Sclerocornea associated with the chromosome 22q11.2 deletion syndrome

Reported ocular findings in the 22q11.2 deletion syndrome (which encompasses the phenotypes of DiGeorge, velocardiofacial, and Takao (conotruncal-anomaly-face) syndromes) have included posterior embryotoxon (prominent, anteriorly displaced Schwalbe's line at the corneal limbus or edge), retinal vascular tortuosity, eyelid hooding, strabismus, and astigmatism. We present seven 22q11.2 patients from multiple centers with sclerocornea, an eye finding previously unreported in the literature. Four boys and three girls were identified with sclerocornea, systemic DGS/VCFS findings, and fluorescence in situ hybridization (FISH)-confirmed microdeletion at chromosome 22q11.2. FISH diagnosis was perinatal in six patients but at 2 years of age in one child. Sclerocornea was bilateral in five patients. Findings included descemetocele (five eyes), microophthalmos (one eye), iridocorneal adhesions (one bilateral case), and severe anterior segment dysgenesis (one eye). Two patients underwent bilateral corneal transplantation; another two were scheduled for possible unilateral transplant. Sclerocornea is a static congenital condition in which the cornea is opaque and vascularized and resembles the sclera. The novel finding of sclerocornea suggests that a genetic locus at 22q11.2 may be involved in anterior segment embryogenesis. In most of our patients, the diagnostic process was underway, but in one patient 22q11.2 deletion was not suspected until after the child had already been undergoing treatment for sclerocornea for 2 years. Sclerocornea should be added to the clinical manifestations of the 22q11.2 deletion syndrome. Ophthalmologists diagnosing sclerocornea in children with systemic findings suggestive of 22q11.2 deletion should ensure appropriate genetic referral.     

Vasomotor instability in neonates with chromosome 22q11 deletion syndrome

Approximately 70% of individuals with chromosome 22q11 deletion syndrome (22q11DS) have congenital heart defects. A host of other vascular problems in these patients, such as tortuous carotid arteries, Raynaud's phenomenon, unexplained hypotension, hypertension, and hypothermia, raise the possibility that there may be abnormal autonomic regulation of the vascular system. So far, however, there has been no formal report of autonomic dysfunction in patients with 22q11 deletion. We present two infants with 22q11DS, who had profound hypotension after uncomplicated surgeries for congenital heart disease. The hypotension was not responsive to vasopressor treatment (and extracorporeal membrane oxygenation in one infant) and resulted in death, due to multiorgan system failure. Obvious causes, such as poor cardiac contractility, prolonged circulatory arrest, neurological abnormality, sepsis and blood loss were excluded. On autopsy, no abnormalities were found that could explain the hypotension. We hypothesize that these infants died of severe hypotension due to abnormal vascular tone and that this is a variable feature in individuals with 22q11 deletion. The autonomic nervous system, which is responsible for the regulation of vasomotor tone, may be variably affected in 22q11DS. This could have implications for the surgical management of patients with 22q11DS. Further studies on this topic would establish or refute the association between 22q11DS and dysautonomia.     

Radial aplasia and chromosome 22q11 deletion.

We report on a neonate with deletion 22q11 (del22q11) presenting with facial dysmorphism, ocular coloboma, congenital heart defect, urogenital malformations, and unilateral radial aplasia. This malformation complex includes features frequently occurring in velocardiofacial syndrome as well as findings described in the CHARGE and VACTERL associations. To our knowledge, the present case is the first report of radial aplasia in del22q11. This observation further supports and extends the clinical variability of del22q11.     

Prenatal diagnosis of tetralogy of Fallot associated with chromosome 22q11 deletion

Microdeletion of 22q11 is responsible for DiGeorge syndrome, velocardiofacial syndrome, congenital conotruncal heart defects, and related disorders. We report our experiences on prenatal diagnosis by fluorescence in situ hybridization (FISH) for 22q11 deletion in two fetuses with tetralogy of Fallot. Karyotyping and FISH of the parents revealed that one fetus inherited the disease from maternal microdeletion. These findings suggest the importance of performing FISH in pregnancies with prenatally detected tetralogy of Fallot.     

