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.     

Patterns of dysmorphic features in schizophrenia.

Congenital dysmorphic features are prevalent in schizophrenia and may reflect underlying neurodevelopmental abnormalities. A cluster analysis approach delineating patterns of dysmorphic features has been used in genetics to classify individuals into more etiologically homogeneous subgroups. In the present study, this approach was applied to schizophrenia, using a sample with a suspected genetic syndrome as a testable model. Subjects (n = 159) with schizophrenia or schizoaffective disorder were ascertained from chronic patient populations (random, n = 123) or referred with possible 22q11 deletion syndrome (referred, n = 36). All subjects were evaluated for presence or absence of 70 reliably assessed dysmorphic features, which were used in a three-step cluster analysis. The analysis produced four major clusters with different patterns of dysmorphic features. Significant between-cluster differences were found for rates of 37 dysmorphic features (P < 0.05), median number of dysmorphic features (P = 0.0001), and validating features not used in the cluster analysis: mild mental retardation (P = 0.001) and congenital heart defects (P = 0.002). Two clusters (1 and 4) appeared to represent more developmental subgroups of schizophrenia with elevated rates of dysmorphic features and validating features. Cluster 1 (n = 27) comprised mostly referred subjects. Cluster 4 (n = 18) had a different pattern of dysmorphic features; one subject had a mosaic Turner syndrome variant. Two other clusters had lower rates and patterns of features consistent with those found in previous studies of schizophrenia. Delineating patterns of dysmorphic features may help identify subgroups that could represent neurodevelopmental forms of schizophrenia with more homogeneous origins.     

Patterns of dysmorphic features in schizophrenia

Congenital dysmorphic features are prevalent in schizophrenia and may reflect underlying neurodevelopmental abnormalities. A cluster analysis approach delineating patterns of dysmorphic features has been used in genetics to classify individuals into more etiologically homogeneous subgroups. In the present study, this approach was applied to schizophrenia, using a sample with a suspected genetic syndrome as a testable model. Subjects (n = 159) with schizophrenia or schizoaffective disorder were ascertained from chronic patient populations (random, n = 123) or referred with possible 22q11 deletion syndrome (referred, n = 36). All subjects were evaluated for presence or absence of 70 reliably assessed dysmorphic features, which were used in a three‐step cluster analysis. The analysis produced four major clusters with different patterns of dysmorphic features. Significant between–cluster differences were found for rates of 37 dysmorphic features (P < 0.05), median number of dysmorphic features (P = 0.0001), and validating features not used in the cluster analysis: mild mental retardation (P = 0.001) and congenital heart defects (P = 0.002). Two clusters (1 and 4) appeared to represent more developmental subgroups of schizophrenia with elevated rates of dysmorphic features and validating features. Cluster 1 (n = 27) comprised mostly referred subjects. Cluster 4 (n = 18) had a different pattern of dysmorphic features; one subject had a mosaic Turner syndrome variant. Two other clusters had lower rates and patterns of features consistent with those found in previous studies of schizophrenia. Delineating patterns of dysmorphic features may help identify subgroups that could represent neurodevelopmental forms of schizophrenia with more homogeneous origins. © 2001 Wiley‐Liss, Inc.     

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.     

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.     

Phenotype of five patients with Greig syndrome and microdeletion of 7p13

Here we describe five patients with Greig cephalopolysyndactyly syndrome (GCPS), including one pair of monozygotic twin boys with a de novo microdeletion involving the chromosomal band 7p13, where various clinical manifestations, in addition to GCPS, were recognized. Besides the twin pair, all patients are unrelated. Since there is a considerable lack of well-defined clinical delineation of the few patients with microdeletions involving 7p13 with GCPS described so far, we focus on the symptoms that are not typically related to GCPS, such as moderate psychomotor retardation, seizures, muscle fiber anomalies, cardiac anomalies, hyperglycemia, and hirsutism. Our observations suggest that in all cases of atypical GCPS, the presence of a cytogenetically detectable microdeletion or a submicroscopic deletion of 7p13 should be suspected.     

