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.

Effect of mutation type and location on clinical outcome in 1,013 probands with Marfan syndrome or related phenotypes and FBN1 mutations: an international study.

Mutations in the fibrillin-1 (FBN1) gene cause Marfan syndrome (MFS) and have been associated with a wide range of overlapping phenotypes. Clinical care is complicated by variable age at onset and the wide range of severity of aortic features. The factors that modulate phenotypical severity, both among and within families, remain to be determined. The availability of international FBN1 mutation Universal Mutation Database (UMD-FBN1) has allowed us to perform the largest collaborative study ever reported, to investigate the correlation between the FBN1 genotype and the nature and severity of the clinical phenotype. A range of qualitative and quantitative clinical parameters (skeletal, cardiovascular, ophthalmologic, skin, pulmonary, and dural) was compared for different classes of mutation (types and locations) in 1,013 probands with a pathogenic FBN1 mutation. A higher probability of ectopia lentis was found for patients with a missense mutation substituting or producing a cysteine, when compared with other missense mutations. Patients with an FBN1 premature termination codon had a more severe skeletal and skin phenotype than did patients with an inframe mutation. Mutations in exons 24-32 were associated with a more severe and complete phenotype, including younger age at diagnosis of type I fibrillinopathy and higher probability of developing ectopia lentis, ascending aortic dilatation, aortic surgery, mitral valve abnormalities, scoliosis, and shorter survival; the majority of these results were replicated even when cases of neonatal MFS were excluded. These correlations, found between different mutation types and clinical manifestations, might be explained by different underlying genetic mechanisms (dominant negative versus haploinsufficiency) and by consideration of the two main physiological functions of fibrillin-1 (structural versus mediator of TGF beta signalling). Exon 24-32 mutations define a high-risk group for cardiac manifestations associated with severe prognosis at all ages.

FBN1, TGFBR1, and the Marfan-craniosynostosis/mental retardation disorders revisited.

The recent identification of TGFBR2 mutations in Marfan syndrome II (MFSII) [Mizuguchi et al. (2004); Nat Genet 36:855-860] and of TGFBR1 and TGFBR2 mutations in Loeys-Dietz aortic aneurysm syndrome (LDS) [Loeys et al. (2005); Nat Genet 37:275-281] [OMIM 609192] has provided direct evidence of abnormal signaling in transforming growth factors beta (TGF-beta) in the pathogenesis of Marfan syndrome (MFS). In light of this, we describe the phenotypes and genotypes of five individuals. Patient 1 had MFS and abnormal cranial dura. Patient 2 had severe early onset MFS and an abnormal skull. Patients 3 and 4 had probable Furlong syndrome (FS). Patient 5 had marfanoid (MD) features, mental retardation (MR), and a deletion of chromosome 15q21.1q21.3. All patients had a condition within the MFS, MD-craniosynostosis (CS) or MD-MR spectrum. The names of these entities may become redundant, and instead, come to be considered within the spectrum of TGF-beta signaling pathway disorders. Two recurrent heterozygous FBN1 mutations were found in Patients 1 and 2, and an identical novel heterozygous de novo TGFBR1 mutation was found in Patients 3 and 4, in whom altered fibrillin-1 processing was demonstrated previously [Milewicz et al. (2000); Am J Hum Genet 67:279]. A heterozygous FBN1 deletion was found in Patient 5. These findings support the notion that perturbation of extracellular matrix homeostasis and/or remodeling caused by abnormal TGF-beta signaling is the core pathogenetic mechanism in MFS and related entities including the MD-CS syndromes.

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.

Severe spontaneous intracranial hypotension and Marfan syndrome in an adolescent.

We describe a 14-year-old girl with Marfan syndrome who presented with severe postural headache. Dural ectasia was demonstrated radiologically. Cerebrospinal fluid (CSF) pressure was immeasurable on formal measurement. Radionucleide cisternography failed to demonstrate a CSF leak. We consider that the underlying fibrillinopathy in Marfan syndrome rendered the dura sufficiently permeable to CSF leakage to cause the low CSF pressure headache. The patient was treated successfully with epidural autologous blood patch.

