Molecular screening for microdeletions at 9p22-p24 and 11q23-q24 in a large cohort of patients with trigonocephaly

Craniosynostosis: current conceptions and misconceptions

Cranial bones articulate in areas called sutures that must remain patent until skull growth is complete. Craniosynostosis is the condition that results from premature closure of one or more of the cranial vault sutures, generating facial deformities and more importantly, skull growth restrictions with the ability to severely affect brain growth. Typically, craniosynostosis can be expressed as an isolated event, or as part of syndromic phenotypes. Multiple signaling mechanisms interact during developmental stages to ensure proper and timely suture fusion. Clinical outcome is often a product of craniosynostosis subtypes, number of affected sutures and timing of premature suture fusion. The present work aimed to review the different aspects involved in the establishment of craniosynostosis, providing a close view of the cellular, molecular and genetic background of these malformations.

A genome-wide association study implicates the BMP7 locus as a risk factor for nonsyndromic metopic craniosynostosis

Our previous genome-wide association study (GWAS) for sagittal nonsyndromic craniosynostosis (sNCS) provided important insights into the genetics of midline CS. In this study, we performed a GWAS for a second midline NCS, metopic NCS (mNCS), using 215 non-Hispanic white case-parent triads. We identified six variants with genome-wide significance (P ≤ 5 × 10-8): rs781716 (P = 4.71 × 10-9; odds ratio [OR] = 2.44) intronic to SPRY3; rs6127972 (P = 4.41 × 10-8; OR = 2.17) intronic to BMP7; rs62590971 (P = 6.22 × 10-9; OR = 0.34), located ~ 155 kb upstream from TGIF2LX; and rs2522623, rs2573826, and rs2754857, all intronic to PCDH11X (P = 1.76 × 10-8, OR = 0.45; P = 3.31 × 10-8, OR = 0.45; P = 1.09 × 10-8, OR = 0.44, respectively). We performed a replication study of these variants using an independent non-Hispanic white sample of 194 unrelated mNCS cases and 333 unaffected controls; only the association for rs6127972 (P = 0.004, OR = 1.45; meta-analysis P = 1.27 × 10-8, OR = 1.74) was replicated. Our meta-analysis examining single nucleotide polymorphisms common to both our mNCS and sNCS studies showed the strongest association for rs6127972 (P = 1.16 × 10-6). Our imputation analysis identified a linkage disequilibrium block encompassing rs6127972, which contained an enhancer overlapping a CTCF transcription factor binding site (chr20:55,798,821-55,798,917) that was significantly hypomethylated in mesenchymal stem cells derived from fused metopic compared to open sutures from the same probands. This study provides additional insights into genetic factors in midline CS.

Incidence of Familial Craniosynostosis Among Patients With Nonsyndromic Craniosynostosis

BACKGROUND

Craniosynostosis has an incidence of 1 in 2000 to 2500 live births, and is categorized into syndromic and nonsyndromic types. Nonsyndromic ones can be familial in which more than one of the family members are involved.

METHODS

This is a prospective study which is carried out from April 2015 to January 2018 in 2 academic hospitals. Those patients who had nonsyndromic craniosynostosis and completed medical follow-up were included in the study as well as their 1st degree relatives. Age of patients, gender, existing consanguineous marriage, type of deliveries, type of pregnancy (assisted reproductive technologies [ART] versus sexual intercourse), severity and type of craniosynostosis were gathered.

RESULTS

Ninety-four (46.0%), 58 (28.4%), 28 (13.7%), 16 (7.8%), and 8 (3.9%) of patients had trigonocephaly, scaphocephaly, anterior plagiocephaly, complex, and brachycephaly, respectively. A total number of 204 patients were included in the study. Of all 204 families which were included, 30 (14.7%) families had positive familial history. Familial patients were determined in 10, 15, 8, 1, and 5 patients with scaphocephaly, trigonocephaly, anterior plagiocephaly, rachycephaly, and mixed type. Male to female ratio was 2:1, 1.9:1, 1.3:1, 1:1, and 1:1 for scaphocephaly, trigonocephaly, anterior plagiocephaly, brachycephaly, and mixed craniosynostosis. Twelve (5.9%) women had applied ART.

