Monosomy of chromosome No. 22. A case report

Compound phenotype in a girl with r(22), concomitant microdeletion 22q13.32-q13.33 and mosaic monosomy 22

Background

Ring chromosome instability may influence a patient's phenotype and challenge its interpretation.

Results

Here, we report a 4-year-old girl with a compound phenotype. Cytogenetic analysis revealed her karyotype to be 46,XX,r(22). aCGH identified a 180 kb 22q13.32 duplication, a de novo 2.024 Mb subtelomeric 22q13.32-q13.33 deletion, which is associated with Phelan-McDermid syndrome, and a maternal single gene 382-kb TUSC7 deletion of uncertain clinical significance located in the region of the 3q13.31 deletion syndrome. All chromosomal aberrations were confirmed by real-time PCR in lymphocytes and detected in skin fibroblasts. The deletions were also found in the buccal epithelium. According to FISH analysis, 8% and 24% of the patient's lymphocytes and skin fibroblasts, respectively, had monosomy 22.

Conclusions

We believe that a combination of 22q13.32-q13.33 deletion and monosomy 22 in a portion of cells can better define the clinical phenotype of the patient. Importantly, the in vivo presence of monosomic cells indicates ring chromosome instability, which may favor karyotype correction that is significant for the development of chromosomal therapy protocols.

Abnormal abdominal situs: what and how should we look for?

BACKGROUND

Prenatal management of abnormal abdominal situs is challenging since prognosis is highly variable depending on the associated malformations.

METHODS

The authors report on two cases of ambiguous abdominal situs. Prenatal management included specialized ultrasound examination of fetal anatomy and heart, amniocentesis for determination of the fetal karyotype and fetal abdominal MR.

RESULTS

In both cases, abnormal situs was associated with other abdominal anomalies such as azygous continuation, biliary atresia, bowel obstruction and polysplenia. Fetal MR was a useful additional tool in the assessment of fetal abdominal anatomy in both cases.

CONCLUSIONS

On the basis of these reports, the literature is reviewed and a prenatal management scheme is proposed.

Heterotaxy: associated conditions and hospital-based prevalence in newborns

PURPOSE

To provide insight into the possible etiology and prevalence of heterotaxy, we studied conditions associated with heterotaxy in a consecutive hospital population of newborns.

METHODS

From 1972 to March, 1999 (except February 16, 1972 to December 31, 1978), 58 cases of heterotaxy were ascertained from a cohort of 201,084 births in the ongoing Active Malformation Surveillance Program at the Brigham and Women's Hospital. This registry includes livebirths, stillbirths, and elective abortions. Prevalence among nontransfers (i.e., patients whose mothers had planned delivery at this hospital) was calculated as approximately 1 per 10,000 total births (20 of 201,084).

RESULTS

We analyzed a total of 58 patients consisting of 20 (34%) nontransfers and 38 (66%) transfers. Patients were categorized by spleen status as having asplenia (7 nontransfers, 25 total), polysplenia (8, 20), right spleen (4, 11), normal left (0, 1), and unknown (1, 0). Among the 20 nontransfer and 59 total heterotaxy patients, the following associated medical conditions were present: chromosome abnormality (1 nontransfer, 2 total), suspected Mendelian or chromosome microdeletion disorder (1 nontransfer, 6 total), and maternal insulin-dependent diabetes mellitus (1 nontransfer, 2 total). There were 6 twins (1 member each from 6 twin pairs including 1 dizygous, 4 monozygous, 1 conjoined; 2 were nontransfers). An associated condition occurred in 5 (25%) nontransfer and 16 (28%) total patients, or among 10 of 53 singleton births (19%).

CONCLUSIONS

Although most cases of heterotaxy in this series were sporadic events, an associated condition was present in about one-fourth of the cases. Not all of these conditions would be considered causative etiologies. Based on this small series alone, maternal insulin-dependent diabetes cannot be viewed as a risk factor for heterotaxy. However, the specific association of diabetes with polysplenia with/without left atrial isomerism is noteworthy, and adds weight to animal and epidemiologic case-control data.

Full mosaic monosomy 22 in a child with DiGeorge syndrome facial appearance

We describe an abnormal premature male infant with mosaic monosomy of chromosome 22. He had a unique facial appearance, similar to those with DiGeorge syndrome, and hypertonicity, limitation of extension at major joints, and flexion contractures of all fingers. This rare chromosomal aberration has been reported previously in 6 cases, three of them being nonmosaic and three mosaic patients. There was a great variability of expression among the anomalies of these patients. However, the most common anomalies were in the face and joints. A correlation between the severity of expression and percent of monosomic cells was not clear.

