Clinical and genetic aspects of trigonocephaly: a study of 25 cases

We reviewed 25 patients ascertained through the finding of trigonocephaly/metopic synostosis as a prominent manifestation. In 16 patients, trigonocephaly/metopic synostosis was the only significant finding (64%); 2 patients had metopic/sagittal synostosis (8%) and in 7 patients the trigonocephaly was part of a syndrome (28%). Among the nonsyndromic cases, 12 were males and 6 were females and the sex ratio was 2 M:1 F. Only one patient with isolated trigonocephaly had an affected parent (5.6%). All nonsyndromic patients had normal psychomotor development. In 2 patients with isolated metopic/sagittal synostosis, FGFR2 and FGFR3 mutations were studied and none were detected. Among the syndromic cases, two had Jacobsen syndrome associated with deletion of chromosome 11q 23 (28.5%). Of the remaining five syndromic cases, different conditions were found including Say-Meyer syndrome, multiple congenital anomalies and bilateral retinoblastoma with no detectable deletion in chromosome 13q14.2 by G-banding chromosomal analysis and FISH, I-cell disease, a new acrocraniofacial dysostosis syndrome, and Opitz C trigonocephaly syndrome. The last two patients were studied for cryptic chromosomal rearrangements, with SKY and subtelomeric FISH probes. Also FGFR2 and FGFR3 mutations were studied in two syndromic cases, but none were found. This study demonstrates that the majority of cases with nonsyndromic trigonocephaly are sporadic and benign, apart from the associated cosmetic implications. Syndromic trigonocephaly cases are causally heterogeneous and associated with chromosomal as well as single gene disorders. An investigation to delineate the underlying cause of trigonocephaly is indicated because of its important implications on medical management for the patient and the reproductive plans for the family.     

Syndromal and nonsyndromal primary trigonocephaly: Analysis of a series of 237 patients

From a series of 1,713 patients with craniosynostosis hospitalized between 1976 and 1996, 237 propositi with metopic synostosis were analyzed. The prevalence of metopic synostosis was estimated in the order of 1 in 15,000 children. Family information was obtained from 184 propositi from 179 families. The male-to-female ratio was 3.3:1. There was no maternal or paternal age effect. A family history was obtained in 10 of the 179 families, giving a 5.6% figure of familial cases. The frequency of twinning was 7.8% with two concordances for metopic synostosis in two monozygotic twin pairs. The male-to-female ratio, the twinning frequency, and the proportion of familial cases in trigonocephaly are very similar to those observed in scaphocephaly, which also involves the longitudinal sutural system. Fetal exposure to valproic acid was noticed in eight cases. The series was divided into two groups: nonsyndromal trigonocephaly (n = 184) and trigonocephaly associated with other malformations (n = 53). The second group included 13 cases of well-delineated syndromes and 40 cases of trigonocephaly associated with one or more malformations, but without any known syndrome, that could be undelineated syndromes. These groups differed significantly in their mental prognosis. Am. J. Med. Genet. 75:211–215, 1998. © 1998 Wiley-Liss, Inc.     

Trigonocephaly in a boy with paternally inherited deletion 22q11.2 syndrome

Deletion 22q11.2 syndrome is a well-known contiguous gene syndrome, for which the list of findings is extensive and varies from patient to patient. We encountered a unique patient who had a familial 3-Mb deletion 22q11.2 associated with trigonocephaly derived from craniosynostosis of the metopic suture. Almost all the symptoms of the patient, including polymicrogyria, microcephaly, facial abnormalities, internal anomalies, seizures, and mental retardation, were compatible with deletion 22q11.2 syndrome, except for synostosis of the metopic suture. This is the first report of a relationship between deletion 22q11.2 syndrome and trigonocephaly. Craniosynostosis of the metopic suture might be a minor complication of deletion 22q11.2, although coincidental occurrence cannot be ruled out.     

