Cat-eye syndrome with different marker chromosomes in a mother and daughter

Identification of satellited markers by microdissection and fluorescence in situ hybridization: a clinical case of isodicentric chromosome 22

Background

The presence of small supernumerary marker chromosomes (sSMCs) in a karyotype leads to diagnostic questions because the resulting extra material may cause abnormal development depending on the origin of the duplication/triplication. Because SMCs are so small, their origin cannot be determined by conventional cytogenetic techniques, and new molecular cytogenetic methods are necessary. Here, we applied a target approach to chromosome rearrangement analysis by isolating a chromosome of interest via microdissection and using it in fluorescence in situ hybridization (FISH) as a probe in combination with whole-chromosome painting probes. This approach allows to identify origins of both the euchromatin and repeat-rich regions of a marker.

Case presentation

We report a case of an adult male with congenital atresia of the rectum and anus, anotia, and atresia of the external auditory canal along with hearing loss. Karyotyping and FISH analysis with whole-chromosome painting probes of acrocentric chromosomes and the constructed microdissection library of the marker chromosome reliably identified an additional chromosome in some metaphases: mos 47,XY,+idic(22)(q11.2)[14]/46,XY [23].

Conclusion

We propose to use whole-chromosome libraries and microdissected chromosomes in FISH to identify SMCs enriched with repeated sequences. We show that the methodology is successful in identifying the composition of a satellited marker chromosome.

Atypical presentation of Cat Eye Syndrome in an infant with Peters anomaly and microphthalmia with cyst

PURPOSE

To describe a unique ocular presentation of Cat Eye Syndrome and review the ocular and systemic findings associated with the syndrome.

METHODS

Case report with multimodal imaging.

RESULTS

A newborn female presented with a unilateral Peters anomaly with contralateral microphthalmia with cyst. The patient's other systemic findings included a hypoplastic right heart, persistent ductus arteriosus, intrauterine growth retardation, bilateral anotia, preauricular ear pits and skin tags, micrognathia, hypoplastic female genitalia, and unilateral cranial nerve VII palsy. Chromosomal microarray testing showed tetrasomy of chromosome 22 in the q11.1-q11.21 region consistent with Cat Eye Syndrome. The patient ultimately underwent a successful optical iridectomy on one side and orbitotomy with excision of the cystic mass on the other.

CONCLUSIONS

The co-occurrence of unilateral Peters anomaly with contralateral microphthalmia with cyst in Cat Eye Syndrome is rare and demonstrative of the syndrome's phenotypic variability. The medical and surgical management of these patients may require a multidisciplinary approach and must be tailored to the individual findings and overall systemic health of the patient.

Growth hormone deficiency and pituitary malformation in a recurrent Cat-Eye syndrome: a family report

Growth hormone deficiency affects roughly between one in 3000 and one in 4000 children with most instances of growth hormone deficiency being idiopathic. Growth hormone deficiency can also be associated with genetic diseases or chromosome abnormalities. Association of growth hormone deficiency together with hypothalamic-pituitary axis malformation and Cat-Eye syndrome is a very rare condition. We report a family with two brothers presenting with growth delay due to a growth hormone deficiency associated with a polymalformation syndrome. They both displayed pre-auricular pits and tags, imperforate anus and Duane retraction syndrome. Both parents and a third unaffected son displayed normal growth pattern. Cerebral MRI showed a hypothalamic-pituitary axis malformation in the two affected brothers. Cytogenetic studies revealed a type I small supernumerary marker chromosome derived from chromosome 22 resulting in a tetrasomy 22pter-22q11.21 characteristic of the Cat-Eye syndrome. The small supernumerary marker chromosome was present in the two affected sons and the mother in a mosaic state. Patients with short stature due to growth hormone deficiency should be evaluated for chromosomal abnormality. Family study should not be underestimated.

Coloboma and anorectal malformations: a rare association with important clinical implications

PURPOSE

In a patient with an anorectal malformation (ARM), the presence of a coloboma is commonly associated with other serious anomalies.