Defects in the determination of left-right asymmetry

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Digeorge syndrome with total monosomy 22 diagnosed prenatally

A case of monosomy 22 diagnosed prenatally is reported. During pregnancy, ultrasonic observations already revealed several cardiac malformations of the fetus in the 25th week. Following counselling, the pregnancy was terminated. Fetal autopsy revealed several abnormalities associated with DiGeorge syndrome.

Molecular genetic approaches to the study of human craniofacial dysmorphologies

Craniofacial dysmorphologies are common, ranging from simple facial disfigurement to complex malformations involving the whole head. With the advent of gene mapping and cloning techniques, the genetic element of both simple and complex human craniofacial dysmorphologies can be investigated. For many of the dysmorphic syndromes, it is possible to find families that display a particular phenotype in either an autosomal dominant, recessive, or X-linked manner. This article focuses on a subgroup of craniofacial dysmorphologies, covering these three main inheritance patterns, that are being studied using molecular biology techniques: DiGeorge syndrome, Treacher Collins syndrome, Greig cephalopolysyndactyly syndrome, acrocallosal syndrome, amelogenesis imperfecta, and X-linked cleft palate with ankyloglossia. Once the mutated or deleted gene or genes for each syndrome have been cloned, patterns of normal and abnormal craniofacial development should be elucidated. This should enhance both diagnosis and treatment of these common and disfiguring disorders.

Extrahepatic biliary atresia and associated anomalies: etiologic heterogeneity suggested by distinctive patterns of associations

Fifty-one cases of extrahepatic biliary atresia (EHBA) with associated anomalies were found in a study of EHBA (251 cases). Analysis of segregation patterns of these anomalies in individual patients suggested the existence of 2 major groups: (1) 15 cases (29.4%) with various combinations of anomalies within the laterality sequence, and (2) 30 cases (58.8%) with one or 2 anomalies mostly involving the cardiac, gastrointestinal, and urinary systems. These latter anomalies did not follow any recognizable pattern. The third group of 6 cases all had intestinal malrotation, some with preduodenal portal vein; these cases show some similarity to the laterality sequence group and may represent a more confined phenotypic result of faulty situs determination. This previously unattempted classification of patients with EHBA and associated anomalies might enable a more targeted approach towards identification of causes in this heterogeneous disorder. EHBA within the laterality sequence might prove a suitable candidate for a major gene mutation. Teratogenic, infectious and polygenic multifactorial causes might play a more significant role in EHBA associated with "nonsyndromic" organ system anomalies.

Di George anomaly associated with a de novo Y;22 translocation resulting in monosomy del(22)(q11.2)

We report on an infant, born to a diabetic mother, who presented with hypocalcemia and congenital heart disease, presurgically diagnosed by echocardiography as truncus arteriosus type I. Cytogenetic analysis showed a 45,X,-Y,-22,+der-(Y)t(Y;22) (p11.3q11.2) chromosome abnormality with del(22)(q11.2). Parental chromosomes were normal. Autopsy showed persistent truncus arteriosus type II and thymic aplasia consistent with DiGeorge anomaly. This report adds to the existing literature demonstrating an association between DiGeorge anomaly and monosomy 22q11.

Aortic root dilatation associated with partial trisomy 7(q31.2----qter)

Aortic root dilatation and mitral valve prolapse are cardiac findings sometimes seen in disorders of connective tissue, most often in the Marfan syndrome. This report describes an infant with these cardiac anomalies and a specific chromosomal abnormality, partial trisomy of chromosome 7 associated with partial monosomy of chromosome 22. This association may have significance with respect to the etiology of cardiac disease in connective tissue disorders such as Marfan syndrome.

Human chromosome 22

The acrocentric chromosome 22, one of the shortest human chromosomes, carries about 52 000 kb of DNA. The short arm is made up essentially of heterochromatin and, as in other acrocentric chromosomes, it contains ribosomal RNA genes. Ten identified genes have been assigned to the long arm, of which four have already been cloned and documented (the cluster of lambda immunoglobulin genes, myoglobin, the proto-oncogene c-sis, bcr). In addition, about 10 anonymous DNA segments have been cloned from chromosome 22 specific DNA libraries. About a dozen diseases, including at least four different malignancies, are related to an inherited or acquired pathology of chromosome 22. They have been characterised at the phenotypic or chromosome level or both. In chronic myelogenous leukaemia, with the Ph1 chromosome, and Burkitt's lymphoma, with the t(8;22) variant translocation, the molecular pathology is being studied at the DNA level, bridging for the first time the gap between cytogenetics and molecular genetics.

The DiGeorge anomaly as a developmental field defect

The DiGeorge "syndrome" is a characteristic malformation pattern involving craniofacial, cardiac, thymic, and parathyroid structures. Evidence is accumulating that the DiGeorge "syndrome" is actually not a syndrome, but a polytopic developmental field defect. We present evidence of causal heterogeneity of the DiGeorge anomaly. This heterogeneity will be discussed in the light of recent findings that indicate that the dysmorphogenetically reactive unit responsible for the phenotype of the DiGeorge anomaly is a population of cephalic neural crest cells.