CONCLUSION

Present study reveals that metopic suture is the most frequent craniosynostosis within nonsyndromic types. All the types of nonsyndromic craniosynostosis had male prevalence but for complex one which was equal in both gender. Nonsyndromic craniosynostosis in about 14.7% of patients was familial.

A 46,XY Female with a 9p24.3p24.1 Deletion and a 8q24.11q24.3 Duplication: A Case Report and Review of the Literature

Deletion of distal 9p is associated with a rare clinical condition characterized by dysmorphic features, developmental delay, and ambiguous genitalia. The phenotype shows variable expressivity and is related to the size of the deletion. 8q24 duplication has been reported in only few cases to date, all showing dysmorphic features and mild psychomotor developmental delay. A case of chromosomal aberration involving a 9p terminal deletion with an 8q duplication has never been reported. Here, we describe a child with a female phenotype, male karyotype, dysmorphic features, ambiguous genitalia, and developmental delay. In order to assess the cause of the patient's phenotype, conventional karyotyping, FISH, and a chromosomal microarray analysis were performed on the patient and her parents. The cytogenetic and molecular analysis revealed an unbalanced chromosomal aberration with a duplication in the long arm of chromosome 8 at 8q24.11q24.3 associated with a distal deletion in the short arm of chromosome 9 at 9p24.3p24.1, derived from a maternal balanced translocation. We compared the clinical picture of our patient with other similar cases reported in the literature and found that some clinical findings, such as strabismus, symphalangism of the first finger, and cubitus valgus, have never been previously associated with 9p deletion or 8q duplication expanding the phenotypic range of this condition. This study is aimed to better define the clinical history and prognosis of patients with this rare chromosomal aberration.

Health-related quality of life in children after surgical treatment of non-syndromal craniosynostosis

PURPOSE

Craniosynostosis is a premature ossification of the fibrous sutures in a skull which results in a changing of the growth pattern of the skull with abnormal head shapes, midface hypoplasia, and neurofunctional disorders. Surgical correction of craniosynostosis by opening the ossified cranial sutures is usually made in the infant phase to avoid compression of the brain and mental deficits. However, little is known regarding the health-related quality of life among children after surgical treatment of diverse forms of craniosynostosis. The purpose of this study was to evaluate the quality of life of adolescent patients who anderwent a surgical correction of non-syndromal craniosynostosis in infancy.

MATERIALS AND METHODS

The study population included 48 adolescents with an average age of 12.1 ± 4.3 years. The KINDL questionnaire, which was specifically validated for children, was used to estimate different dimensions of quality of life and the impact of various factors on it.

RESULTS

In the investigated group, boys were more likely to be affected by non-syndromal craniosynostosis than were girls. Children and their parents showed a high degree of correlation in each of the investigated dimensions of the KINDL questionnaire. Sex, the type of craniosynostosis, surgical technique, and surgical result did not seem to have an influence on the quality of life. A negative correlation between the time of surgery and the family-related quality of life could be shown. None of the patients in the study had relevant limitations or impairments in their later life.

CONCLUSIONS

In our study, patients with simple non-syndromic craniosynostoses who anderwent operative correction of craniosynostosis in infancy do not show any quality-of-life limitations in their later life compared to the average population.

