1/187. Abdominal lymphatic dysplasia and 22q11 microdeletion. We report the case of a child with 22q11 microdeletion who presented with abdominal lymphatic dysplasia resulting in exsudative enteropathy. This primitive and localized lymphatic malformation is consistent with the vascular theory in the velocardiofacial syndrome. ( info) |
2/187. Possible extrathymic development of nonfunctional T cells in a patient with complete digeorge syndrome. Complete digeorge syndrome is characterized by the clinical triad of cardiac malformation, hypocalcemia, and T cell immunodeficiency due to congenital athymia. We describe an infant with complete digeorge syndrome who at presentation had no circulating T cells detectable by flow cytometry. The patient spontaneously developed circulating T cells but these cells did not proliferate in response to mitogens. The T cell receptor Vbeta repertoire was severely restricted. All T cells were host, not maternal, as assessed by fluorescent in situ hybridization evaluation of 22q11 hemizygosity. At autopsy, this patient had no grossly detectable thymus tissue and no microscopic evidence for thymopoiesis. These findings suggest that appearance of T cells in infants with complete digeorge syndrome may represent oligoclonal expansions of a small number of T cells that may have matured extrathymically and which do not respond in vitro to mitogen stimulation. ( info) |
| We describe 2 patients with a partial digeorge syndrome (facial dysmorphism, hypoparathyroidism, renal agenesis, mental retardation) and a rearrangement of chromosome 10p. The first patient carries a complex chromosomal rearrangement, with a reciprocal insertional translocation between the short arm of chromosome 10 and the long arm of chromosome 8, with karyotype 46, XY ins(8;10) (8pter 8q13::10p15-->10p14::8q24.1-->8qter) ins(10:8) (10pter--> 10p15::8q24.1-->8q13::10p14-->10qter). The karyotype of the second patient shows a terminal deletion of the short arm of chromosome 10. In both patients, the breakpoints on chromosome 10p reside outside the previously determined DiGeorge critical region II (DGCRII). This is in agreement with previous reports of patients with a terminal deletion of 10p with breakpoints distal to the DGCRII and renal malformations/hypoparathyroidism, and thus adds to evidence that these features may be caused by haploinsufficiency of one or more genes distal to the DGCRII. ( info) |
4/187. Patient with a 22q11.2 deletion with no overlap of the minimal digeorge syndrome critical region (MDGCR). The apparent lack of genotype/phenotype correlation in patients with the DiGeorge anomaly and velocardiofacial syndrome (DGA/VCFS; the "22q11 deletion syndrome") indicates a complex genetic condition. Most cases, whatever the phenotype, have a 1.5-3 Mb chromosomal deletion that includes the minimal DiGeorge critical region (MDGCR). Another potential critical region on 22q11 has been suggested based on two patients with distal deletions outside the MDGCR. We report on a patient with a VCFS phenotype who has a deletion, mapped by short tandem repeat polymorphic loci and fluorescence in situ hybridization analysis, distal to and not overlapping the MDGCR. This patient is deleted for several genes, including the T-box 1 gene (TBX1; a transcription regulator expressed early in embryogenesis) and catechol-O-methyltransferase (COMT; involved in neurotransmitter metabolism). We discuss the role these two genes may play in the clinical phenotype of the patient. ( info) |
5/187. B cell non-Hodgkin's lymphoma in a girl with the DiGeorge anomaly. The DiGeorge anomaly (DGA) is occasionally associated with cellular immunodeficiency. We report a female infant diagnosed with complete DGA, who developed fatal, high grade, non-Hodgkin's lymphoma that expressed Epstein-Barr virus (EBV). Non-Hodgkin's lymphoma should be considered in children with DGA. ( info) |
6/187. Interruption of the aortic arch at the isthmus with digeorge syndrome and 22q11.2 deletion. A 6-day-old male with interruption of the aortic arch at the isthmus (type A) had the typical phenotype of digeorge syndrome. There was also a doubly committed juxta-arterial ventricular septal defect and an unobstructed left ventricular outflow tract. Hypoplasia of the thymus was confirmed during a modified Blalock-Park operation. He had persistent hypocalcemia, and was susceptible to infection. He was subsequently revealed by the use of fluorescence in situ hybridization analysis to have 22q11.2 deletion. Interruption of the aortic arch at the isthmus is presumed to reflect abnormal fetal hemodynamics, and is considered a distinct pathogenetic entity from interruption between the left common carotid and subclavian arteries, the latter being the variant more frequently associated with digeorge syndrome. In our case, the 22q11.2 deletion likely played a major role in the etiology of the interrupted aortic arch. ( info) |