Familial third-fourth pharyngeal pouch syndrome with apparent autosomal dominant transmission

A family is presented in which both siblings and their father had evidence of third-fourth pharyngeal pouch syndrome (DiGeorge syndrome). All three individuals had hypocalcemia and unusual facies. Both infants had truncus arteriosus. One infant had evidence of impaired cell-mediated immunity; the father had a relatively decreased number of T-lymphocytes. The syndrome is uncommon, most cases being isolated, and familial presentations are even rarer. Two recent reports described several affected individuals who also had partial deletions of chromosome 22. Chromosome banding studies in our family were normal. Thus our family demonstrates an autosomal dominant pattern of inheritance, although it cannot be proved that this is a single gene defect. We propose that inasmuch as the presentation of the syndrome is quite varied, thorough family investigation including high-resolution cytogenetic analysis is necessary. Familial cases may be more common and require genetic counseling.

Monosomy 22 with humoral immunodeficiency: is there an immunoglobulin chain deficit?

The cytogenetic analysis of a patient with selective deficit of IgA and decrease in IgM, IgE, and IgG is presented. Using trypsin-Giemsa banding the karyotype showed monosomy 22 (45,XX,-22). The interest of this case lies in the rarity of the illness and in the association of monosomy 22 with hypogammaglobulinaemia and selective deficit of IgA, particularly as this chromosome is known to contain genes coding for immunoglobulin chains.

The association of the DiGeorge anomalad with partial monosomy of chromosome 22

We have seen three unrelated patients with the DiGeorge anomalad who also had the same deletion of chromosome 22 (pter leads to qll). In each, the remaining long arm material (qll leads to qter) was translocated to a different autosome. Our patients and a review of the literature, including a recent report of a family having four infants with the DiGeorge anomalad and the same deletion of chromosome 22 (de la Chapelle et al: Hum Genet 57:253, 1981), make a strong argument for at least some cases of the DiGeorge anomalad arising from a deletion of the pericentromeric region of chromosome 22.

A deletion in chromosome 22 can cause DiGeorge syndrome

An association between DiGeorge's syndrome and an unbalanced chromosomal rearrangement leading to trisomy 20pter leads to 20q11 and monosomy 22pter leads to 22q11 was found in four individuals belongings to one family. These and other data from the literature are interpreted to suggest that DiGeorge's syndrome can be caused by deletion of a gene located in chromosome 22, probably in band 22q11.

Monosomy 22 with mosaicism

A 2-year-old male child with mosaicism for monosomy of chromosome 22 is described. He had moderate psychomotor retardation, generalised hypotonia, large ears, epicanthus, synophrys, and cutaneous syndactyly between all the fingers.

Complex chromosomal rearrangement leading to partial trisomy 22

We have examined a boy with a peculiar facial appearance and mental retardation. Cytogenetic studies showed 47,XY, monosomy 22, two marker chromosomes, M1 and M2. The karotype is interpreted as functionally partial trisomy 22. Chromosome analyses of both parents and three sibs were normal.

Clinical and cytogenetic studies of two infants with partial monosomy G

Clinical and cytogenetic studies are reported in two infants with a stable ring G chromosome. Identification of the abnormal chromosomes was performed by the G-banding and the Q-banding methods.

A male infant with monosomy 21

A male infant with total monosomy 21 identified by Q-, G- and R-banding is described. His main symptoms are hypertonia, micrognathia, microphthalmus, imperforate anus, ambiguous external genitalia, floating and malopposed thumbs, overlying fingers, right clubfoot and growth retardation. Both parents are phenotypically as well as karotypically normal.

Segregation of a t(14q22q) chromosome in a large kindred

A large kindred is reported in which 21 members are balanced t(14q22q) carriers. The components of the translocation were identified by autoradiography and G-banding. With the exception of the index case, who was retarded, all of the carriers were phenotypically normal. The segregation pattern of the translocation chromosome was determined in two complete generations. All eight of the progeny in one generation were balanced carriers, and the carrier father of this generation may have been homozygous for the t(14q22q) chromosome. Segregation in the next generation was closer to the expected 1:1 ratio of carrier to non-carrier, the ratio being 11:13.

21 monosomy in a retarded female infant

A 20-month-old female infant with complete monosomy 21 is described. She has marked mental and physical retardation, antimongoloid slant, low set ears, micrognathia, syndactyly of the toes, and cardiac abnormalities. Karyotypes of fibroblasts and lymphocytes, examined with Giemsa banding, quinacrine banding, and reversed banding techniques revealed no evidence of translocation.