A girl with deletion 9q22.1-q22.32 including the PTCH and ROR2 genes identified by genome-wide array-CGH

The underlying genetic cause of mental retardation (MR) remains unknown in about half of the cases. Recently, using whole genome array comparative genomic hybridization (array-CGH), submicroscopic genetic imbalances have been detected in up to 20% of patients with an unexplained MR, dysmorphic features, and apparently normal karyotype. Here, we present a 12-year-old girl with features of basal cell nevus syndrome (BCNS), pulmonary valve stenosis, and MR, in whom array-CGH identified a 7.7 Mb deletion on 9q22.1-q22.32. The deleted region includes, among others, the ROR2 and PTCH genes. Haploinsufficiency of PTCH causes the BCNS syndrome and mutations in ROR2 have been found in an autosomal recessive Robinow syndrome and a dominantly inherited brachydactyly type 1B. We speculate that haploinsufficiency of ROR2 may contribute to pulmonary valve stenosis. Because of an age-dependent penetrance, BCNS may be challenging for diagnosis particularly when the features are not part of a typical clinical spectrum of BCNS. Early diagnosis of BCNS is important for preventing the development of associated tumors and better care of the patient. Our data confirm the previous observations that application of the whole genome array-CGH should be considered in selected patients with undiagnosed MR and dysmorphic features.     

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.      

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.     

Molecular characterization of an 11q interstitial deletion in a patient with the clinical features of Jacobsen syndrome

The 11q terminal deletion disorder or Jacobsen syndrome is a contiguous gene disorder. It is characterized by psychomotor retardation, cardiac defects, blood dyscrasias (Paris-Trousseau syndrome) and craniofacial anomalies. We report on a female patient with an approximately 10 Mb interstitial deletion with many of the features of Jacobsen syndrome: A congenital heart defect, dysmorphic features, developmental delay, and Paris-Trousseau syndrome. The karyotype of the patient is 46,XX,del(11)(q24.1q24.3). The interstitial deletion was confirmed using FISH probes for distal 11q, and the breakpoints were characterized by microarray analysis. This is the first molecularly characterized interstitial deletion in a patient with the clinical features of Jacobsen syndrome. The deletion includes FLI-1, but not JAM-3, which will help to determine the critical genes involved in this syndrome.     

Chromosomal localisation of a developmental gene in man: direct DNA analysis demonstrates that Greig cephalopolysyndactyly maps to 7p13

Greig cephalopolysyndactyly syndrome (GCPS) is a rare autosomal dominant form of complex polydactyly. GCPS has been tentatively assigned to chromosome 7 on the basis of association of the condition with balanced translocations involving the short arm of chromosome 7 (7p13) in two families. Seven GCPS pedigrees with no chromosome abnormality were studied, and linkage was demonstrated between GCPS and the DNA sequence coding for the receptor for epidermal growth factor (localised to 7p12-13) (Z = 3.17; O = theta).     

Two sisters with IMAGe syndrome: cytomegalic adrenal histopathology, support for autosomal recessive inheritance and literature review

Adrenal hypoplasia congenita (AHC) is a rare condition and causes primary adrenal insufficiency. X-linked (OMIM 300200) and autosomal recessive (OMIM 240200) forms are recognized. Recently, an association between Intrauterine growth restriction, Metaphyseal dysplasia, Adrenal hypoplasia congenita, and Genital abnormalities (IMAGe syndrome; OMIM 300290) has been described. We present the clinical features of two sisters with intrauterine growth restriction, AHC, and dysmorphic features. Interesting histopathologic findings of one sister are also presented. We suggest that IMAGe syndrome is the most plausible diagnosis and that autosomal recessive inheritance is likely. We analyzed genes that were postulated candidates for IMAGe syndrome (SF1, DAX-1, and STAR), and no mutations were found. Other cases of IMAGe syndrome are reviewed.     

Reversed clinical phenotype due to a microduplication of Sotos syndrome region detected by array CGH: microcephaly, developmental delay and delayed bone age

Haploinsufficiency of the NSD1 gene due to 5q35 microdeletions or intragenic mutations is the major cause of Sotos syndrome characterized by generalized overgrowth, large hands and feet with advanced bone age, craniofacial dysmorphic features, learning disability, and possible susceptibility to tumors. Here, we report on a 14-month-old boy with a reverse phenotype of Sotos syndrome due to the reciprocal duplication of the 5q35.3 region, including the NSD1 gene, detected by array CGH. The phenotype includes delayed bone age, microcephaly, seizures, and failure to thrive. Our case suggests that the gene dosage effect of the NSD1 gene is the likely cause for the reversed phenotype of Sotos syndrome in this patient.     

Metopic and sagittal synostosis in Greig cephalopolysyndactyly syndrome: five cases with intragenic mutations or complete deletions of GLI3

Greig cephalopolysyndactyly syndrome (GCPS) is a multiple congenital malformation characterised by limb and craniofacial anomalies, caused by heterozygous mutation or deletion of GLI3. We report four boys and a girl who were presented with trigonocephaly due to metopic synostosis, in association with pre- and post-axial polydactyly and cutaneous syndactyly of hands and feet. Two cases had additional sagittal synostosis. None had a family history of similar features. In all five children, the diagnosis of GCPS was confirmed by molecular analysis of GLI3 (two had intragenic mutations and three had complete gene deletions detected on array comparative genomic hybridisation), thus highlighting the importance of trigonocephaly or overt metopic or sagittal synostosis as a distinct presenting feature of GCPS. These observations confirm and extend a recently proposed association of intragenic GLI3 mutations with metopic synostosis; moreover, the three individuals with complete deletion of GLI3 were previously considered to have Carpenter syndrome, highlighting an important source of diagnostic confusion.     

