Overt cleft palate phenotype and TBX1 genotype correlations in velo-cardio-facial/DiGeorge/22q11.2 deletion syndrome patients.

Velo-cardio-facial syndrome/DiGeorge syndrome, also known as 22q11.2 deletion syndrome (22q11DS) is the most common microdeletion syndrome, with an estimated incidence of 1/2,000-1/4,000 live births. Approximately 9-11% of patients with this disorder have an overt cleft palate (CP), but the genetic factors responsible for CP in the 22q11DS subset are unknown. The TBX1 gene, a member of the T-box transcription factor gene family, lies within the 22q11.2 region that is hemizygous in patients with 22q11DS. Inactivation of one allele of Tbx1 in the mouse does not result in CP, but inactivation of both alleles does. Based on these data, we hypothesized that DNA variants in the remaining allele of TBX1 may confer risk to CP in patients with 22q11DS. To test the hypothesis, we evaluated TBX1 exon sequencing (n = 360) and genotyping data (n = 737) with respect to presence (n = 54) or absence (n = 683) of CP in patients with 22q11DS. Two upstream SNPs (rs4819835 and rs5748410) showed individual evidence for association but they were not significant after correction for multiple testing. Associations were not identified between DNA variants and haplotypes in 22q11DS patients with CP. Overall, this study indicates that common DNA variants in TBX1 may be nominally causative for CP in patients with 22q11DS. This raises the possibility that genes elsewhere on the remaining allele of 22q11.2 or in the genome could be relevant.

Bilateral oblique facial clefts and extremity anomaly in an infant after intrauterine efavirenz exposure and review of its teratogenic risk.

OBJECTIVE: Congenital anomalies may be caused by genetic or environmental factors or a combination of both. Oblique facial clefts are very rare congenital deformities. The occurrence of facial clefts and an extremity anomaly suggests a common underlying cause. Lateral oro-ocular clefts do not occur along normal developmental planes and may be part of the amnion disruption complex sequence. Our objective was to report a case of this very event, which also followed an unusual intrauterine exposure and review the literature on the teratogenic risk of efavirenz. STUDY DESIGN: We report a case of amniotic rupture sequence after fetal HIV and antiretroviral exposure. RESULT: Teratogenic exposure has been rarely reported and never after antiretroviral exposure. CONCLUSION: By reporting and registering more cases, we will be able to better assess the risks such medications pose to the developing fetus. The publication of a single case report has the potential to contribute to our knowledge of the significance of prenatal exposure to antiretrovirals and other medications for common HIV-associated disorders. It also generates a hypothesis that can be tested with further clinical data, animal models and epidemiologic studies.

Germline mosacism in Shprintzen-Goldberg syndrome.

We report on maternal half-sibs born to unaffected, non-consanguineous parents with classical Shprintzen-Goldberg syndrome (SGS) who had in addition intestinal malrotation and an aberrant subclavian artery. In one other SGS family germline mosaicism has been described. SGS is molecularly heterogeneous and has been linked to mutations in three genomic loci. This suggests there may be multiple other genetic factors that result in a common clinical phenotype and a number of investigators have implicated a fourth region (15q25-qter) in the etiology of SGS.

Exome sequence identifies RIPK4 as the Bartsocas-Papas syndrome locus.

Pterygium syndromes are complex congenital disorders that encompass several distinct clinical conditions characterized by multiple skin webs affecting the flexural surfaces often accompanied by craniofacial anomalies. In severe forms, such as in the autosomal-recessive Bartsocas-Papas syndrome, early lethality is common, complicating the identification of causative mutations. Using exome sequencing in a consanguineous family, we identified the homozygous mutation c.1127C>A in exon 7 of RIPK4 that resulted in the introduction of the nonsense mutation p.Ser376X into the encoded ankyrin repeat-containing kinase, a protein that is essential for keratinocyte differentiation. Subsequently, we identified a second mutation in exon 2 of RIPK4 (c.242T>A) that resulted in the missense variant p.Ile81Asn in the kinase domain of the protein. We have further demonstrated that RIPK4 is a direct transcriptional target of the protein p63, a master regulator of stratified epithelial development, which acts as a nodal point in the cascade of molecular events that prevent pterygium syndromes.

