Prenatal diagnosis by FISH of a 22q11 deletion in two families

OBJECTIVE: To investigate the predictive value of an intravenous fluid bolus during tilt table testing on clinical outcome and to evaluate of oral therapy is an effective treatment for patients with vasodepressor syncope. DESIGN: Retrospective cohort. SETTING: Regional pediatric cardiology outpatient clinic. PATIENTS: Patients (N = 58) with a positive baseline tilt table testing result who were treated with oral fluid therapy between February 1991 and March 1996. INTERVENTIONS AND MAIN OUTCOME MEASURES: Patients with a positive tilt table test result were given an intravenous bolus of isotonic saline solution. Responders were identified as having a negative tilt table test result after the bolus. Patients were prescribed a protocol of oral fluid therapy. Data were obtained from the medical record and a mailed survey. RESULTS: Of the 58 subjects, 90% had no recurrent syncope while receiving oral fluid therapy. During tilt table testing, the mean decrease in mean arterial pressure seen with symptomatic events was lower after the intravenous fluid. The heart rate, which dropped during the initial test, increased during the rests after the intravenous bolus. In the nonresponders, symptomatic episodes occurred significantly later in the tilt table test when given fluids. The response to intravenous fluid bolus had positive predictive value of 92% and negative predictive value of 11% of clinical outcome. CONCLUSIONS: Our data suggest that oral fluid therapy is an effective treatment for vasodepressor syncope in our population. Fluid bolus response during tilt table testing has a high positive but a low negative predictive value of response to oral fluid therapy. We now recommend oral fluid therapy as a primary intervention and reserve tilt table testing for oral fluid therapy failures.     

Increased incidence of renal anomalies in patients with chromosome 22q11 microdeletion

A 29-y-old male attempted suicide with 3000 mg clozapine, 150 mg zopiclone, alprazolam and unknown quantities of alcohol. He was admitted in a deep hypotonic coma with respiratory depression, inhalation pneumonia and vascular collapse. Symptomatic treatment involved mechanical ventilation, vascular filling and antibiotics. The patient was discharged from the Intensive Care Unit 72 h after the suicide attempt with no sequelae. To detect and quantify clozapine in plasma, high-pressure liquid chromatography showed a 4 h absorption phase and a peak serum concentration of 5200 ng/ml. Three successive elimination t1/2 values of 38, 24 and 13 h were calculated.     

Prevalence of the microdeletion 22q11 in newborn infants with congenital conotruncal cardiac anomalies

Conotruncal malformations account for about 50% of congenital heart defects diagnosed in newborns. We studied prospectively 104 patients admitted in our neonatal intensive care unit for conotruncal defects by fluorescence in situ hybridization to estimate the prevalence of the interstitial deletion in this category of congenital heart disease. Cardiac phenotypes were: truncus arteriosus (17), interrupted aortic arch (18), tetralogy of Fallot with or without pulmonary valve atresia (55), tetralogy of Fallot with absent pulmonary valves (5), ventricular septal defect with malalignment of the conal septum (9). We discovered a microdeletion 22q11 at loci D22S39 or D22S398 in 50 newborns (48%). The prevalence of this microdeletion in different groups of conotruncal defects was: truncus arteriosus 7/17, interrupted aortic arch 16/18, tetralogy of Fallot 19/55, absent pulmonary valves 2/5, and ventricular septal defect 6/9 respectively. Only two patients without any clinical or biological feature of the so called CATCH22 syndrome exhibited the deletion. Parental studies confirmed that the deletion occurred de novo in 47/50 cases (three parental microdeletions). On the other hand, recurrence of conotruncal heart defects in families of "undeleted probands" was higher than expected (13%). CONCLUSION: In 50/104 newborns with conotruncal defects, an interstitial deletion 22q11 was found. Fluorescence in Situ Hybridization should be performed in newborn infants with conotruncal defect and at least one additional manifestation of the CATCH22 phenotype.     

