Prenatal diagnosis of de novo terminal deletion of chromosome 7q

Clinical, cytogenetic, and molecular findings in a fetus with ultrasonic multiple malformations, 4q duplication, and 7q deletion: A case report and literature review

RATIONALE

Chromosome deletion/duplication has been reported to be associated with mental disability and dysmorphism according to the accumulated research evidence.

PATIENT CONCERNS

A 25-year-old woman underwent amniocentesis for cytogenetic and single-nucleotide polymorphism (SNP) array analysis at 18 weeks of gestation due to the increased Down syndrome risk of 1/13.

DIAGNOSES

The fetal chromosomal analysis revealed a seemingly "normal" chromosomal karyotype, but the SNP array results showed a partial duplication of chromosome 4q34.1q35.2 and a deletion of chromosome 7q34q36.3fluorescence in situ hybridization (FISH) analysis showed that the couple had normal chromosome 4 and 7, whereas there was a partial signal fragment of chromosome 4 attached on the long arm of chromosome 7 for the fetus.

INTERVENTIONS

The couple finally chose to terminate the pregnancy based on the ultrasonic multiple malformations and the abnormal SNP array results.

OUTCOMES

The duplicated/deleted segments of the fetus were de novo. Meanwhile, we consider SHH and XRCC2 as good candidate genes, which may, in part, explain the observed abnormalities for the fetus.

LESSONS

The combination of SNP array and FISH analysis can give a molecular chromosomal diagnosis, which will offer more clear cytogenetic diagnosis and genetic counseling.

Distal 3p duplication and terminal 7q deletion associated with nuchal edema and cyclopia in a fetus and a review of the literature

OBJECTIVE

To present perinatal detection of distal 3p duplication and terminal 7q deletion associated with nuchal edema and cyclopia in a fetus, and to review the literature.

MATERIALS AND METHODS

A 32-year-old, G9P0, woman who had experienced eight spontaneous abortions was found to have fetal nuchal edema, alobar holoprosencephaly, and cyclopia by prenatal ultrasound at 15 weeks of gestation. The pregnancy was subsequently terminated, and a malformed fetus was delivered with cyclopia. Molecular and conventional cytogenetic analyses were made to determine the genetic pathogenesis of fetal abnormalities.

RESULTS

The father had a karyotype of 46,XY,t(3;7)(p22.1;q36.1). The mother had a karyotype of 46,XX. The fetus had a karyotype of 46,XY,der(7)t(3;7)(p22.1;q36.1)pat. The analysis of array comparative genomic hybridization analysis revealed a 43.68-Mb duplication of 3p26.3-3p22.1 encompassing CHL1 and CNTN4, and an 8.66-Mb deletion of 7q36.1-7q36.3 encompassing SHH in the fetus.

CONCLUSION

Simultaneous occurrence of 7q deletion and 3p duplication can be associated with alobar holoprosencephaly. For the couple with a parental translocation involving 7q and 3p, prenatal ultrasound should include a detailed investigation of central nervous system anomalies.

Deletion of 7q33-q35 in a Patient with Intellectual Disability and Dysmorphic Features: Further Characterization of 7q Interstitial Deletion Syndrome

This case report concerns a 16-year-old girl with a 9.92 Mb, heterozygous interstitial chromosome deletion at 7q33-q35, identified using array comparative genomic hybridization. The patient has dysmorphic facial features, intellectual disability, recurrent infections, self-injurious behavior, obesity, and recent onset of hemihypertrophy. This patient has overlapping features with previously reported individuals who have similar deletions spanning the 7q32-q36 region. It has been difficult to describe an interstitial 7q deletion syndrome due to variations in the sizes and regions in the few patients reported in the literature. This case contributes to the further characterization of an interstitial distal 7q deletion syndrome.

Chromosomal deletions detected at amniocentesis

OBJECTIVE

The aim of this study is to present the incidence, prenatal and postnatal findings, and modes of ascertainment in chromosomal deletions detected at amniocentesis.

