopathies in the C-terminal transmembrane region of the RYR1 gene.

The congenital myopathies are a group of disorders characterised by the predominance of specific histological features observed in biopsied muscle. Central core disease and nemaline myopathy are examples of congenital myopathies that have specific histological characteristics but significantly overlapping clinical pictures. Central core disease is an autosomal dominant disorder with variable penetrance which has been linked principally to the gene for the skeletal muscle calcium release channel (RYR1). Two recent reports have identified the 3' transmembrane domain of this gene as a common site for mutations. Two other studies have reported single families that have features of both central core disease and nemaline myopathy (core/rod disease) caused by mutations in RYR1. Screening of the 3' region (exons 93-105) of the RYR1 gene for mutations in 27 apparently unrelated patients with either central core disease or core/rod disease by single strand conformation polymorphism analysis and DNA sequencing identified three described and nine novel mutations in 15 patients.

Dhr1p, a putative DEAH-box RNA helicase, is associated with the box C+D snoRNP U3.

Putative RNA helicases are involved in most aspects of gene expression. All previously characterized members of the DEAH-box family of putative RNA helicases are involved in pre-mRNA splicing. Here we report the analysis of two novel DEAH-box RNA helicases, Dhr1p and Dhr2p, that were found to be predominantly nucleolar. Both genes are essential for viability, and MET-regulated alleles were therefore created. Depletion of Dhr1p or Dhr2p had no detectable effect on pre-mRNA splicing in vivo or in vitro. Both Dhr1p and Dhr2p were, however, required for 18S rRNA synthesis. Depletion of Dhr2p inhibited pre-rRNA cleavage at sites A(0), A(1), and A(2), while Dhr1p depletion inhibited cleavage at sites A(1) and A(2). No coprecipitation of snoRNAs was detected with ProtA-Dhr2p, but Dhr1p-ProtA was stably associated with the U3 snoRNA. Depletion of Dhr1p inhibited processing steps that require base pairing of U3 to the 5' end of the 18S rRNA. We speculate that Dhr1p is targeted to the preribosomal particles by the U3-18S rRNA interaction and is required for the structural reorganization of the rRNA during formation of the central pseudoknot.

Genome-wide protein interaction screens reveal functional networks involving Sm-like proteins.

A set of seven structurally related Sm proteins forms the core of the snRNP particles containing the spliceosomal U1, U2, U4 and U5 snRNAs. A search of the genomic sequence of Saccharomyces cerevisiae has identified a number of open reading frames that potentially encode structurally similar proteins termed Lsm (Like Sm) proteins. With the aim of analysing all possible interactions between the Lsm proteins and any protein encoded in the yeast genome, we performed exhaustive and iterative genomic two-hybrid screens, starting with the Lsm proteins as baits. Indeed, extensive interactions amongst eight Lsm proteins were found that suggest the existence of a Lsm complex or complexes. These Lsm interactions apparently involve the conserved Sm domain that also mediates interactions between the Sm proteins. The screens also reveal functionally significant interactions with splicing factors, in particular with Prp4 and Prp24, compatible with genetic studies and with the reported association of Lsm proteins with spliceosomal U6 and U4/U6 particles. In addition, interactions with proteins involved in mRNA turnover, such as Mrt1, Dcp1, Dcp2 and Xrn1, point to roles for Lsm complexes in distinct RNA metabolic processes, that are confirmed in independent functional studies. These results provide compelling evidence that two-hybrid screens yield functionally meaningful information about protein-protein interactions and can suggest functions for uncharacterized proteins, especially when they are performed on a genome-wide scale.

Eosinophilic gastroenteritis presenting as an obstructing cecal mass--a case report and review of the literature.

The causes of colonic obstruction are protean. Less common is the diagnosis of eosinophilic gastroenteritis (EGE). EGE is more common as a cause of more proximal bowel obstruction. To our knowledge, this case represents one of the only reported cases of such a lesion causing obstruction in the cecum.

Patient with a 22q11.2 deletion with no overlap of the minimal DiGeorge syndrome critical region (MDGCR).