Ring chromosome 17: phenotype variation by deletion size

Ring chromosome 17 is a rare cytogenetic abnormality, with 12 previous reports in the literature. Some have a relatively mild phenotype characterized by seizures, mental retardation, skin changes and short stature. Other patients have Miller-Dieker syndrome (MDS), which includes lissencephaly, multiple dysmorphic features, severe mental retardation and shortened life expectancy. We describe two new cases of ring chromosome 17 and review the literature. Our cases and the other reports of patients without a deletion encompassing the Miller-Dieker region, delineate a fairly distinctive subgroup of individuals with ring 17, whose phenotype consists of growth and mental retardation, seizures, minor dysmorphic features, café-au-lait spots and retinal flecks. This classification of ring 17 into two distinct groups based on the size of the deletion and the phenotypic manifestations should facilitate clinical suspicion of this rare chromosomal abnormality.     

Hoffman syndrome: New patients, new insights

Hypogammaglobulinemia or agammaglobulinemia are major features of specific syndromes, including X-linked agammaglobulinemia and common variable immunodeficiency. However, the combination of hypogammaglobulinemia with specific dysmorphic features is less common, with only a few reported cases. One such report was a sporadic case of humoral immunodeficiency, facial dysmorphism, and limb anomalies in a young girl, later referred to as Hoffman syndrome. We report on a 7-year-old girl with almost complete loss of B cells, facial dysmorphism, and malformation of the limbs and genitalia, whose mother shows similar dysmorphic features with an attenuated version of the B-cell deficiency. We believe that all three cases described above represent the same condition. The features of the three affected individuals with Hoffman syndrome are reviewed. Further investigations in this recently recognized B-cell immunodeficiency syndrome are warranted.     

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.     

Mosaic tetrasomy 5p resulting from an isochromosome 5p marker chromosome: case report and review of literature

We report on the fifth case, and oldest reported patient, of an individual affected with mosaic tetrasomy 5p resulting from an isochromosome 5p [i(5)(p10)] marker chromosome. A syndrome of mosaic tetrasomy 5p is defined, and includes the following features seen in the reported cases: developmental delay, seizures, ventriculomegaly (other brain anomalies), small stature/growth delay and mosaic pigmentary skin changes. Other findings include various dysmorphic facial features as well as hand and foot anomalies. This syndrome is likely more common than suggested in the literature, as the clinical presentation can be variable, and the chromosome anomaly is unlikely to be found on routine karyotype of peripheral blood lymphocytes. The i(5)(p10) marker chromosome is found only as a mosaic anomaly, with levels ranging from 0% to 10% in cultured lymphocytes to 12-85% in cultured skin fibroblasts. Microarray analysis performed on unstimulated lymphocytes from the patient in this report did not detect any evidence of the chromosome abnormality, indicating that this methodology may not be useful as a diagnostic tool in this disorder. Diagnosis of the mosaic tetrasomy 5p syndrome will rely on good clinical assessment, and appropriate cytogenetic studies, including analysis of skin fibroblasts. A child with unexplained developmental delay, seizures, hypotonia, and ventriculomegaly with or without dysmorphic features should be assessed carefully for pigmentary changes of the skin. If a diagnosis of mosaic 5p tetrasomy is suspected, karyotype of cultured fibroblasts in addition to routine cytogenetic analysis, to look for this marker chromosome is warranted.     

Testicular cancer in a patient with Primrose syndrome

A mentally retarded, adult man was found to have joint contractures, sparse body hair, hearing loss, dysmorphic facial features, large calcified pinnae and a huge torus palatinus. All features are similar to those earlier described in patients with Primrose syndrome. In addition he developed a germ cell tumour of his right testicle at age 27 years. A comparison is provided between the main findings in the four previously reported cases with Primrose syndrome and the current patient. Calcification of the pinnae is an infrequent symptom in the general population, and a torus palatinus of limited size is commonly found but a torus of the size reported here is extremely unusual. Both symptoms are excellent handles for diagnosing this entity. It remains as yet uncertain whether an increased risk to malignancies forms part of this syndrome or is only a consequence of cryptorchidism in this patient.