A novel 22q11.2 microdeletion in DiGeorge syndrome

BACKGROUND: Decreased red blood cell survival contributes to the anemia of chronic renal failure patients. Because patients on chronic dialysis therapy are frequently exposed to excessive complement activation, we investigated the susceptibility of this patient population to erythrocyte C5b-9 deposition, complement-mediated lysis, and ghost formation. METHODS: We developed a flow cytometric assay using antibodies to both glycophorin and the C5b-9 complex to detect C5b-9 deposition on intact erythrocytes and erythrocyte ghosts. Serum C5b-9 levels and C5b-9 deposition on erythrocyte ghosts were measured by enzyme-linked immunosorbent assay. RESULTS: A significant increase in C5b-9 deposition on intact erythrocytes was demonstrated in patients with advanced chronic renal failure (2.2 +/- 0.5%) and in patients on chronic maintenance hemodialysis (2.3 +/- 0.4%) compared with normal volunteers (0.9 +/- 0.1%, P = 0.005 vs. chronic renal failure, P < 0.001 vs. chronic hemodialysis patients). There was also a significantly higher percentage of C5b-9-positive erythrocyte ghosts in patients with advanced chronic renal failure (20.6 +/- 5%) and in chronic hemodialysis patients (15.5 +/- 3.1%) compared with normal controls (2.6 +/- 0.9%, P < or = 0.001 vs. advanced chronic renal failure and chronic hemodialysis patients). Treatment of erythrocyte preparations with cobra venom factor, which activates the complement cascade, resulted in dramatic increases in the percentages of C5b-9-positive erythrocyte ghosts in patients with chronic renal failure (49.9 +/- 6.9%) and in chronic hemodialysis patients (45.0 +/- 4.2%) compared with normal volunteers (22.3 +/- 2.7%, P < 0.001 vs. chronic renal failure and chronic hemodialysis patients). Erythrocyte membrane expression of the complement regulatory proteins CD59 and CD55 did not significantly differ between normal controls and hemodialysis patients. Plasma C5b-9 levels after cobra venom factor stimulation were higher in chronic renal failure patients (538 micrograms/ml) compared with normal controls (345 micrograms/ml, P < 0.001). CONCLUSIONS: Patients with chronic renal failure and on hemodialysis therapy are susceptible to erythrocyte C5b-9 deposition with subsequent lysis and ghost formation. Susceptibility to complement-mediated erythrocyte injury may contribute to the anemia of chronic renal disease.     

Deletion of chromosome 22q11 and pseudohypoparathyroidism

Multiple myeloma with IgG kappa monoclonal gammopathy and oliguric renal failure requiring hemodialysis was diagnosed in a 49-year-old man. Conventional therapy with VAD (vincristin, adriamycin, dexamethasone) failed to induce a complete response (CR) but this was subsequently obtained following two cycles of high-dose intravenous melphalan (70 mg/m2). A relapse occurred 8 months after CR which was treated by intensive myeloablative therapy combining total body irradiation (6 Gy over 2 days) and high-dose intravenous melphalan (140 mg/m2) followed by supportive PBSC transplantation. Hemodialysis was performed every other day during the myeloablative therapy and subsequent aplasia. Fluid subtraction allowed 1500 Cal/day intravenous alimentation and the only adverse event observed was a severe mucositis. A second CR was obtained which lasted 14 months. This observation indicates that multiple myeloma patients with end-stage renal failure can receive intensive myeloablative therapy without major toxicity.     

Isolation of NotI sites from chromosome 22q11

Chromosome 22q11 contains a large number of interesting loci, including genes associated with cancer and developmental defects. The region is also the site of the lambda immunoglobulin variable and constant regions and the BCR, gamma-glutamyl transpeptidase, and GGT-like activity multigene families. Because of the complexities associated with mapping highly related gene families, we have examined the utility of mapping large areas of DNA using a defined approach. A total of 21 complete NotI sites from band q11 were cloned and ordered into six noncontiguous clusters of sites using a combination of somatic cell hybrid panels, NotI jumping and linking libraries, and fluorescence in situ hybridization. The largest cluster spanned an estimated 2 Mb of NotI fragments, the smallest 115 kb. Approximately 3.5 Mb of band q11 could be examined for rearrangements in NotI restriction enzyme fragments. A number of conserved sequences, two genes, and a minimum of two families of related sequences were identified adjacent to NotI sites.     

Clinical implications and possible association of malposition of the branch pulmonary arteries with DiGeorge syndrome and microdeletion of chromosomal region 22q11

We describe a series of 10 patients with malposition of the branch pulmonary arteries (4 patients with crossing [crossed pulmonary arteries] and 6 patients without crossing), 2 of whom had a short main pulmonary artery segment that resulted in iatrogenic right pulmonary artery stenosis after pulmonary artery band placement. DiGeorge syndrome was seen in 5 patients and 4 had microscopic deletion of chromosomal region 22q11.     