Clinical and molecular delineation of the Greig cephalopolysyndactyly contiguous gene deletion syndrome and its distinction from acrocallosal syndrome

Greig cephalopolysyndactyly syndrome (GCPS) is caused by haploinsufficiency of GLI3 on 7p13. Features of GCPS include polydactyly, macrocephaly, and hypertelorism, and may be associated with cognitive deficits and abnormalities of the corpus callosum. GLI3 mutations in GCPS patients include point, frameshift, translocation, and gross deletion mutations. FISH and STRP analyses were applied to 34 patients with characteristics of GCPS. Deletions were identified in 11 patients and the extent of their deletion was determined. Nine patients with deletions had mental retardation (MR) or developmental delay (DD) and were classified as severe GCPS. These severe GCPS patients have manifestations that overlap with the acrocallosal syndrome (ACLS). The deletion breakpoints were analyzed in six patients whose deletions ranged in size from 151 kb to 10.6 Mb. Junction fragments were found to be distinct with no common sequences flanking the breakpoints. We conclude that patients with GCPS caused by large deletions that include GLI3 are likely to have cognitive deficits, and we hypothesize that this severe GCPS phenotype is caused by deletion of contiguous genes.     

New insights into genotype–phenotype correlation for GLI3 mutations

The phenotypic spectrum of GLI3 mutations includes autosomal dominant Greig cephalopolysyndactyly syndrome (GCPS) and Pallister–Hall syndrome (PHS). PHS was first described as a lethal condition associating hypothalamic hamartoma, postaxial or central polydactyly, anal atresia and bifid epiglottis. Typical GCPS combines polysyndactyly of hands and feet and craniofacial features. Genotype–phenotype correlations have been found both for the location and the nature of GLI3 mutations, highlighting the bifunctional nature of GLI3 during development. Here we report on the molecular and clinical study of 76 cases from 55 families with either a GLI3 mutation (49 GCPS and 21 PHS), or a large deletion encompassing the GLI3 gene (6 GCPS cases). Most of mutations are novel and consistent with the previously reported genotype–phenotype correlation. Our results also show a correlation between the location of the mutation and abnormal corpus callosum observed in some patients with GCPS. Fetal PHS observations emphasize on the possible lethality of GLI3 mutations and extend the phenotypic spectrum of malformations such as agnathia and reductional limbs defects. GLI3 expression studied by in situ hybridization during human development confirms its early expression in target tissues.     

Point mutations in human GLI3 cause Greig syndrome

Greig cephalopolysyndactyly syndrome (GCPS, MIM 175700) is a rare autosomal dominant developmental disorder characterized by craniofacial abnormalities and post-axial and pre-axial polydactyly as well as syndactyly of hands and feet. Human GLI3, located on chromosome 7p13, is a candidate gene for the syndrome because it is interrupted by translocation breakpoints associated with GCPS. Since hemizygosity of 7p13 resulting in complete loss of one copy of GLI3 causes GCPS as well, haploinsufficiency of this gene was implicated as a mechanism to cause this developmental malformation. To determine if point mutations within GLI3 could be responsible for GCPS we describe the genomic sequences at the boundaries of the 15 exons and primer pair sequences for mutation analysis with polymerase chain reaction-based assays of the entire GLI3 coding sequences. In two GCPS cases, both of which did not exhibit obvious cytogenetic rearrangements, point mutations were identified in different domains of the protein, showing for the first time that Greig syndrome can be caused by GLI3 point mutations. In one case a nonsense mutation in exon X generates a stop codon truncating the protein in the C-H link of the first zinc finger. In the second case a missense mutation in exon XIV causes a Pro-->Ser replacement at a position that is conserved among GLI genes from several species altering a potential phosphorylation site.      