PEHO and PEHO-like syndromes: report of five Australian cases.

PEHO syndrome is a rare progressive infantile encephalopathy with onset within the first few months of life. Few patients fulfilling the diagnostic criteria for PEHO syndrome have been reported outside Finland. Affected infants have facial dysmorphism and suffer from severe hypotonia, profound mental retardation, convulsions (often with a hypsarrhythmic EEG pattern), transient or persistent peripheral oedema, and optic atrophy. Cerebellar and brainstem atrophy are usually present on neuroimaging. A PEHO-like syndrome has been described, in which the affected individuals have neither optic atrophy nor the typical neuroradiological findings. We report five Australian patients, the first with classical features of PEHO syndrome, and four who have a PEHO-like disorder. We compare their features with other published cases. We suggest that PEHO or a PEHO-like syndrome may affect more patients than are currently identified, based on the original diagnostic criteria for this disorder.

Two further cases of Ohdo syndrome delineate the phenotypic variability of the condition.

Ohdo syndrome (MIM 249620) is a multiple malformation syndrome characterized by blepharophimosis, ptosis, dental hypoplasia, hearing impairment and intellectual disability. A wide range of dysmorphic features and congenital abnormalities have been described in cases reported as Ohdo and Ohdo-like syndromes. We report a further two cases of Ohdo syndrome, one with mild features and the other more severely affected, illustrating the phenotypic variability of the condition. A review of the literature highlights the severe phenotype associated with distinctive facial features, as seen in Case 2 in this report All cases with the severe phenotype have been sporadic. Subtelomeric FISH studies of all chromosome arms on the two cases showed no abnormality. We propose clinical criteria for the diagnosis of Ohdo syndrome and delineate features of the severe phenotype.

A variant microcephalic osteodysplastic slender-bone disorder with growth hormone deficiency and a pigmentary retinopathy.

We present the case of a 3-year-old boy with post-natal growth failure, microcephaly, developmental delay, facial dysmorphism, an evolving pigmentary retinopathy, pituitary hypoplasia, micropenis, and growth hormone (GH) deficiency. He has a microcephalic osteodysplastic slender-bone disorder with disharmonic delayed osseous maturation, most closely resembling patients with microcephalic osteodysplastic primordial dwarfism type II (MOPD II). Intrauterine growth retardation, a universal finding in the MOPD II, was absent in our patient.

Macrocephaly--cutis marmorata telangiectatica congenita: report of five patients and a review of the literature.

Cutis marmorata telangiectatica congenita (CMTC) is a cutaneous disorder often accompanied by additional anomalies, most commonly segmental overgrowth. Recently a clinically discrete condition has been described comprising CMTC and congenital macrocephaly together with pre- and post-natal macrosomia, segmental overgrowth, central nervous system malformations, connective tissue abnormalities and intellectual handicap. We describe the natural history of macrocephaly-CMTC (M-CMTC) syndrome in a further five patients including the oldest reported patient, a 22 year old. The addition of our five patients brings the total number of reported patients to 28 and now makes it possible to more accurately delineate the phenotype and the frequency of clinical manifestations. We add some further clinical associations to those previously described, including anomalies of the growth of hair and teeth, neuronal migration defects, dislocated hips and stridor. We discuss potential genetic mechanisms that might account for the pleiotropic manifestations of this apparently rare segmental overgrowth disorder.

Aortic dissection, patent ductus arteriosus, iris hypoplasia and brachytelephalangy in a male adolescent.

We describe a 14-year-old male with dissection of the descending aorta, bilateral iris hypoplasia, striae distensae and brachytelephalangy, the latter being most marked in the thumbs. Inguinal herniae and a patent ductus arteriosus were surgically repaired in infancy. The pattern of abnormalities may constitute a previously undescribed syndrome. The proband died suddenly at the age of 17 years.

Severe micrognathia, cleft palate, absent olfactory tract, and abnormal rib development: cerebro-costo-mandibular syndrome or a new syndrome?