Predisposition for breast cancer in carriers of constitutional translocation 11q;22q

A translocation between the long arms of chromosomes 11 and 22, t(11;22)(q23;q11), is the most frequent constitutional reciprocal translocation in man. This chromosome abnormality has not previously been reported to be associated with an increased risk for neoplasia. The observation of one patient with a constitutional translocation t(11q;22q) and breast cancer prompted us to study the relationship between these two conditions. The incidence of breast cancer was determined in carriers of t(11q;22q). The karyotypes were determined by QFQ-banding, and the breakpoints were then further characterized by fluorescent in situ hybridization. Eight families with a total of 22 balanced carriers were found. In five of these families there was one case of breast cancer each. In another family a case of an unknown malignancy was reported in one member. No other malignancies were found among these patients. The number of breast cancer cases was significantly higher than expected among the translocation carriers (P < .001). The chromosomal breakpoints showed the same localization with the markers used, in the seven families studied. The association of constitutional translocation t(11q;22q) and breast cancer identifies a subset of patients with a highly increased risk for breast cancer who would benefit from counseling and screening. It also suggests the involvement of genes on 11q and/or 22q, in the tumorigenesis of breast cancer.     

Aortic arch anomalies associated with chromosome 22q11 deletion (CATCH 22)

Subcutaneous infusion ports (SIPs) represent a valid method for long-term chemotherapy. The SIPs have several advantages over other methods of venous access: they are easy to implant under local anaesthesia, have less discomfort for the patients, allow low costs, can be implanted in day hospital, and can be managed ambulatorily. However, SIPs have delayed complications, frequently related to clinical conditions of the neoplastic patients, and immediate complications, often due to the placement technique. From March 1992 to March 1997 we placed, under local anaesthesia and under fluoroscopic control, 102 SIPs in 99 general oncology patients for long-term chemotherapy (88% solid, 12% haematological tumours). The percutaneous venous access devices were in the subclavian vein in 96% of the cases and in the internal jugular vein in 4% of them. Immediate complications were: 1 haemopneumothorax, which required thoracic aspirations and two blood transfusions, 1 loop of the tunneled part of the catheter without alterations in SIP function, and 1 left jugular thrombosis in a patient with subclavian veins already thrombosed. The venous access was in the subclavian vein in the first 2 cases, and it was not necessary to suspend the therapeutic program. In the third instance, implanted in jugular vein, it was necessary to remove the SIP. Delayed complications were: 1 necrosis of the skin over the port, 1 infection of subcutaneous pocket, 2 infections of the system, 1 catheter deconnection, and 3 catheter ruptures with embolization of the catheter tip. The SIPs were removed in all cases but 1 in whom infection was successfully treated by appropriate antibiotic therapy. Embolization of the catheter required removal from the pulmonary artery under fluoroscopic guidance in the cardiac catheterization laboratory. In conclusion, infection and thrombosis are the two major complications of SIP in general oncology patients. In these cases it is not necessary to remove systematically the system, but a correct therapy (antibiotic, fibrinolytic agents) can be utilized with good results. The catheter rupture is often due to the wear over the costoclavicular angle. The interventional radiology is the method of choice in the treatment of the catheter embolization by rupture or dislocation. The experience of the surgical and nursing staff is probably the most important factor in decreasing the total rate of complications.     

Prenatal diagnosis of fetal nuchal cystic hygroma in 22 cases

OBJECTIVE: To investigate the early diagnosis and prognosis of fetal nuchal cystic hygroma. METHODS: 72 cases of fetal nuchal cystic hygroma diagnosed in uterus were analyzed retrospectively. RESULTS: Most of the cases were diagnosed by B ultrasound between 15-26 gestational weeks. 55.9% the multipara had abnormal pregnant history, and 40% (4/10) of fetuses with karyotype performed had chrosome abnormality. Except for fetal deaths and induced abortions, 3 cases had term deliveries: one neonatal death, one was born with hygroma of 5.9 cm x 3.7 cm and transferred for surgery, and the other one with hygroma disappeared at the 37th week and baby was born at 40 week with normal appearance. CONCLUSIONS: This disease is one of common fetal morphological abnormalities. Few may recover spontaneously but most have poor outcomes.     

Familial deletions of chromosome 22q11: the Leuven experience

Renal medullary carcinoma is a recently described tumor that occurs exclusively in patients with sickle cell trait. Although extremely rare, the distinctive demographic, clinical, and radiologic findings should suggest the diagnosis of this aggressive neoplasm.     

Molecular definition of 22q11 deletions in 151 velo-cardio-facial syndrome patients