The proximal chromosome 14q microdeletion syndrome: delineation of the phenotype using high resolution SNP oligonucleotide microarray analysis (SOMA) and review of the literature.

We report on two patients with overlapping small interstitial deletions involving regions 14q12 to 14q13.1. Both children had severe developmental delay, failure to thrive, microcephaly, and distinctive facial features, including abnormal spacing of the eyes, epicanthal folds, sloping forehead, low-set ears, rounded eyebrows with triangular media aspect and outer tapering, depressed and broad nasal bridge, small mouth, a long philtrum, and a prominent Cupid's bow. Brain MRI of both children showed partial agenesis of the corpus callosum. Our first patient had bilateral hypoplastic optic nerves causing blindness, mild hearing impairment, sinus arrhythmia, abnormal temperature regulation, frequent apneic episodes, myoclonic jerks, and opisthotonus. Our second patient had a seizure disorder confirmed by EEG, sleep apnea, chronic interstitial lung disease, and several episodes of pneumonia and gastroenteritis. Cytogenetic analysis showed a normal karyotype in Patient 1 and a unique apparently balanced three-way translocation in Patient 2 involving chromosomes 4, 14, and 11. High resolution SNP Oligonucleotide Microarray Analysis (SOMA) revealed a deletion in the proximal region of chromosome 14q overlapping with the deletion of our first patient, and no copy number changes in chromosomes 4 and 11. Here, we review and compare published cases with a deletion involving the 14q12-22.1 chromosomal region in an effort to correlate phenotype and genotype. We also examine the underlying genomic architecture to identify the possible mechanism of the chromosomal abnormality. Our review found a patient with a mirror duplication of our first patient's deletion, confirming the existence of an underlying genomic structural instability in the region. © 2011 Wiley-Liss, Inc.

Genomic strategy identifies a missense mutation in WD-repeat domain 65 (WDR65) in an individual with Van der Woude syndrome.

Genetic variation in the transcription factor interferon regulatory factor 6 (IRF6) causes and contributes risk for oral clefting disorders. We hypothesized that genes regulated by IRF6 are also involved in oral clefting disorders. We used five criteria to identify potential IRF6 target genes; differential gene expression in skin taken from wild-type and Irf6-deficient murine embryos, localization to the Van der Woude syndrome 2 (VWS2) locus at 1p36-1p32, overlapping expression with Irf6, presence of a conserved predicted-binding site in the promoter region, and a mutant murine phenotype that was similar to the Irf6 mutant mouse. Previously, we observed altered expression for 573 genes; 13 were located in the murine region syntenic to the VWS2 locus. Two of these genes, Wdr65 and Stratifin, met 4 of 5 criteria. Wdr65 was a novel gene that encoded a predicted protein of 1,250 amino acids with two WD domains. As potential targets for Irf6 regulation, we hypothesized that disease-causing mutations will be found in WDR65 and Stratifin in individuals with VWS or VWS-like syndromes. We identified a potentially etiologic missense mutation in WDR65 in a person with VWS who does not have an exonic mutation in IRF6. The expression and mutation data were consistent with the hypothesis that WDR65 was a novel gene involved in oral clefting.

Interparietal bone (Os Incae) in craniosynostosis.

The interparietal bone, Os Incae, is formed in a persistent mendosal suture. This suture is a normal variant in the human skull, well-known in anatomy and radiology textbooks. We report 11 children with craniosynostosis in the presence of an interparietal bone, five from Children's Hospital at Montefiore and six children from Children's Hospital Boston. The true incidence of an interparietal bone in patients with craniosynostosis or craniofacial anomalies is not known; nor are there recognized sequelae of an interparietal bone (bathrocephaly). Hypotheses regarding mechanisms that may contribute to the formation of an interparietal bone are discussed.