The apparent lack of genotype/phenotype correlation in patients with the DiGeorge anomaly and velocardiofacial syndrome (DGA/VCFS; the "22q11 deletion syndrome") indicates a complex genetic condition. Most cases, whatever the phenotype, have a 1.5-3 Mb chromosomal deletion that includes the minimal DiGeorge critical region (MDGCR). Another potential critical region on 22q11 has been suggested based on two patients with distal deletions outside the MDGCR. We report on a patient with a VCFS phenotype who has a deletion, mapped by short tandem repeat polymorphic loci and fluorescence in situ hybridization analysis, distal to and not overlapping the MDGCR. This patient is deleted for several genes, including the T-box 1 gene (TBX1; a transcription regulator expressed early in embryogenesis) and catechol-O-methyltransferase (COMT; involved in neurotransmitter metabolism). We discuss the role these two genes may play in the clinical phenotype of the patient.

Identification of the gene (SEDL) causing X-linked spondyloepiphyseal dysplasia tarda.

Spondyloepiphyseal dysplasia tarda (SEDL; MIM 313400) is an X-linked recessive osteochondrodysplasia that occurs in approximately two of every one million people. This progressive skeletal disorder which manifests in childhood is characterized by disproportionate short stature with short neck and trunk, barrel chest and absence of systemic complications. Distinctive radiological signs are platyspondyly with hump-shaped central and posterior portions, narrow disc spaces, and mild to moderate epiphyseal dysplasia. The latter usually leads to premature secondary osteoarthritis often requiring hip arthroplasty. Obligate female carriers are generally clinically and radiographically indistinguishable from the general population, although some cases have phenotypic changes consistent with expression of the gene defect. The SEDL gene has been localized to Xp22 (refs 8,9) in the approximately 2-Mb interval between DXS16 and DXS987 (ref. 10). Here we confirm and refine this localization to an interval of less than 170 kb by critical recombination events at DXS16 and AFMa124wc1 in two families. In one candidate gene we detected three dinucleotide deletions in three Australian families which effect frameshifts causing premature stop codons. The gene designated SEDL is transcribed as a 2.8-kb transcript in many tissues including fetal cartilage. SEDL encodes a 140 amino acid protein with a putative role in endoplasmic reticulum (ER)-to-Golgi vesicular transport.

Detection of a novel missense mutation and second recurrent mutation in the CACNA1A gene in individuals with EA-2 and FHM.

Mutations in the brain specific P/Q type Ca2+ channel alpha1 subunit gene, CACNA1A, have been identified in three clinically distinct disorders, viz. episodic ataxia type 2 (EA-2), familial hemiplegic migraine (FHM) and spinocerebellar ataxia 6 (SCA6). For individuals with EA-2, the mutations described thus far are presumed to result in a truncated protein product. Several different missense mutations have been identified in patients with FHM. At least two of these mutations have been identified on two different chromosome 19p13 haplotypes and thus represent recurrent mutations. In the present study, we have screened several individuals for mutations in all 47 exons in the CACNA1A gene by single-strand conformation analysis. We have characterised a novel missense mutation, G5260A, in exon 32 in a family segregating for EA-2. The consequence of this mutation is an amino acid substitution at a highly conserved position within the CACNA1A gene. This represents the first point mutation not resulting in a proposed truncated protein. Furthermore, this mutation has been detected in a family member with mild clinical signs including only migraine. Additionally, a second previously identified recurrent muta tion, C2272T, in exon 16 has been discovered in a patient with FHM.

Gene localization for an autosomal dominant familial periodic fever to 12p13.

We report gene localization in a family with a benign autosomal dominant familial periodic fever (FPF) syndrome characterized by recurrent fever associated with abdominal pain. The clinical features are similar to the disorder previously described as familial Hibernian fever, and they differ from familial Mediterranean fever (FMF) in that FPF episodes usually do not respond to colchicine and FPF is not associated with amyloidosis. Frequent recombination with the marker D16S2622, <1 Mb from FMF, at 16p13.3, excluded allelism between these clinically similar conditions. Subsequently, a semiautomated genome search detected linkage of FMF to a cluster of markers at 12p13, with a multipoint LOD score of 6.14 at D12S356. If penetrance of 90% is assumed, the FPF gene maps to a 19-cM interval between D12S314 and D12S364; however, if complete penetrance is assumed, then FPF maps to a 9-cM region between D12S314 and D12S1695. This interval includes the dentatorubropallidoluysian atrophy locus, which, with FPF, gave a maximum two-point LOD score of 3.7 at a recombination fraction of 0. This is the first of the periodic-fever genes, other than FMF, to be mapped. Positional candidate genes may now be selected for mutation analysis to determine the molecular basis for FPF. Together with the recent identification of the defective gene in FMF, identification of a gene for FPF might provide new insights into the regulation of inflammatory responses.