The Etiology of Neuronal Development in Craniosynostosis: A Working Hypothesis

Craniosynostosis is one of the most common craniofacial conditions treated by neurologic and plastic surgeons. In addition to disfigurement, children with craniosynostosis experience significant cognitive dysfunction later in life. Surgery is performed in infancy to correct skull deformity; however, the field is at a crossroads regarding the best approach for correction. Since the cause of brain dysfunction in these patients has remained uncertain, the role and type of surgery might have in attenuating the later-observed cognitive deficits through impact on the brain has been unclear. Recently, however, advances in imaging such as event-related potentials, diffusion tensor imaging, and functional MRI, in conjunction with more robust clinical studies, are providing important insight into the potential etiologies of brain dysfunction in syndromic and nonsyndromic craniosynostosis patients. This review aims to outline the cause(s) of such brain dysfunction including the role extrinsic vault constriction might have on brain development and the current evidence for an intrinsic modular developmental error in brain development. Illuminating the cause of brain dysfunction will identify the role of surgery can play in improving observed functional deficits and thus direct optimal primary and adjuvant treatment.

The Morphological Grading and Comparison of Sutural Patency Among Cranial Sutures in Dry Human Skulls

OBJECTIVE

To investigate the degree of fusion (patency) among cranial sutures in human dry skulls in the Anatolia.

METHODS

One-hundred fifty-eight human dry skulls that were accepted as adults according to the teeth eruption were macroscopically examined and photographed with Canon 400B (55 mm objective). The grades of fusion of coronal, sagittal, and lambdoid were quantitatively analyzed by using the modified grading scale. According to the extent of patency, the sutures were graded as grade-0 (open), grade-1 (fused but not obliterated), grade-2 (50%< obliterated), grade-3 (50% > obliterated), and grade-4 (100% obliterated). The authors determined and compared the rate for each grade of sutural patency on coronal, sagittal, and lambdoid sutures.

RESULTS

The cranial sutures of 4 cranii (4/158; 2.53%) had grade-4 fusion, whereas there were no any cranii with sutures of grade-0 fusion. The number of each grade of fusion among cranial sutures of 158 skulls, in descending order, was as follows: 171 (grade-3), 145 (grade-1), 133 (grade-2), and 25 (grade-4). The grade-4 fusion was significantly less observed than the others. The grade-1 and grade-4 fusion of lambdoid sutures were established as the most (66/41.8%) and least (5/3.2%) common fusions among cranial sutures, respectively. The frequencies of each grade of fusion for each cranial suture were determined in a descending order: coronal (grade-3 > 2 > 1 > 4), sagittal (grade-3 > 2 > 1 > 4), and lambdoid sutures (grade-1 > 3 > 2 > 4). The frequency of grade-1 fusion of lambdoid suture (66/41.8%) was significantly different when compared with coronal (39/24.7%) and sagittal sutures (40/25.3%), respectively.

CONCLUSION

The grades of fusion (or sutural patency) vary among cranial sutures.

Genetic advances in craniosynostosis

Craniosynostosis, the premature ossification of one or more skull sutures, is a clinically and genetically heterogeneous congenital anomaly affecting approximately one in 2,500 live births. In most cases, it occurs as an isolated congenital anomaly, that is, nonsyndromic craniosynostosis (NCS), the genetic, and environmental causes of which remain largely unknown. Recent data suggest that, at least some of the midline NCS cases may be explained by two loci inheritance. In approximately 25-30% of patients, craniosynostosis presents as a feature of a genetic syndrome due to chromosomal defects or mutations in genes within interconnected signaling pathways. The aim of this review is to provide a detailed and comprehensive update on the genetic and environmental factors associated with NCS, integrating the scientific findings achieved during the last decade. Focus on the neurodevelopmental, imaging, and treatment aspects of NCS is also provided.

Evidence that homozygous PTPRD gene microdeletion causes trigonocephaly, hearing loss, and intellectual disability

Background

The premature fusion of metopic sutures results in the clinical phenotype of trigonocephaly. An association of this characteristic with the monosomy 9p syndrome is well established and the receptor-type protein tyrosine phosphatase gene (PTPRD), located in the 9p24.1p23 region and encoding a major component of the excitatory and inhibitory synaptic organization, is considered as a good candidate to be responsible for this form of craniosynostosis. Moreover PTPRD is known to recruit multiple postsynaptic partners such as IL1RAPL1 which gene alterations lead to non syndromic intellectual disability (ID).