7/187. CATCH 22 syndrome: report of 7 infants with follow-up data and review of the recent advancements in the genetic knowledge of the locus 22q11. CATCH 22 is a medical acronym for Cardiac defects, Abnormal facies, Thymic hypoplasia, cleft palate, and hypocalcemia, and a variable deletion on chromosome 22. The deletion within the chromosome region of 22q11 may occur in patients with three well-described dysmorphologic cardiological syndromes: digeorge syndrome (DGS), velocardiofacial syndrome (VCFS), and conotruncal anomaly face syndrome (CTAFS). We report in detail seven infants with a deletion of the locus 22q11 showing overlapping clinical features of DGS and CTAFS with complex congenital heart defects (double outlet right ventricle, atresia or stenosis of the pulmonary valve, atrial and ventricular septal defects, patent ductus arteriosus, tetralogy of fallot, major aortopulmonary collateral arteries, arcus aortae dexter, and persistence of the left superior vena cava). A homograft was implanted between the right ventricle and the main stem of the pulmonary artery in 2 patients, while a balloon valvuloplastic of the pulmonary valve was performed in one patient only. Pulmonary hemorrhage, acute hypoxia, and aspergillus pneumonia were the complications. death occurred in three out of seven patients. Recent advancements in the genetic knowledge of the locus 22q11 are described. Since the locus 22q11 is highly heterogeneous, the CATCH 22 acronym should be used and temporarily the old eponyms should be abandoned waiting for the identification of the different genes. ( info) |
8/187. Atypical deletions suggest five 22q11.2 critical regions related to the DiGeorge/velo-cardio-facial syndrome. Deletions of chromosome 22q11.2 have been associated with distinct phenotypes including digeorge syndrome (DGS) and velo-cardio-facial (VCFS) syndrome. These diseases result from a failure to form derivatives of the third and fourth branchial arches during development. DGS/VCFS deletions usually encompass about 3 Mb of genomic dna in more than 90% of patients. However, deletion mapping studies have failed to demonstrate the existence of a single small region of overlap (SRO) and ruled out any obvious correlation between site or size of deletion and severity of clinical phenotype. We describe three patients carrying 'atypical' deletions presenting the DGS/VCFS phenotype. A comparative analysis of deletions in our patients and those previously published has suggested the existence of five distinct critical regions within the 22q11.2 locus. This observation argues that DGS/VCFS results from haploinsufficiency secondary to a complex and as yet unexplained molecular mechanism, probably involving chromatin effects in mediating gene expression throughout the entire region. ( info) |
| Partial monosomy 10p is a rare chromosomal condition and a significant proportion of patients show features of digeorge syndrome (DGS) and velocardiofacial syndrome (VCFS). A critical haploinsufficiency region for DGS/VCFS was defined on 10p (DGCR2). We performed molecular deletion analysis of two further patients with partial monosomy 10p, who showed hypoparathyroidism, deafness, and renal dysplasia or renal insufficiency, but no cardiac defect, cleft palate, or reduced T cell levels. Previously, the combination of hypoparathyroidism, deafness, and renal dysplasia has been proposed to represent a specific syndrome (MIM 146255) under the acronym HDR. In addition to the two patients in this report, at least four published cases with partial monosomy 10p show the triad of HDR and 14 other patients present with at least two of the three features. We therefore conclude that HDR syndrome can be associated with partial monosomy 10p. Based on molecular deletion analysis and the clinical data, we suggest that the DGS/VCFS phenotype associated with 10p deletion can be considered as a contiguous gene syndrome owing to haploinsufficiency of two different regions. Hemizygosity of the proximal region, designated DGCR2, can cause cardiac defect and T cell deficiency. Hemizygosity of the distal region, designated HDR1, can cause hypoparathyroidism and in addition sensorineuronal deafness and renal dysplasia/insufficiency or a subset of this triad. ( info) |
10/187. Oral findings in digeorge syndrome: clinical features and histologic study of primary teeth. OBJECTIVE: For the purpose of supplementing the shortage of dental information about digeorge syndrome, we report two cases of the syndrome seen in Japanese boys. STUDY DESIGN: Two cases were compared with respect to orofacial and dental findings; one was a case of complete digeorge syndrome and the other a case of partial digeorge syndrome. Extracted deciduous teeth from the two boys underwent histologic study. RESULTS: Each patient showed systemic developmental delay, hypocalcemia, and slight mental retardation. In the orofacial area, hypertelorism, a short philtrum, thick and reflected lips, and hypoplasia of the nasopharynx were also observed. A dental examination showed delayed formation and eruption of permanent teeth, aplasia of the nasopharynx, and enamel hypoplasia along with enamel hypocalcification. Structural streaks with increased calcification were histologically detected in the deciduous tooth from the patient with complete digeorge syndrome. CONCLUSIONS: Common characteristic orofacial and dental findings were noted in the two digeorge syndrome cases. Furthermore, histologic study of the deciduous tooth from the boy with complete digeorge syndrome suggests that there was some relationship between transient relative hypercalcemia and dentinal hypermineralized streaking of the tooth. ( info) |