METHODS

Our database and the world literature were reviewed searching for associated defects in patients with ARM and coloboma.

RESULTS

Of 2,482 ARMs in our database, 11 had coloboma (0.4%): 2 were females. No specific associated type of ARM was identified. Six patients were developmentally delayed. Eight had a cardiac anomaly (3 had TAPVR, 2 VSD, 3 ASD), five required a cardiac operation. Five had a gastrointestinal anomaly (3 malrotation, 1 biliary and 1 duodenal atresia). Six had eye and seven had ear anomalies. Five had a genetic abnormality. In the literature, 71 patients with ARM and coloboma were found: 65 % were females. 24% died prematurely. 74% were developmentally delayed. 70% had a cardiac malformation (35% had TAPVR, 38% required an operation). 57% had gastrointestinal anomalies (31% malrotation, 31 % biliary atresia, 17% Hirschsprung disease). Eye and ear anomalies were present in 80 and 97% of patients, respectively. 81% had a genetic abnormality.

CONCLUSIONS

An ocular inspection in patients born with ARM is crucial. The finding of a coloboma should increase awareness to evaluate for a developmental, cardiologic or gastrointestinal anomaly.

A hereditary bisatellite-dicentric supernumerary chromosome in a case of cat-eye syndrome

We studied the clinical and cytogenetic features of a case of Cat-eye Syndrome. The chromosomal analysis showed 47 chromosomes. The supernumerary small, metacentric, bisatellited marker chromosome was probably derived from a No. 22 and occurred as well in the proband's sister and mother.

FISH approach to determine cat eye syndrome chromosome breakpoints of a patient with cat eye syndrome type II

We report a 19-year-old man with craniofacial dysmorphic features, anorectal malformations, eye colobomas, orthopaedic anomalies, and mild neurodevelopmental delay. Cat eye syndrome (CES) was suspected, and confirmed by cytogenetic analysis which showed the presence of a supernumerary bisatellited chromosome, identified by fluorescence in situ hybridization (FISH) as invdup(22). The marker was further analyzed with six BAC clones located at the 22q11.1 and 22q11.2 regions; this analysis allowed correct assignment at low copy repeat 4 on chromosome 22 (LCR22-4) of the two breakpoints, confirming the presence of a CES chromosome type II. The patient's phenotype is considered in the light of the cytogenetic, and FISH investigations results and other patients reported in literature. Molecular definition of the breakpoints at the LCR22-4 copy confirms the role of different chromosome 22-specific LCRs in CES chromosomes generation, as well as in other chromosome 22 germ line rearrangements. Our report confirms that, unlike other conditions, i.e. the invdup(15) bisatellited dicentric marker, the CES phenotype does not appear to correlate with the size of the marker chromosome. Additional cases are necessary to be able to draw more specific genotype-phenotype correlations and to determine the outcome of patients with CES, especially when this rare condition is diagnosed in prenatal age.

A molecular and FISH approach to determining karyotype and phenotype correlations in six patients with supernumerary marker(22) chromosomes

In a cytogenetic, molecular, and clinical study of patients with autosomal supernumerary marker chromosomes (SMC), 6 out of 72 (8.3%) were shown by fluorescence in situ hybridisation (FISH) to be derived from chromosome 22. PCR microsatellite analysis and FISH using primers and cosmids from proximal 22q showed 3 of the 6 to contain euchromatin. The first, a de novo nonmosaic bisatellited, dicentric SMC, was acsertained in a patient with cat eye syndrome and Duane anomaly. Microsatellite analysis showed the SMC was maternal in origin with euchromatin extending to D22S427, i.e., proximal to the DiGeorge syndrome critical region (DGSCR). The second, a nonmosaic bisatellited, dicentric marker, was found in a child with severe hypotonia and developmental delay and had been inherited from the patient's phenotypically normal father. FISH showed the SMC to contain euchromatin extending into the DGSCR. The third, a de novo SMC, was ascertained antenatally and was shown to contain 22q euchromatin extending distal to the DGSCR. The 19-week terminated fetus was phenotypically normal at autopsy. Two of the three SMC(22)s not containing detectable proximal 22q euchromatin were ascertained coincidentally in phenotypically normal individuals, whereas the third, the only mosaic with a minority euploid cell line, was found in a patient with mild developmental delay. These results suggest that SMC(22)s devoid of proximal 22q euchromatin are not associated with adverse phenotypic effects whereas SMC(22)s containing euchromatin may be found in individuals with phenotypes ranging from cat eye syndrome to normal.