Results

We describe a 30 month old boy with severe intellectual disability, trigonocephaly and dysmorphic facial features such as a midface hypoplasia, a flat nose, a depressed nasal bridge, hypertelorism, a long philtrum and a drooping mouth.

Microarray chromosomal analysis revealed the presence of a homozygous deletion involving the PTPRD gene, located on chromosome 9p22.3. Reverse Transcription PCR (RT-PCR) amplifications all along the gene failed to amplify the patient's cDNA in fibroblasts, indicating the presence of two null PTPRD alleles.

Synaptic PTPRD interacts with IL1RAPL1 which defects have been associated with intellectual disability (ID) and autism spectrum disorder. The absence of the PTPRD transcript leads to a decrease in the expression of IL1RAPL1. These results suggest the direct involvement of PTPRD in ID, which is consistent with the PTPRD -/- mice phenotype.

Deletions of PTPRD have been previously suggested as a cause of trigonocephaly in patients with monosomy 9p and genome-wide association study suggested variations in PTPRD are associated with hearing loss.

Conclusions

The deletion identified in the reported patient supports previous hypotheses on its function in ID and hearing loss. However, its involvement in the occurrence of metopic synostosis is still to be discussed as more investigation of patients with the 9p monosomy syndrome is required.

Clinical characteristics and surgical decision making for infants with metopic craniosynostosis in conjunction with other congenital anomalies

Background:

Metopic craniosynostosis can occur in isolation or in conjunction with other congenital anomalies. The surgical decision making and outcomes between these 2 groups are analyzed.

Methods:

A retrospective review of all children evaluated in the craniofacial clinic at Seattle Children’s Hospital for metopic craniosynostosis between 2004 and 2009 was performed. Physical examination and CT scan characteristics were analyzed as were the treatment decisions and surgical outcomes.

Results:

From 2004 to 2009, 282 patients were evaluated and 100 were determined to have metopic craniosynostosis. Of these, 19 patients were found to have additional congenital anomalies. Review of these patients’ CT scans revealed 13 with classic trigonencephaly, 3 with microcephaly, and 3 with narrow frontal bones, abnormal orbits, and small anterior fossa. Patients (90%) with isolated metopic craniosynostosis underwent cranial vault expansion, whereas only 63% of the complex group did so. The complex metopic group had a longer hospital stay (5 d vs 3.4 d), more intraoperative complications, and required more repeat surgery.

Conclusion:

Patients with metopic craniosynostosis and additional anomalies require special consideration when deciding upon surgical intervention and should be cared for by a multidisciplinary team to address their additional needs.

Familial incidence and associated symptoms in a population of individuals with nonsyndromic craniosynostosis

PURPOSE

Craniosynostosis is a common cranial malformation occurring in 1 per 2,000-2,500 births. Isolated defects (nonsyndromic) occur in ~75% of cases and are thought to have multifactorial etiology. It is believed that each suture synostosis is a distinct disease, with varying phenotypes and recurrence rates.

METHODS

We analyzed family histories of 660 mutation-negative nonsyndromic craniosynostosis patients and symptoms in 189 of these patients.

RESULTS

The incidence rate of craniosynostosis was highest for first-degree relatives of probands with metopic craniosynostosis (6.4%), followed by those with complex craniosynostosis (4.9%), sagittal craniosynostosis (3.8%), lambdoid craniosynostosis (3.9%), and coronal craniosynostosis (0.7%). Across all suture types, siblings had a greater craniosynostosis incidence rate than parents (7.5 vs. 2.3%). In phenotype comparisons, patients with complex craniosynostosis had the highest frequency of reported symptoms and those with sagittal craniosynostosis had the lowest. Ear infections, palate abnormalities, and hearing problems were more common in complex craniosynostosis patients. Visual problems were more common in coronal craniosynostosis, and metopic craniosynostosis patients noted increased frequency of chronic cough.