Zoom-in comparative genomic hybridisation arrays for the characterisation of variable breakpoint contiguous gene syndromes

Contiguous gene syndromes cause disorders via haploinsufficiency for adjacent genes. Some contiguous gene syndromes (CGS) have stereotypical breakpoints, but others have variable breakpoints. In CGS that have variable breakpoints, the extent of the deletions may be correlated with severity. The Greig cephalopolysyndactyly contiguous gene syndrome (GCPS-CGS) is a multiple malformation syndrome caused by haploinsufficiency of GLI3 and adjacent genes. In addition, non-CGS GCPS can be caused by deletions or duplications in GLI3. Although fluorescence in situ hybridisation (FISH) can identify large deletion mutations in patients with GCPS or GCPS-CGS, it is not practical for identification of small intragenic deletions or insertions, and it is difficult to accurately characterise the extent of the large deletions using this technique. We have designed a custom comparative genomic hybridisation (CGH) array that allows identification of deletions and duplications at kilobase resolution in the vicinity of GLI3. The array averages one probe every 730 bp for a total of about 14,000 probes over 10 Mb. We have analysed 16 individuals with known or suspected deletions or duplications. In 15 of 16 individuals (14 deletions and 1 duplication), the array confirmed the prior results. In the remaining patient, the normal CGH array result was correct, and the prior assessment was a false positive quantitative polymerase chain reaction result. We conclude that high-density CGH array analysis is more sensitive than FISH analysis for detecting deletions and provides clinically useful results on the extent of the deletion. We suggest that high-density CGH array analysis should replace FISH analysis for assessment of deletions and duplications in patients with contiguous gene syndromes caused by variable deletions.     

Changing phenotype in Floating-Harbor syndrome

We report on a girl with Floating-Harbor syndrome, trigonocephaly due to metopic suture synostosis, preauricular pit, hypoplastic thumb, subluxated radial head, and Sprengel deformity. A review suggests that trigonocephaly may be an important craniofacial manifestation in this syndrome that is recognizable in infancy. With time, this finding appears to become less noticeable, and the face develops a triangular shape, accentuated by a broad and bulbous nose. Am. J. Med. Genet. 76:58–61, 1998. © 1998 Wiley-Liss, Inc.     

The final demise of Rodriguez lethal acrofacial dysostosis: A case report and review of the literature

We evaluated a newborn with acrofacial dysostosis in whom a clinical diagnosis of Nager syndrome was entertained. Radiographs revealed hypoplasia of the scapulae and bilateral humeroradial synostosis, with absent ulna on the left and hypoplastic ulna on the right. The finding of bilateral humeroradial synostosis had not been seen in cases of Nager syndrome before and we considered other diagnoses. Humeroradial synostosis has been found in three cases of acrofacial dysostosis Rodriguez type, a syndrome characterized by mandibular hypoplasia, upper and lower extremity phocomelia, and oligodactyly of the upper limbs. More recently, haploinsufficiency of the SF3B4 gene has been identified as the cause of both Nager and Rodriguez syndrome, leading many to believe that Rodriguez syndrome represents a more severe end of a Nager syndrome spectrum. An SF3B4 mutation was found in our patient, prompting a review of the previous known cases of Rodriguez syndrome, which revealed no clustering of SF3B4 mutations, and four cases of Rodriguez syndrome with mutations identical to those in cases of Nager syndrome. Rodriguez syndrome was previously thought of as a lethal acrofacial dysostosis distinct from Nager syndrome. A number of more mild cases, as well as our case, intermediate between the two phenotypes, illustrate that Rodriguez syndrome is a severe manifestation of Nager syndrome, and is not lethal with aggressive medical care.     