Anal anomalies: an uncommon feature of velocardiofacial (Shprintzen) syndrome?

We report three cases of velocardiofacial syndrome (VCFS) with anal anomalies who have deletions of the 22q11 region and a further case where the proband has VCFS clinically and her father has an anal anomaly. It is important to consider VCFS in the differential diagnosis of children with anal anomalies and to look for other features of the syndrome, such as asymmetrical crying facies, submucous cleft of the palate, developmental delay, cardiac anomalies, and hypoparathyroidism.

Velo-cardio-facial and partial DiGeorge phenotype in a child with interstitial deletion at 10p13--implications for cytogenetics and molecular biology.

We report on a female with a interstitial deletion of 10p13 and a phenotype similar to that seen with the 22q deletion syndromes (DiGeorge/velo-cardio-facial). She had a posterior cleft palate, perimembranous ventricular septal defect, dyscoordinate swallowing, T-cell subset abnormalities, small ears, maxillary and mandibular hypoplasia, broad nasal bridge, deficient alae nasi, contractures of fingers and developmental delay. This could indicate homology of some developmental genes at 22q and 10p so that patients with the velocardiofacial phenotype who do not prove to be deleted on 22q are candidates for a 10p deletion.

Characterisation of four novel fibrillin-1 (FBN1) mutations in Marfan syndrome.

Forty-four percent of the fibrillin-1 gene (FBN1) from 19 unrelated families with Marfan syndrome was screened for putative mutations by single strand conformational polymorphism (SSCP) analysis. Four novel mutations were identified and characterised in five people, three with classical Marfan syndrome (two from one family, and one from an unrelated family), one with a more severe phenotype, and one with neonatal Marfan syndrome. The base substitutions G2113A, G2132A, T3163G, and G3458A result in amino acid substitutions A705T, C711Y, C1055G, and C1152Y, respectively. C711Y, C1055G, and C1152Y lead to replacement of a cysteine by another amino acid; the latter two occur within epidermal growth factor-like motifs in exon 25 and 27, respectively. The A705T mutation occurs at exon 16 adjacent to the GT splice site. The A705T and C711Y mutations, at exon 16 and 17, respectively, are the first documented in the second transforming growth factor-beta 1 binding protein-like motif of FBN1.

Clinical features in 27 patients with Angelman syndrome resulting from DNA deletion.

We report the clinical features in 27 Australasian patients with Angelman syndrome (AS), all with a DNA deletion involving chromosome 15(q11-13), spanning markers from D15S9 to D15S12, about 3 center dot 5 Mb of DNA. There were nine males and 18 females. All cases were sporadic. The mean age at last review (end of 1994) was 11 center dot 2 years (range 3 to 34 years). All patients were ataxic, severely retarded, and lacking recognisable speech. In all patients, head circumference (HC) at birth was normal but skewed in distribution, with 62 center dot 5% at the 10th centile. At last review HC was around the 50th centile in three patients (12 center dot 5%) while 15 had poor postnatal head growth. Short stature was not invariable, 5/26 (19%) were on or above the 50th centile. Hypotonia at birth was recorded in 15/24 (63%) and neonatal feeding difficulties were recorded in 20/26 (77%). Epilepsy was present in 26/27 (96%) with onset by the third year of life in 20 patients (83%). Improvement in epilepsy was reported in 11/16 patients (69%) with age. An abnormal EEG was reported in 25/25 patients. Hypopigmentation was present in 19/26 (73%). One patient had oculocutaneous albinism. Five patients could not walk independently. Of the remaining 22 who could walk, age of onset of walking ranged from 2 to 8 years. Disrupted sleep patterns were present in 18/21 patients (86%), with improvement in 9/12 patients (75%) over 10 years of age. The clinical features in this group of deletional AS patients were similar to previous reports, but these have not separated patients into subgroups based on DNA studies. In our group of deletional cases, 100% showed severe mental retardation, ataxic movements, absent language, abnormal EEG, happy disposition (noted in infancy in 95%), normal birth weight and head circumference at birth, and a large, wide mouth. These features occurred with a higher frequency than in AS patients as a whole. Our study also provided information on the evolution of the phenotype. The data can act as a benchmark for comparisons of AS resulting from other genetic mechanisms.