CONCLUSION

Our data suggest that the genetic component of nonsyndromic craniosynostosis appears to be suture specific. The incidence rate of craniosynostosis among first-degree relatives varies by suture and family member. Additionally, the phenotype of each suture synostosis shows both unique and shared features.

Genetic basis of single-suture synostoses: genes, chromosomes and clinical implications

BACKGROUND

Non syndromic craniosynostoses are the most frequent craniofacial malformations worldwide. They represent a wide and heterogeneous group of entities, in which the dysmorphism may occur in a single (simple forms) or in multiple sutures (complex forms). Simple forms present a higher birth prevalence and are classified according to the involved suture and to the corresponding abnormal cranial shape: scaphocephaly (SC; sagittal suture), trigonocephaly (TC; metopic suture), anterior plagiocephaly (unilateral coronal suture), posterior plagiocephaly (unilateral lambdoid suture). They occur commonly as sporadic forms, although a familiar recurrence is sometimes observed, suggesting a mendelian inheritance. The genetic causes of simple craniosynostosis are still largely unknown, as mutations in common craniosynostosis-associated genes and structural chromosomal aberrations have been rarely found in these cases.

AIMS

This review is intended to dissect comprehensively the state-of-the art on the genetic etiology of single suture craniosynostoses, in the attempt to categorize all known disease-associated genes and chromosomal aberrations. Possible genotype/phenotype correlations are discussed as useful clues towards the definition of optimized clinical management flowcharts.

Metopic synostosis

Premature closure of the metopic suture results in a growth restriction of the frontal bones, which leads to a skull malformation known as trigonocephaly. Over the course of recent decades, its incidence has been rising, currently making it the second most common type of craniosynostosis. Treatment consists of a cranioplasty, usually preformed before the age of 1 year. Metopic synostosis is linked with an increased level of neurodevelopmental delays. Theories on the etiology of these delays range from a reduced volume of the anterior cranial fossa to intrinsic malformations of the brain. This paper aims to provide an overview of this entity by giving an update on the epidemiology, etiology, evolution of treatment, follow-up, and neurodevelopment of metopic synostosis.

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.

Craniosynostosis

Craniosynostosis, defined as the premature fusion of the cranial sutures, presents many challenges in classification and treatment. At least 20% of cases are caused by specific single gene mutations or chromosome abnormalities. This article maps out approaches to clinical assessment of a child presenting with an unusual head shape, and illustrates how genetic analysis can contribute to diagnosis and management.

Etiological heterogeneity and clinical characteristics of metopic synostosis: Evidence from a tertiary craniofacial unit

Metopic synostosis (MS) accounts for approximately 10-15% of all craniosynostosis and is etiologically heterogeneous. This study aimed to examine the causes of MS, as observed in a tertiary craniofacial unit. We reviewed the case notes of 110 children with a diagnosis of MS, attending the craniofacial unit in Oxford between 1991 and 2008. Our results showed 38 children (38/110 or 34.6%) who had at least one additional structural abnormality or had a known syndromic diagnosis were classed as having syndromic MS. Chromosomal abnormalities were noted in 8/38 (21.4%) children: mosaic marker chromosome 2, 9p deletion (2/8), 11q deletion, 12pter deletion and duplication of 15q25 with other additional chromosomal abnormalities (3/8). Other syndromic diagnoses included Silver-Russell syndrome and Greig cephalopolysyndactyly. Prenatal exposure to sodium valproate (VPA) was noted in 8/110 children (7.8%), with the dose of the VPA being >or=1,000 mg/day in all cases. Other prenatal exposures reported in this study were: maternal diabetes (6/110), enoxaparin for hypercoagulable state (1/110), and thyroxine (1/110). The majority of patients (72/110 or 65.4%) had nonsyndromic MS. Speech delay was present in 11 children with nonsyndromic MS (11/72 or 15.3%) and 10 children with syndromic MS (10/38 or 26.3%). We conclude that approximately two-thirds of all MS is nonsyndromic. Prenatal exposure to VPA is a common cause of MS. Maternal diabetes, not previously linked to MS, was noted in 5.5% of cases. Chromosomal abnormalities account for about 6% of MS. An increased risk of speech delay is seen with both the syndromic and nonsyndromic forms.