The clinical spectrum of complete FBN1 allele deletions

The most common mutations found in FBN1 are missense mutations (56%), mainly substituting or creating a cysteine in a cbEGF domain. Other mutations are frameshift, splice and nonsense mutations. There are only a few reports of patients with marfanoid features and a molecularly proven complete deletion of a FBN1 allele. We describe the clinical features of 10 patients with a complete FBN1 gene deletion. Seven patients fulfilled the Ghent criteria for Marfan syndrome (MFS). The other three patients were examined at a young age and did not (yet) present the full clinical picture of MFS yet. Ectopia lentis was present in at least two patients. Aortic root dilatation was present in 6 of the 10 patients. In three patients, the aortic root diameter was on the 95th percentile and in one patient, the diameter of the aortic root was normal, the cross-section, however, had a cloverleaf appearance. Two patients underwent aortic root surgery at a relatively young age (27 and 34 years). Mitral valve prolapse was present in 4 of the 10 patients, and billowing of the mitral valve in 1. All patients had facial and skeletal features of MFS. Two patients with a large deletion extending beyond the FBN1 gene had an extended phenotype. We conclude that complete loss of one FBN1 allele does not predict a mild phenotype, and these findings support the hypothesis that true haploinsufficiency can lead to the classical phenotype of Marfan syndrome.     

A girl with metopic synostosis and trisomy 13 mosaicism: case report and review of the literature

Trisomy 13, or Patau syndrome is a rare chromosomal disorder characterized by a triad of cleft lip and palate, postaxial polydactyly and microcephaly. Complete, partial, or mosaic forms of the disorder can occur. Mosaic trisomy 13 is very rare, it occurs in only 5% of all patients with trisomy 13 phenotype. Metopic synostosis (MS) is premature fusion of the metopic suture, which is part of the frontal suture. It results in a V-shaped abnormality at the front of the skull. MS may occur in a syndromic or nonsyndromic form. We report on a 24-day-old girl with hypotonia, MS, trigonocephaly, capillary hemangioma, hypotelorism, upward slanting palpebral fissures, epicanthal folds, small nose with anteverted nares, high palate, ankyloglossia, long philtrum, low-set ears, short neck, postaxial polydactyly of both hands and feet and congenital heart defect. Cytogenetic analysis demonstrated trisomy 13 mosaicism; 46,XX[58]/47,XX,+13[42]. Although MS has been previously reported in complete and partial forms of trisomy 13, it has not been reported in mosaic form of trisomy 13. Our report supports the evidence that trisomy 13 causes MS. It also emphasizes the need for cytogenetic investigations in patients presenting with MS and multiple congenital anomalies for providing accurate diagnosis, genetic counseling, and prenatal diagnosis.     

The clinical atlas of Greig cephalopolysyndactyly syndrome

Greig cephalopolysyndactyly syndrome (GCPS) is a rare multiple congenital anomaly syndrome that is inherited in an autosomal dominant pattern and is caused by haploinsufficiency of the GLI3 gene. The syndrome typically includes preaxial or mixed pre- and postaxial polydactyly and cutaneous syndactyly, ocular hypertelorism, and macrocephaly in its typical forms, but sometimes includes hydrocephalus, seizures, mental retardation, and developmental delay in more severe cases. Patients with milder forms of GCPS can have subtle craniofacial dysmorphic features that are difficult to distinguish from normal variation. This article presents the spectrum of dysmorphic findings in GCPS highlighting some of its key presenting features to familiarize clinicians with the variable expressivity of the condition.     

Probable Opitz trigonocephaly C syndrome with medulloblastoma

We report on a patient with trigonocephaly, biparietal widening as a result of metopic synostosis, strabismus, upslanted palpebral fissures, apparently low-set ears with abnormal helices, deeply furrowed palate, postaxial polysyndactyly of the feet, ankle flexion deformities, cryptorchidism, loose skin, and severe mental retardation, findings compatible with a diagnosis of the Opitz trigonocephaly C syndrome (OTS). At the age of 12 years this patient presented with symptoms of raised intracranial pressure. A biopsy showed findings diagnostic of a medulloblastoma WHO Grade IV, an unprecedented finding in OTS. The possibility of coincidence should not prevent continued surveillance of OTS patients in the future for the occurrence of malignancy. Am. J. Med. Genet. 69:395–399, 1997. © 1997 Wiley-Liss, Inc.     