Velo-cardio-facial syndrome (VCFS) is a relatively common developmental disorder characterized by craniofacial anomalies and conotruncal heart defects. Many VCFS patients have hemizygous deletions for a part of 22q11, suggesting that haploinsufficiency in this region is responsible for its etiology. Because most cases of VCFS are sporadic, portions of 22q11 may be prone to rearrangement. To understand the molecular basis for chromosomal deletions, we defined the extent of the deletion, by genotyping 151 VCFS patients and performing haplotype analysis on 105, using 15 consecutive polymorphic markers in 22q11. We found that 83% had a deletion and >90% of these had a similar approximately 3 Mb deletion, suggesting that sequences flanking the common breakpoints are susceptible to rearrangement. We found no correlation between the presence or size of the deletion and the phenotype. To further define the chromosomal breakpoints among the VCFS patients, we developed somatic hybrid cell lines from a set of VCFS patients. An 11-kb resolution physical map of a 1,080-kb region that includes deletion breakpoints was constructed, incorporating genes and expressed sequence tags (ESTs) isolated by the hybridization selection method. The ordered markers were used to examine the two separated copies of chromosome 22 in the somatic hybrid cell lines. In some cases, we were able to map the chromosome breakpoints within a single cosmid. A 480-kb critical region for VCFS has been delineated, including the genes for GSCL, CTP, CLTD, HIRA, and TMVCF, as well as a number of novel ordered ESTs.     

Translocation (13; 18) (q22; p 11) and prenatal diagnosis (author's transl)

A balanced translocation (13; 18) (q 22; p 11) was diagnosed in two generations. Out of 10 pregnancies in these two translocation carriers, mother and daughter, only two phenotypically normal childern were born. One of these, namely the daughter, showed balanced translocation, whilst a normal karyotype was diagnosed prenatally in the second case. The other eight pregnancies ended either in spontaneous abortions, in intrauterine death or in lethal malformations. In the present translocation the formation of unbalanced gametes seems to be enhanced.     

Structural aberrations of the long arm of chromosome no. 22. Report fo a family with translocation t(11;22) (q25;q11)

A chromosomal translocation t(11;22) (q25q11) is described in a family. Four members, in two generations, had the same translocation but showed phenotypic variation. Case reports of chromosome aberrations involving the long arm of chromosome 22 associated with and without chronic myeloid leukemia (CML) are reviewed. It appears that the distal segment of the long arm or chromosome 22 is either translocated or deleted, resulting in congenital anomalies, presumably due to chromosome imbalance. In other instances, a specific breakpoint on 22q results in the origin of Philadelphia chromosome (Ph1) associated with CML.     

Congenital heart defects and 22q11 deletions: which genes count?

Hemizygous deletions on the long arm of chromosome 22 (del22q11) are a relatively common cause of congenital heart disease. For some specific heart defects such as interrupted aortic arch type B and tetralogy of Fallot with absent pulmonary valve, del22q11 is probably the most frequent genetic cause. Although extensive gene searches have been successful in discovering many novel genes in the deleted segment, standard positional cloning has so far failed to demonstrate a role for any of these genes in the disease. We show how the use of experimental animal models is beginning to provide an insight into the developmental role of some of these genes, while novel genome manipulation technologies promise to dissect the genetic aspects of this complex syndrome.     

Prenatal diagnosis

The enormous progress witnessed in the field of prenatal diagnosis during the past two decades is likely to continue into the future. Improved imaging techniques are likely to enhance the resolution of noninvasively obtained fetal images considerably over their current excellent quality. Although this undoubtedly will be true for ultrasonography, the increased speed of magnetic resonance equipment may offer a new realm of imaging possibilities. Computerized image processing, analysis, and three-dimensional reconstructions all should make interpretation of fetal images easier and more understandable to the nonspecialist. Advances in molecular genetics will continue to accelerate, greatly expanding the range and accuracy of prenatal diagnosis. The alert pediatrician who is sensitive to genetic issues may, by early detection of pediatric disorders and careful family history assessment, be in a position to identify families at risk for serious genetic conditions and provide the opportunity to make informed decisions on reproductive options that avert a major tragedy. The pediatrician, working with obstetric colleagues, should be part of a team effort to support families going through prenatal testing. Familiarity with these rapidly changing technologies will make it far easier to support the family needing additional explanation about prenatal diagnosis issues.     

Prenatal diagnosis of partial monosomy 13q associated with occipital encephalocoele in a fetus

The pre- and postnatal findings of a fetus with a de novo del(13)(pter-->q21:) and an occipital encephalocoele are described. Maternal serum alpha-fetoprotein (AFP) screening at 19 weeks' gestation demonstrated a high level of 2.5 multiples of the median (MOM) and ultrasonography at 27 weeks' gestation showed severe intrauterine growth retardation, cardiomegaly, an occipital encephalocoele, and a calvarial defect. Genetic amniocentesis revealed a karyotype of 46,XX,del(13)(pter-->q21:). The proband postnatally displayed additional abnormalities such as microphthalmia, hypertelorism, large low-set ears, and micrognathia. We discuss the association of central nervous system (CNS) malformations with 13q deletions and emphasize that pregnancies with neural tube defects warrant cytogenetic analysis, especially when additional fetal abnormalities and neonatal dysmorphism are observed.