Prevalence and complications of single-gene and chromosomal disorders in craniosynostosis

OBJECTIVES

We describe the first cohort-based analysis of the impact of genetic disorders in craniosynostosis. We aimed to refine the understanding of prognoses and pathogenesis and to provide rational criteria for clinical genetic testing.

METHODS

We undertook targeted molecular genetic and cytogenetic testing for 326 children who required surgery because of craniosynostosis, were born in 1993-2002, presented to a single craniofacial unit, and were monitored until the end of 2007.

RESULTS

Eighty-four children (and 64 relatives) had pathologic genetic alterations (86% single-gene mutations and 14% chromosomal abnormalities). The FGFR3 P250R mutation was the single largest contributor (24%) to the genetic group. Genetic diagnoses accounted for 21% of all craniosynostosis cases and were associated with increased rates of many complications. Children with an initial clinical diagnosis of nonsyndromic craniosynostosis were more likely to have a causative mutation if the synostoses were unicoronal or bicoronal (10 of 48 cases) than if they were sagittal or metopic (0 of 55 cases; P = .0003). Repeat craniofacial surgery was required for 58% of children with single-gene mutations but only 17% of those with chromosomal abnormalities (P = .01).

CONCLUSIONS

Clinical genetic assessment is critical for the treatment of children with craniosynostosis. Genetic testing of nonsyndromic cases (at least for FGFR3 P250R and FGFR2 exons IIIa/c) should be targeted to patients with coronal or multisuture synostoses. Single-gene disorders that disrupt physiologic signaling in the cranial sutures often require reoperation, whereas chromosomal abnormalities follow a more-indolent course, which suggests a different, secondary origin of the associated craniosynostosis.

Cytogenetic and array-CGH characterization of a complex de novo rearrangement involving duplication and deletion of 9p and clinical findings in a 4-month-old female

Approximately 15 patients with partial trisomy 9p involving de novo duplications have been previously described. Here, we present clinical, cytogenetic, FISH and aCGH findings in a patient with a de novo complex rearrangement in the short arm of chromosome 9 involving an inverted duplication at 9p24→p21.3 and a deletion at 9pter→p24.2. FISH probes generated from BACs selected from the UCSC genome browser were utilized to verify this rearrangement. It is likely that some previously described duplications of 9p may also be products of complex chromosomal aberrations. This report in which FISH and aCGH were used to more comprehensively characterize the genomic rearrangement in a patient with clinical manifestations of 9p duplication syndrome underscores the importance of further characterizing cytogenetically detected rearrangements.

Clinical and cytogenetic characterization of 13 Dutch patients with deletion 9p syndrome: Delineation of the critical region for a consensus phenotype

The deletion 9p syndrome is caused by a constitutional monosomy of part of the short arm of chromosome 9. It is clinically characterized by dysmorphic facial features (trigonocephaly, midface hypoplasia, and long philtrum), hypotonia and mental retardation. Deletion 9p is known to be heterogeneous and exhibits variable deletion sizes. The critical region for a consensus phenotype has been reported to be located within a approximately 4-6 Mb interval on 9p22. In the present study, deletion breakpoints were determined in 13 Dutch patients by applying fluorescence in situ hybridization (FISH) and in some specific cases by array-based comparative genomic hybridization (array CGH). No clear genotype-phenotype correlation could be established for various developmental features. However, we were able to narrow down the critical region for deletion 9p syndrome to approximately 300 kb. A functional candidate gene for trigonocephaly, the CER1 gene, appeared to be located just outside this region. Sequence analysis of this gene in nine additional patients with isolated trigonocephaly did not reveal any pathogenic mutations.