Kousseff syndrome caused by deletion of chromosome 22q11-13

Kousseff syndrome was originally described by Boris Kousseff in 1984: Pediatrics 74:395-398 in three siblings whose main features were conotruncal heart defects, neural tube defects, and dysmorphic features. The proband is a white male who has spina bifida, shunted hydrocephalus, cleft palate, short stature, cognitive impairment, and the typical craniofacial features of velo-cardio-facial syndrome (VCFS), including low-set and dysplastic ears, broad base of the nose, narrow alae nasi, and retrognathia. The family history is significant for a brother who died at 2 weeks of age with myelomeningocele, hydrocephalus, transposition of the great vessels, and unilateral renal agenesis, and a sister who died at 11 days of age with myelomeningocele, truncus arteriosus, hypocalcemia, and autopsy findings of absent thymus and parathyroid glands, consistent with DiGeorge anomaly. Given the clinical findings, family history, and recent knowledge that open neural tube defects can occur in VCFS/DiGeorge anomaly, FISH analysis for 22q11-13 deletion was performed on the proband. A deletion was detected in him and subsequently confirmed in his father. Molecular analysis on autopsy material confirmed the deletion in the proband's deceased brother. We suggest that individuals with neural tube defects associated with other anomalies such as congenital heart defects or cleft palate be evaluated for 22q deletions.     

Monozygotic twins with chromosome 22q11 deletion and discordant phenotype.

We report monozygotic twins concordant for 22q11.2 deletion but discordant for clinical phenotype. Both boys show the typical dysmorphic features with short palpebral fissures, square nasal tip, small mouth, and both have nasal speech, but only one twin had a heart defect. They show that the phenotypic variability seen in this microdeletion syndrome cannot be explained on the basis of genotypic differences alone.     

Pulmonary atresia associated with maternal 22q11.2 deletion: possible parent of origin effect in the conotruncal anomaly face syndrome.

A blind study was designed to test the hypothesis that some persons with a relatively rare cardiac malformation, pulmonary atresia with ventriculoseptal defect (PA/VSD), have a recognisable phenotype. Fourteen patients with cyanotic congenital heart lesions were examined by dysmorphologists blinded to the type of cardiac malformation. Six children were judged to have a similar craniofacial appearance; all had PA/VSD. These children were not originally considered to fall within the classic phenotypes of the DiGeorge sequence or the velocardiofacial syndrome, both of which have been shown to be associated with deletions of 22q11. More recently, 22q11 deletions have been documented in the conotruncal anomaly face syndrome and apparently isolated conotruncal heart defects. A new acronym, CATCH 22 syndrome (Cardiac defects, Abnormal facies, Thymic hypoplasia, Cleft palate, and Hypocalcaemia) has been suggested to encompass this very broad phenotypic spectrum. A preliminary molecular study was conducted using the dinucleotide repeat D22S264 located on chromosome 22q11.2. All cases tested with the subtle but recognisable phenotype had deletions, all lacking the maternal contribution at this locus, suggesting there may be a parent of origin effect.     

Confirmation that the velo-cardio-facial syndrome is associated with haplo-insufficiency of genes at chromosome 22q11

The velo-carido-facial syndrome (VCFS) and DiGeorge sequence (DGS) have many similar phenotypic characteristics, suggesting that in some cases they share a common cause. DGS is known to be associated with monosomy for a region of chromosome 22q11, and DNA probes have been shown to detect these deletions even in patients with apparently normal chromosomes. Twelve patients with VCFS were examined and monsomy for a region of 22q11 was found in all patients. The DNA probes used in this study could not distinguish the VCFS locus and the DGS locus, indicating that the genes involved in these haplo-insufficiencies are closely linked, and may be identical. The phenotypic variation of expression in VCFS and DGS may indicate that patients without the full spectrum of VCFS abnormalities but with some manifestations of the disorder may also have 22q11 deletions. © 1993 Wiley-Liss, Inc.     