Greig cephalopolysyndactyly syndrome: altered phenotype of a microdeletion syndrome due to the presence of a cytogenetic abnormality

A male had several features of Greig cephalopolysyndactyly syndrome (GCPS) and significant developmental delay. He was found to have a de novo chromosomal deletion of chromosome no. 7 involving p13; this resulted in loss of the zinc finger gene, GLI3, which is the candidate gene in this syndrome. Modification of the CGPS phenotype in a sporadic case emphasizes the importance of searching for a chromosomal origin of this autosomal dominant disorder. Detection of a chromosomal deletion in these patients may be associated with a poor prognosis from the standpoint of cognitive development, and the potential for other structural abnormalities not normally associated with GCPS.     

MODY type 2 in Greig cephalopolysyndactyly syndrome (GCPS) as part of a contiguous gene deletion syndrome

Maturity-onset diabetes of the young type 2 (MODY2) is a form of monogenic diabetes, characterized by mild fasting hyperglycemia. MODY2 is caused by heterozygous mutations in the GCK gene that encodes the glucokinase enzyme. We describe the clinical features and the underlying genetic defect of MODY2 in a patient with atypical Greig cephalopolysyndactyly syndrome (GCPS). The patient presented with the limb formation and the craniofacial developmental abnormalities typical to GCPS, in addition to mental retardation and epilepsy (assigned as atypical syndrome). Fasting hyperglycemia in the diabetic range, impaired glucose tolerance, and lack of diabetes autoantibodies were compatible with MODY2. In order to delineate the genetic aberrations relevant both to MODY2 and Greig syndrome in this patient, we performed cytogenetic analysis, real-time PCR of the GCK gene, and comparative genomic hybridization (CGH) array. Cytogenetic study has shown a microscopic detectable deletion in the 7p13-15 chromosomal region. Real-time PCR demonstrated a deletion of the GCK gene in the patient but not her parents, and CGH array revealed a deleted region of approximately 12 Mb in the 7p13-15 region. This deleted region included GLI3 and GCK genes (where heterozygous mutations cause GCPS and MODY2, respectively), and many other contiguous genes. Our patient manifests a unique form of MODY2, where GCK gene deletion is part of a large deleted segment in the 7p13-15 chromosomal region.     

FGFR2 mutation in a patient with Apert syndrome associated with humeroradial synostosis

ABSTRACT  Most cases of Apert syndrome are due to S252W or P253R mutations in the fibroblast growth factor receptor 2 (FGFR2) gene. Differences in the effects of S252W and P253R mutations on the clinical features of Apert syndrome have been studied, but little is known about the type of FGFR2 mutation in Apert syndrome with humeroradial synostosis. To study a correlation between the FGFR2 mutations and the clinical complications, we examined the FGFR2 gene in a patient with Apert syndrome associated with humeroradial synostosis, and found that the mutation was S252W. This report suggested that S252W mutation in FGFR2 may cause humeroradial synostosis in Apert syndrome.     

Asymptomatic laryngeal malformations are common in patients with Pallister-Hall syndrome

Pallister-Hall syndrome (PHS) comprises hypothalamic hamartoma, polydactyly, pituitary dysfunction, laryngotracheal cleft, imperforate anus, and other anomalies. Some patients with PHS have a bifid epiglottis, a rare malformation. Greig cephalopolysyndactyly syndrome (GCPS) comprises polydactyly with craniofacial malformations without the PHS malformations. Both disorders are caused by mutations in the GLI3 gene. Laryngoscopy on 26 subjects with PHS showed that 15 had a bifid or cleft epiglottis (58%) and none of 14 subjects with GCPS had a cleft epiglottis. The malformed epiglottis was asymptomatic in all of the prospectively evaluated subjects. One additional PHS subject was found to have bifid epiglottis and a posterior laryngeal cleft on autopsy. We conclude that bifid epiglottis is common in PHS but not GCPS. Posterior laryngeal clefts are an uncommon manifestation of PHS and are identified only in severely affected patients. The diagnosis of a bifid epiglottis should prompt a thorough search for other sometimes asymptomatic anomalies of PHS to provide better medical care and recurrence risk assessment for affected individuals and families.