Craniosynostosis associated with distal 5q-trisomy: further evidence that extra copy of MSX2 gene leads to craniosynostosis

Distal 5q-trisomy has been reported in less than 30 patients, with craniosynostosis present in five. We report two new patients with distal 5q-trisomy craniosynostosis. Patient 1 had mild Kleeblattschädel with synostosis of multiple sutures together with wide and medially deviated thumbs and halluces, indicative of Pfeiffer syndrome. Cytogenetic and CGH analyses showed a karyotype of 46,XY,der(10)t(5;10)(q33;q26.3). Patient 2 had a prominent forehead and ridging of the metopic suture. Craniosynostosis of the metopic suture was shown by CT scan. Cytogenetic and CGH analyses disclosed a karyotype of 46,XX,der(17)t(5;17)(q35.1;p13.3). Of the 22 previously reported patients, all had microcephaly and 14 had an abnormal skull shape. Our results support the previous finding that distal 5q-trisomy together with an extra copy of the MSX2 gene leads to abnormal closure of sutures and craniosynostosis.

Maternal thyroid disease as a risk factor for craniosynostosis

OBJECTIVE

To study the relationship between maternal thyroid disease and craniosynostosis using data from the National Birth Defects Prevention Study, a multisite, case-control study.

METHODS

Case infants (n=431) were identified through population-based birth defects surveillance systems at eight sites and had craniosynostosis verified by radiographic imaging. Control infants (n=4,094) consisted of a random sample of live births with no major birth defects from the same population as the case infants. Information on thyroid disease was based on self-report: mothers who reported either a thyroid disorder or use of a medication to treat a thyroid disorder during pregnancy were considered to have thyroid disease. Using an unconditional logistic regression model, we considered potential confounding factors (maternal age, race or ethnicity, smoking, body mass index, preexisting diabetes, plurality, gravidity, family history, infant sex).

RESULTS

Among case mothers, 19 (4.4%) were classified as having thyroid disease, compared with 65 (1.6%) of control mothers. Maternal thyroid disease was associated with craniosynostosis after controlling for maternal age (adjusted odds ratio 2.47, 95% confidence interval 1.46-4.18), the only factor that remained significant in the final model.

CONCLUSION

These data provide additional evidence that maternal thyroid disease (most likely Graves' disease) or its treatment is associated with craniosynostosis. Given the frequency of maternal thyroid disease, this association warrants further investigation.

LEVEL OF EVIDENCE

II.

Antenatal diagnosis of deletion chromosome 11(q23-qter) (Jacobsen syndrome)

A case of Jacobsen syndrome, suspected antenatally on the grounds of trigonocephaly and hypoplastic left heart syndrome, is presented. Clinicians are reminded that a hypoplastic left heart should not be assumed to be an isolated malformation and that a careful search for associated malformations can facilitate the recognition of an underlying genetic syndrome.

Genetic analysis of non-syndromic craniosynostosis

Craniosynostosis is a common malformation occurring in 3-5 per 10,000 live births. Most often craniosynostosis occurs as an isolated (i.e. non-syndromic) anomaly. Non-syndromic craniosynostosis (NSC) is a clinically and genetically heterogeneous condition that has the characteristics of a multifactorial trait. It is believed that each sutural synostosis (e.g. sagittal, coronal) represents a different disease. Significant progress has been made in understanding the clinical and molecular aspects of monogenic syndromic craniosynostosis. However, the phenotypic characterization of NSC is incomplete and its causes remain unknown. This review summarizes the available knowledge on NSC and presents a systematic approach aimed at the identification of genetic and non-genetic factors contributing to the risk of this common craniofacial defect.