We report on a family in which two sibs had apparently absent ribs and severe micrognathia on prenatal ultrasonography. The pregnancies were terminated at 19 and 12 weeks of gestation, respectively. Autopsy findings in the first fetus (19 weeks of gestation) included severe micrognathia, a U-shaped defect of the soft palate, marked postnuchal edema, absent olfactory bulbs, and cribriform plate and rib abnormalities. The ribs consisted of cartilage anteriorly, with only a small amount of fibrous tissue present laterally and posteriorly. The second fetus (12 weeks gestation) had agnathia, with a large U-shaped defect in the soft palate. There was moderate postnuchal edema. The ribs were unossified and there were gaps in the cartilage where primitive mesenchyme was present posteriorly and laterally. These findings are consistent with a severe form of cerebro-costo-mandibular syndrome. The early fetal histopathology of both cases suggests a possible mechanism by which the characteristic "rib gaps" of cerebro-costo-mandibular syndrome may develop, with evidence for abnormal function of a gene or genes involved in regulation of rib chondrogenesis.

Preferential pre-mRNA utilisation of an upstream cryptic 5' splice site created by a single base deletion mutation in exon 37 of the FBN-1 gene.

A heterozygous deletion of a single base (A4704) from exon 37 of the fibrillin-1 gene was defined in a patient with Marfan syndrome and subsequently in his previously undiagnosed father. The deletion created a cryptic 5' splice site in exon 37 which was utilised in preference to the normal 5' splice site during pre-mRNA processing in skin fibroblasts cultured from the proband. The mutant mRNA showed a 48-bp deletion from the 3' end of exon 37 which was predicted to restore the reading frame in the mutant mRNA and result in the deletion of a 16-amino-acid sequence from a central eight-cysteine repeat motif of the fibrillin-1 molecule. Interestingly, the cryptic 5' splice site in exon 37 and the normal 5' splice site had equally strong consensuses for splice-site selection. The preferential utilisation of the cryptic site is discussed in relation to current theories on the mechanisms involved in pre-mRNA splicing. Analysis by reverse-transcription PCR indicated that, in the patients skin fibroblasts, the steady-state level of the mis-spliced mutant mRNA was close to that from the normal allele. In addition, evidence from immunoblotting and pulse-chase biosynthetic labelling indicated that close to normal amounts of fibrillin-1 were being synthesised and secreted by the cells. However, in contrast to control cells cultured from an unaffected individual, little fibrillin-1 was detected, either biosynthetically or by immunofluorescence, in the extracellular matrix produced by the proband's fibroblasts. Thus, the slightly shorter mutant fibrillin-1 molecules appeared to be exerting a powerful dominant-negative effect on the incorporation of normal fibrillin-1 molecules into microfibrils in this culture system. This severe inhibition of microfibril synthesis in cell culture contrasts with the 'classic' phenotype of the proband, suggesting that factors influencing microfibril formation may differ greatly between in vivo and in vitro environments.

Hirschsprung disease, microcephaly, mental retardation, and characteristic facial features: delineation of a new syndrome and identification of a locus at chromosome 2q22-q23.

We have identified six children with a distinctive facial phenotype in association with mental retardation (MR), microcephaly, and short stature, four of whom presented with Hirschsprung (HSCR) disease in the neonatal period. HSCR was diagnosed in a further child at the age of 3 years after investigation for severe chronic constipation and another child, identified as sharing the same facial phenotype, had chronic constipation, but did not have HSCR. One of our patients has an interstitial deletion of chromosome 2, del(2)(q21q23). These children strongly resemble the patient reported by Lurie et al with HSCR and dysmorphic features associated with del(2)(q22q23). All patients have been isolated cases, suggesting a contiguous gene syndrome or a dominant single gene disorder involving a locus for HSCR located at 2q22-q23. Review of published reports suggests that there is significant phenotypic and genetic heterogeneity within the group of patients with HSCR, MR, and microcephaly. In particular, our patients appear to have a separate disorder from Goldberg-Shprintzen syndrome, for which autosomal recessive inheritance has been proposed because of sib recurrence and consanguinity in some families.