Minimal evidence for a direct involvement of twisted gastrulation homolog 1 (TWSG1) gene in human holoprosencephaly.

Holoprosencephaly (HPE) is the most common disorder of human forebrain and facial development. Presently understood etiologies include both genetic and environmental factors, acting either alone, or more likely, in combination. The majority of patients without overt chromosomal abnormalities or recognizable associated syndromes have unidentified etiologies. A potential candidate gene, Twisted Gastrulation Homolog 1 (TWSG1), was previously suggested as a contributor to the complex genetics of human HPE based on (1) cytogenetic studies of patients with 18p deletions, (2) animal studies of TWSG1 deficient mice, and (3) the relationship of TWSG1 to bone morphogenetic protein (BMP) signaling, which modulates the primary pathway implicated in HPE, Sonic Hedgehog (SHH) signaling. Here we present the first analysis of a large cohort of patients with HPE for coding sequence variations in TWSG1. We also performed fine mapping of 18p for a subset of patients with partial 18p deletions. Surprisingly, minimal evidence for alterations of TWSG1 was found, suggesting that sequence alterations of TWSG1 are neither a common direct cause nor a frequent modifying factor for human HPE pathologies.

Introductory comments on special section-new developments in craniofacial biology: putting on a happy face.

Approximately three quarters of children with birth defects have anomalies that affect the craniofacial structures. Defects in this area of the body result in lifelong disability, major challenges to families and society and often a serious effect on life expectancy. Surgery has been the primary intervention for these disorders, with frequently less than optimal outcomes and risk for additional morbidity and mortality. The challenge for clinicians caring for these children is to develop new methods for the treatment and prevention of these disorders. An understanding of the evolution of the head and the finely tuned temporospatial signaling pathways involved is critical to understanding the origins of the vertebrates as well as of human craniofacial malformations. In the future, these new approaches will be based upon our enhanced understanding of the developmental tool kit fashioned by evolution and the application of this knowledge toward the development of new diagnostic, pharmacologic, and genetic interventions for these disorders.

Mutational analysis of HOXA2 and SIX2 in a Bronx population with isolated microtia.

OBJECTIVE: Microtia is a developmental malformation of the external ear with genetic and environmental causes. The prevalence of microtia varies but several studies suggest increased incidence in Hispanic and African American populations. No causal genetic mutations have been identified in these populations. Mutations in the homeobox gene HOXA2 caused microtia in a single Iranian family. Another homeobox gene, SIX2, acts downstream of HOXA2 during development and provides another possible candidate for mutational analysis. METHODS: To determine whether mutations in HOXA2 or SIX2 cause sporadic microtia, DNA sequencing analysis was performed on exons in both genes in 8 patients of Hispanic and African descent in the Bronx. Identified variants were assayed in an additional 4 patients and 100 Hispanic control samples using Sequenom MassArray to rule out causality in heterozygous patients. RESULTS: No mutations were identified in the coding sequence of HOXA2 or SIX2. Four novel single nucleotide variants were identified among the patient samples. These variants lie in the intron and 3' UTR of HOXA2 and the 5' and 3' UTRs of SIX2. One variant in the intron of HOXA2 lies in a conserved predicted transcription factor binding site for SMARCA3. All four variants are also present at >5% frequency in Hispanic control samples, ruling out these novel variations as causal. CONCLUSIONS: Lack of mutations in the coding regions of HOXA2 or SIX2 among the sporadic microtia patients studied indicate different etiologies. Identification of four novel single nucleotide polymorphisms in patients and controls of Hispanic descent, but not of Caucasian populations, points to genetic diversity in an understudied population.

Cervical vascular and upper airway asymmetry in Velo-cardio-facial syndrome: correlation of nasopharyngoscopy with MRA.