Novel aphidicolin-inducible common fragile siteFRA9G maps to 9p22.2, within theC9orf39 gene

Common fragile sites represent a component of normal chromosome structure that form gaps and breaks on metaphase chromosomes after partial inhibition of DNA synthesis. In humans, cytogenetic locations of 89 common fragile sites are listed in the Genome Database; however, the exact number of fragile sites remains unknown. The application of high resolution mapping approaches continues to reveal new common fragile sites in the human genome. Here, we identified a novel aphidicolin-inducible common fragile site FRA9G, which maps to chromosomal band 9p22.2. We have characterized the structure of the fragile DNA sequence that extends over a genomic region of approximately 300 kb within the C9orf39 (chromosome 9 open reading frame 39) gene. Analysis of incidence in healthy individuals showed that FRA9G is commonly expressed in the population. Heterozygous BRCA2 mutation carriers exhibit an almost sevenfold increase of FRA9G expression compared to an unrelated control population group. Identification of a novel aphidicolin-inducible common fragile site at 9p22 may have implications for understanding the mechanism of genetic instability in tumorigenesis and other genetic disorders.

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.

An Xq22.3 duplication detected by comparative genomic hybridization microarray (Array-CGH) defines a new locus (FGS5) for FG syndrome

FG syndrome is an X-linked multiple congenital anomalies (MCA) syndrome. It has been mapped to four distinct loci FGS1-4, through linkage analysis (Xq13, Xp22.3, and Xp11.4-p11.3) and based on the breakpoints of an X chromosome inversion (Xq11:Xq28), but so far no gene has been identified. We describe a boy with FG syndrome who has an inherited duplication at band Xq22.3 detected by comparative genomic hybridization microarray (Array-CGH). These duplication maps outside all four loci described so far for FG syndrome, representing therefore a new locus, which we propose to be called FGS5. MID2, a gene closely related to MID1, which is known to be mutated in Opitz G/BBB syndrome, maps within the duplicated segment of our patient. Since FG and Opitz G/BBB syndromes share many manifestations we considered MID2 a candidate gene for FG syndrome. We also discuss the involvement of other potential genes within the duplicated segment and its relationship with clinical symptoms of our patient, as well as the laboratory abnormalities found in his mother, a carrier of the duplication.

Mutational screening of FGFR1, CER1, and CDON in a large cohort of trigonocephalic patients

OBJECTIVE

Screen the known craniosynostotic related gene, FGFR1 (exon 7), and two new identified potential candidates, CER1 and CDON, in patients with syndromic and nonsyndromic metopic craniosynostosis to determine if they might be causative genes.

DESIGN

Using single-strand conformational polymorphisms (SSCPs), denaturing high-performance liquid chromatography, and/or direct sequencing, we analyzed a total of 81 patients for FGFR1 (exon 7), 70 for CER1, and 44 for CDON.

PATIENTS

Patients were ascertained in the Centro de Estudos do Genoma Humano in São Paulo, Brazil (n = 39), the Craniofacial Unit, Oxford, U.K. (n = 23), and the Johns Hopkins University, Baltimore, Maryland (n = 31). Clinical inclusion criteria included a triangular head and/or forehead, with or without a metopic ridge, and a radiographic documentation of metopic synostosis. Both syndromic and nonsyndromic patients were studied.

RESULTS

No sequence alterations were found for FGFR1 (exon 7). Different patterns of SSCP migration for CER1 compatible with the segregation of single nucleotide polymorphisms reported in the region were identified. Seventeen sequence alterations were detected in the coding region of CDON, seven of which are new, but segregation analysis in parents and homology studies did not indicate a pathological role.

CONCLUSIONS

FGFR1 (exon 7), CER1, and CDON are not related to trigonocephaly in our sample and should not be considered as causative genes for metopic synostosis. Screening of FGFR1 (exon 7) for diagnostic purposes should not be performed in trigonocephalic patients.

Narrowing candidate region for monosomy 9p syndrome to a 4.7-Mb segment at 9p22.2-p23

A 2-year-old boy with clinical manifestations of monosomy 9p syndrome and brown hair is described. G-banding and chromosome FISH studies demonstrated complex rearrangements involving seven breakpoints in chromosomes 2 and 9, which included a 6.6-Mb deletion at 9p22.2-p23. This, together with previous studies in the literature, narrowed the shortest region of overlap (SRO) for the syndrome to a 4.7-Mb interval. Candidate genes for trigonocephaly, mental retardation, and brown hair are discussed.