A unique point mutation in the fibroblast growth factor receptor 3 gene (FGFR3) defines a new craniosynostosis syndrome.

The underlying basis of many forms of syndromic craniosynostosis has been defined on a molecular level. However, many patients with familial or sporadic craniosynostosis do not have the classical findings of those craniosynostosis syndromes. Here we present 61 individuals from 20 unrelated families where coronal synostosis is due to an amino acid substitution (Pro250Arg) that results from a single point mutation in the fibroblast growth factor receptor 3 gene on chromosome 4p. In this instance, a new clinical syndrome is being defined on the basis of the molecular finding. In addition to the skull findings, some patients had abnormalities on radiographs of hands and feet, including thimble-like middle phalanges, coned epiphyses, and carpal and tarsal fusions. Brachydactyly was seen in some cases; none had clinically significant syndactyly or deviation of the great toe. Sensorineural hearing loss was present in some, and developmental delay was seen in a minority. While the radiological findings of hands and feet can be very helpful in diagnosing this syndrome, it is not in all cases clearly distinguishable on a clinical basis from other craniosynostosis syndromes. Therefore, this mutation should be tested for in patients with coronal synostosis.

Clinicopathologic findings in congenital aneurysms of the great vessels.

We describe the clinical, histopathologic, and angiographic findings in four children with congenital abnormalities of the great vessels of unknown cause, comprising either single or multiple arterial aneurysms, aortic/arterial dilatation, vessel tortuosity, or combinations of these abnormalities. Two children had early and severe respiratory distress due to aneurysmal compression of the trachea. All children had diffuse dilatation of several arteries, and two children also had tortuosity of multiple arteries. Progression of these abnormalities was clearly evident in one child, in whom diffuse vessel irregularity and tortuosity affected intra-abdominal, and intra and extra-cranial arteries. One child died at 5 years, while the other three have undergone successful surgical repair in the first 3 months of life and are now well, between age 2.5 and 7 years. The phenotype of each child appears unique but all have in common the rare finding of aneurysms of the aorta and main pulmonary artery. Congenital aortic aneurysms did not occur as an isolated finding in any of these children.

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.

Myocardial infarction resulting from coronary artery dissection in an adolescent with Ehlers-Danlos syndrome type IV due to a type III collagen mutation.

Ehlers-Danlos syndrome encompasses a group of inherited disorders of connective tissue, some of which are characterised by abnormalities of collagen metabolism. The chromosomal location, identified genes and biochemical defects, inheritance pattern, and clinical features for the various known subtypes are outlined. Prenatal diagnosis is possible for types IV, VI, VIIA1, and VIIA2. An unusual presentation of type IV Ehlers-Danlos syndrome in a 16 year old boy with an anterior myocardial infarction resulting from dissection of the left anterior descending coronary artery is reported here. A clinical diagnosis of type IV Ehlers-Danlos syndrome was made subsequently and confirmed by the reduced production, impaired secretion, and abnormally slow electrophoretic migration of type III collagen, indicating an underlying mutation in the COL3A1 gene. This patient represents the first case of type IV Ehlers-Danlos syndrome with symptomatic coronary artery dissection.

Distinct skeletal abnormalities in four girls with Shprintzen-Goldberg syndrome.

We describe 4 girls with Shprintzen-Goldberg syndrome. Skeletal abnormalities common to 3 of them include bowing of long bones (with a variable degree of progression over time), flare of the metaphyses, a large anterior fontanel with persistent patency into the second to fourth years of life, 13 pairs of ribs, distinct vertebral abnormalities which were absent neonatally but evolved by the second year of life, and progressive osteopenia. These abnormalities were generalized and, in one case, progressive over the first few years of life. Communicating hydrocephalus was present in all 4 cases. The eldest, an 11-year-old girl, had additional anomalies not reported previously in this syndrome, including intestinal malrotation, an anteriorly placed anus, and mild cerebral atrophy. This is the first detailed report of skeletal manifestations in this rare disorder of unknown cause. These cases, in conjunction with a review of the literature, suggest that skeletal abnormalities are common in Shprintzen-Goldberg syndrome.