PURPOSE: Velo-cardio-facial syndrome (VCFS), the most common genetic syndrome causing cleft palate, is associated with internal carotid and vertebral artery anomalies, as well as upper airway asymmetry. Medially displaced internal carotid arteries, often immediately submucosal, present a risk of vascular injury during pharyngeal flap surgery for velopharyngeal insufficiency (VPI). We evaluate the frequency and spectrum of cervical vascular anomalies in a large cohort of VCFS patients correlating MRA with nasopharyngolaryngoscopy in detecting at risk carotid arteries. Furthermore, we assess the relationship with respect to laterality between cervical vascular patterns and the asymmetric abnormalities of these subjects' upper airways. METHODS: Cervical MRAs of 86 subjects with VCFS and 50 control subjects were independently reviewed by three neuroradiologists. The course of the internal carotid and vertebral arteries was identified within the pharyngeal soft tissues. Medial deviation, level of bifurcation, dominance, anomalous origin, and vessel tortuosity were recorded. Nasopharyngoscopy examinations were available for retrospective review in 43 patients and were assessed for palatal and posterior pharyngeal wall symmetry, true vocal cord motion and size, and for the presence or absence of carotid pulsations. The endoscopic findings were compared with MRA results. RESULTS: Of the 86 subjects, 80 (93%) had one or more vascular anomalies. 42 subjects (49%) were found to have medial deviation of at least one internal carotid artery. In 24 subjects (28%) the anomalous internal carotid artery was directly submucosal; four of these were bilateral (5% of the total sample, 17% of those with a submucosal internal carotid). Other carotid anomalies included low carotid bifurcation (44 subjects or 51%), anomalous origin of the right common carotid (32 cases, or 37%), and two cases of internal carotid agenesis/hypoplasia. Vertebral artery anomalies included vessel tortuosity (34 cases, or 40%), hypoplasia (10 cases, or 12%), looping (4 cases, or 5%), and one case of a double left vertebral artery. Though patients in our study showed an asymmetric distribution of vascular anomalies, no association was found between the laterality of palatal motion, pharyngeal fullness, or laryngeal movement and structure with ipsilateral vertebral or carotid artery anomalies. Of the 33 pulsatile carotid arteries visualized at nasopharyngoscopy, only nine were found to be submucosal on MRA. In contrast, 11 submucosal carotid arteries confirmed at MRA demonstrated no visible pulsations. Positive and negative predictive values of pulsative arteries seen endoscopically for MRA confirmation of a submucosal carotid course was 27% and 79% respectively. CONCLUSIONS: Carotid and vertebral artery anomalies are common in VCFS including marked medial deviation of the internal carotid artery in close proximity to the donor site for pharyngeal flap surgery. Lack of correlation between laterality of vascular anomalies and upper airway structural asymmetry in VCFS does not support the hypothesis that palatal, pharyngeal, and laryngeal anomalies are due to secondary developmental sequences caused by in utero vascular insufficiency. The presence or absence of carotid pulsations seen by nasopharyngoscopy does not correlate with the carotid arterial depth identified on MRA. Furthermore, identification of the relative medial-lateral retropharyngeal position of a submucosal carotid affords the opportunity to modify the surgical approach. These findings further support the routine use of pre-operative neck MRA in VCFS patients in surgical planning.

Joubert syndrome 2 (JBTS2) in Ashkenazi Jews is associated with a TMEM216 mutation.

Patients with Joubert syndrome 2 (JBTS2) suffer from a neurological disease manifested by psychomotor retardation, hypotonia, ataxia, nystagmus, and oculomotor apraxia and variably associated with dysmorphism, as well as retinal and renal involvement. Brain MRI results show cerebellar vermis hypoplasia and additional anomalies of the fourth ventricle, corpus callosum, and occipital cortex. The disease has previously been mapped to the centromeric region of chromosome 11. Using homozygosity mapping in 13 patients from eight Ashkenazi Jewish families, we identified a homozygous mutation, R12L, in the TMEM216 gene, in all affected individuals. Thirty individuals heterozygous for the mutation were detected among 2766 anonymous Ashkenazi Jews, indicating a carrier rate of 1:92. Given the small size of the TMEM216 gene relative to other JBTS genes, its sequence analysis is warranted in all JBTS patients, especially those who suffer from associated anomalies.