Absence of lambda immunoglobulin sequences on the supernumerary chromosome of the "cat eye" syndrome

The supernumerary bisatellited chromosome causing the "cat eye" syndrome (CES) is of chromosome 22 origin and consists of an inverted duplication of the 22pter-->22q11.2 region. To determine the extent of involvement of band q11.2 on the bisatellited chromosome, copy number assessment of sequences homologous to cloned lambda immunoglobulin (lambda Ig) gene region probes was carried out on DNA from individuals with CES using densitometric analysis of Southern blots. None of the 10 lambda Ig sequences studied was found in increased copy number in DNA from any of the 10 CES individuals tested, indicating that these sequences are not present on the supernumerary chromosome. The breakpoints involved in the generation of the bisatellited supernumerary chromosome associated with CES are therefore proximal to the lambda Ig gene region.

Dynamic mosaicism involving an unstable supernumerary der(22) chromosome in cat eye syndrome

We have studied a girl, her sister and her mother who had a supernumerary marker chromosome in mosaicism. The marker was studied by cytogenetic methods and non-isotopic in situ hybridization with the single D22S9 DNA probe which maps to 22q11. The supernumerary chromosome was derived from a chromosome 22 and it did not present the same morphology in all the cells. At least 5 distinct types of the marker chromosome were detected and some of them were probably derived from each other (dynamic mosaicism). The proposita had an MCA pattern consistent with mild cat eye syndrome, while her sister and her mother had some of the manifestations described in this syndrome. A specific correlation could be established between phenotype and karyotype.

Association of familial Duane anomaly and urogenital abnormalities with a bisatellited marker derived from chromosome 22

We report a spectrum of defects that were found in an 18-year-old girl who presented for investigation of primary amenorrhea. The patient was found to have Duane anomaly, left renal agenesis, absent uterus, bilateral sensorineural deafness, and bilateral preauricular skin tags and sinuses. Investigation of her family showed that her brother also had Duane anomaly, right renal agenesis, sensorineural deafness, and preauricular skin tags and that their father had preauricular skin tags. Cytogenetic analysis, including in situ hybridisation of peripheral blood lymphocytes, demonstrated a supernumerary bisatellited marker chromosome derived from the region of chromosome 22pter-q11 in the affected individuals. Our findings indicate that a gene or genes located in the region of chromosome 22pter-q11 may be associated with the Duane anomaly and the development of the urogenital tract.

Molecular cytogenetic characterization of marker chromosomes found at prenatal diagnosis

The nature and origin of two de novo small marker chromosomes found at prenatal diagnosis were determined by fluorescence in situ hybridization using chromosome centromere-specific probes and chromosome-specific plasmid libraries. One marker was found in a mosaic state and was shown to be an i(18p). The second marker was characterized as an inv dup(22). We conclude that molecular cytogenetic analysis contributes to the identification of marker chromosomes and therefore facilitates genetic counselling and decision-making for the parents.

Typical and partial cat eye syndrome: identification of the marker chromosome by FISH

Three children are reported with typical cat eye syndrome (CES) and three more children with partial CES because of absence of coloboma, in which the supernumerary marker chromosome was studied by FISH. Using a genomic library, and also a centromeric and particularly a cosmid probe of 22q11, partial tetrasomy was shown in all cases.