An unusual chromosome 22q11 deletion associated with an apparent complementary ring chromosome in a phenotypically normal woman

We report an unusual chromosome 22q11 deletion associated with an apparent complementary ring chromosome in a phenotypically normal woman with a family medical history of 22q11 deletion. Using peripheral blood samples, conventional karyotyping, Fluorescence In Situ Hybridization (FISH) analysis on metaphase spreads and oligo array-based comparative genomic hybridization (oligo array-CGH) were performed. After conventional cytogenetic examination, the chromosome formula was as follows: 47,XX,+r(?)[16]/46,XX[6]. The FISH analysis revealed that this patient had a rearranged chromosome 22 with decreased centromeric fluorescence intensity and deletion of the 22q11.2 locus. She also had a supernumerary ring chromosome composed of an alpha-satellite centromere of 22 origin and 22q11.2 locus. The oligo array-CGH profile showed a deletion of approximately 4.18?Mb on chromosome 22 with a log 2 intensity ratio mean deviation of the deleted region of about -0.29. The 22q11 deletion associated with a complementary ring chromosome described in our patient could be consistent with a centromere misdivision mechanism, with one chromosomal break occurring in the alpha-satellite array and a second one in the 22q11 locus, a mechanism which has recently been referred to as the McClintock mechanism.     

Cortical dysgenesis in 2 patients with chromosome 22q11 deletion

Two patients with chromosome 22q11 deletion and cortical dysgenesis (gyral abnormalities) are reported in this study. One had unilateral clubfoot in addition to multiple features suggestive of the Di George syndrome (DGS), and the other presented with leg asymmetry and seizures, with subsequent recognition of the velo-cardio-facial syndrome (VCFS). In each patient, gyral abnormalities were identified in the hemisphere contralateral to the limb abnormality. A wide range of central nervous system abnormalities have been reported in DGS and VCFS, including three prior reports of gyral abnormalities (lissencephaly, microgyria). The 2 patients reported herein strengthen the association between the 22q11 deletion spectrum and cortical dysgenesis, but the underlying pathogenetic mechanism (primary neural migration vs. vascular disruption) remains unclear.     

Constitutional 11q14-q22 chromosome deletion syndrome in a child with neuroblastoma MYCN single copy

Constitutional 11q deletion is a chromosome imbalance possibly found in MCA/MR patients analyzed for chromosomal anomalies. Its role in determining the phenotype depends on extension and position of deleted region. Loss of heterozygosity of 11q (region 11q23) is also associated with neuroblastoma, the most frequent extra cranial cancer in children. It represents one of the most frequent cytogenetic abnormalities observed in the tumor of patients with high-risk disease even if germline deletion of 11q in neuroblastoma is rare. Hereby, we describe a 18 months old girl presenting with trigonocephaly and dysmorphic facial features, including hypotelorism, broad depressed nasal bridge, micrognathia, synophrys, epicanthal folds, and with a stage 4 neuroblastoma without MYCN amplification, carrying a germline 11q deletion (11q14.1-q22.3), outside from Jacobsen syndrome and from neuroblastoma 11q critical regions. The role of 11q deletion in determining the clinical phenotype and its association with neuroblastoma development in the patient are discussed.     

Interstitial deletion of chromosome 16q: 16q22 is critical for 16q- syndrome.

Partial deletion of 16q is rare; to our knowledge only 12 cases have been published. Fryns et al. [Hum Genet 38:343-346, 1977] described the first of these cases and proposed a new clinical entity. Our patient was a girl and had many minor anomalies of the kind often observed in 16q- syndrome. Severe failure to thrive due to emesis and diarrhea were also observed. High resolution banding methods showed that the chromosome constitution of the patient was 46,XX,del(16)(q22.1q22.3). This suggests that 16q22 is critical for the syndrome.