Clinical and molecular characterization of a patient with Langer-Giedion syndrome and mosaic del(8)(q22.3q24.13).

The tricho-rhino-phalangeal syndrome type II (TRPS II) is characterized by sparse scalp hair, a long nose with a bulbous tip, a long flat philtrum, cone-shaped epiphyses of the phalanges, retarded bone age in infancy and multiple cartilaginous exostoses. All patients have a hemizygous deletion on chromosome 8q23.3-24.11 which spans at least the 2.8 Mb-region from TRPS1 through EXT1. Only patients with deletions that extend beyond this interval tend to have mental retardation. Here we describe a 14.5-year-old girl with mental retardation and TRPS II. Her facial features are only mild, but she has the typical skeletal features including cone-shaped epiphyses at the phalanges, retarded bone age, multiple exostoses and short stature. She is the first patient with TRPS II and a molecularly proven mosaic interstitial deletion in 8q22.3-q24.13. The deletion is one of the largest ever found in TRPS II, and spans 19.79 Mb and 50 genes or loci including TRPS1 and EXT1. The degree of mosaicism is 7% in lymphocytes from peripheral blood and 97% in skin fibroblasts.

Holoprosencephaly-Polydactyly syndrome: in search of an etiology.

Holoprosencephaly-Polydactyly (HPS) or Pseudotrisomy 13 syndrome are names conferred to clinically categorize patients whose phenotype is congruent with Trisomy 13 in the context of a normal karyotype. The literature suggests that this entity may be secondary to submicroscopic deletions in holoprosencephaly (HPE) genes; however, a limited number of investigations have been undertaken to evaluate this hypothesis. To test this hypothesis we studied a patient with HPE, polydactyly, and craniofacial dysmorphologies consistent with the diagnosis of Trisomy 13 whose karyotype was normal. We performed mutational analysis in the four main HPE causing genes (SHH, SIX3, TGIF, and ZIC2) and GLI3, a gene associated with polydactyly as well as fluorescent in situ hybridization (FISH) to search for microdeletions in these genes and two candidate HPE genes (DISP1 and FOXA2). No mutations or deletions were detected. A whole genome approach utilizing array Comparative Genomic Hybridization (aCGH) to screen for copy number abnormalities was then taken. No loss or gain of DNA was noted. Although a single case, our results suggest that coding mutations in these HPE genes and copy number anomalies may not be causative in this disorder. Instead, HPS likely involves mutations in other genes integral in embryonic development of the forebrain, face and limbs. Our systematic analysis sets the framework to study other affected children and delineate the molecular etiology of this disorder.

Muenke syndrome (FGFR3-related craniosynostosis): expansion of the phenotype and review of the literature.

Muenke syndrome is an autosomal dominant disorder characterized by coronal suture craniosynostosis, hearing loss, developmental delay, carpal and tarsal fusions, and the presence of the Pro250Arg mutation in the FGFR3 gene. Reduced penetrance and variable expressivity contribute to the wide spectrum of clinical findings in Muenke syndrome. To better define the clinical features of this syndrome, we initiated a study of the natural history of Muenke syndrome. To date, we have conducted a standardized evaluation of nine patients with a confirmed Pro250Arg mutation in FGFR3. We reviewed audiograms from an additional 13 patients with Muenke syndrome. A majority of the patients (95%) demonstrated a mild-to-moderate, low frequency sensorineural hearing loss. This pattern of hearing loss was not previously recognized as characteristic of Muenke syndrome. We also report on feeding and swallowing difficulties in children with Muenke syndrome. Combining 312 reported cases of Muenke syndrome with data from the nine NIH patients, we found that females with the Pro250Arg mutation were significantly more likely to be reported with craniosynostosis than males (P < 0.01). Based on our findings, we propose that the clinical management should include audiometric and developmental assessment in addition to standard clinical care and appropriate genetic counseling.