MATERIALS AND METHODS

We reviewed all the cases with chromosomal deletions, which were detected by amniocentesis in Mackay Memorial Hospital, Taipei, Taiwan, between January 1987 and December 2012. Data on the locations and types of deletion, reasons for performing amniocentesis, maternal age, gestational age at amniocentesis, fetal karyotypes, inheritance of deletions, and relative prenatal findings were collected.

RESULTS

Amniocentesis was performed in 33,305 cases within this period of time. Among these, 31 cases of chromosomal deletions were considered for the study. The mean gestational age at amniocentesis was 21.0 weeks (range from 15 weeks to 32 weeks) and the mean maternal age at amniocentesis was 32.1 years (range from 26 years to 37 years). Nineteen cases (61.3%) manifested fetal structural abnormalities on ultrasound, nine (29.0%) presented no ultrasound abnormalities, and three had an unknown status. The main modes of ascertainment included abnormal ultrasound findings in 10 cases (32.2%), advanced maternal age in 11 cases (35.5%), abnormal maternal serum screening results in six cases (19.6%), and other reasons in four cases (13.0%). Of the 27 cases with known inheritance, the deletion was inherited in two (6.6%) and de novo in 25 (92.6%). Males accounted for 11 (35.5%) and females for 20 (64.5%) cases. Chromosomal deletions are more often to occur in chromosomal 5(4 cases, 12.9%), chromosomal 18 (4 cases, 12.9%), chromosomal 4 (3 cases, 9.7%), chromosomal 7 (3 cases, 9.7%), chromosomal 10 (3 cases, 9.7%), chromosomal 11 (3 cases, 9.7%), and chromosomal 1 (2 cases, 6.5%). There were four cases of chromosomal mosaicism: two involved chromosome 5, one involved chromosome 10, and one involved chromosome 18. Twenty-three cases (74.2%) had terminal deletions and the other eight cases (26.7%) had interstitial-type deletions.

CONCLUSION

In summary, we have presented the results of prenatal diagnosis for chromosomal deletions using amniocentesis. Chromosomal deletions are more likely to occur in females and more often in chromosomal 5p and 18q. Prenatal diagnosis at amniocentesis is frequently associated with advanced maternal age, abnormal ultrasound findings, and abnormal maternal serum screening. The frequency of ascertainment in chromosome deletion seems to be directly correlated with advanced maternal age and abnormal ultrasound findings. In cases with terminal deletions, prenatal ultrasound plays a more important role for prenatal diagnosis.

Esophageal stenosis in a child presenting a de novo 7q terminal deletion

We report on the first case of a child with a de novo 7q terminal deletion [46,XX,del(7)(q35 → qter)] presenting esophageal stenosis. This cytogenetic abnormality was confirmed by FISH, using subtelomeric probes, and by a whole-genome array-CGH assay. The child also had phenotypic features previously described in patients with a similar deletion, as growth retardation, microcephaly, coloboma of papilla, ptosis, hearing loss, urinary tract anomalies, partial agenesis of sacrum, hypotonia and neuropsychomotor delay. The odontoid hypoplasia identified, in similarity with the esophageal stenosis, represents an uncommon finding. This report is also the first clinical description of a patient with an abnormality involving the sonic hedgehog gene and an esophageal alteration. It is discussed the possibility of a specific association between them, according to some results observed in studies with animal models.

De novo Subtelomeric Deletion Additional to an Inherited Apparently Balanced Reciprocal Translocation

OBJECTIVE

We describe the analysis of an apparently balanced inherited reciprocal translocation in a fetus presenting with multiple congenital abnormalities, characterize the structural chromosome rearrangement, and report an unexpected additional imbalance to the inherited rearrangement.

METHODS

DNA microarray was used to screen for genomic imbalance in subtelomeric and interstitial critical regions. High-resolution comparative genomic hybridization was used to screen for genomic imbalance at a genome-wide level. Fluorescence in situ hybridization using whole-chromosome painting and specific probes was used to characterize the inherited translocation, and the size of the de novoadditional deletion.

RESULTS

An unexpected additional deletion was found in 7qter on derivative 10 of the inherited maternal reciprocal translocation t(7;10)(q11.23; p14).

CONCLUSIONS

We show the usefulness of genome-wide and specific molecular cytogenetic techniques to explore apparently balanced rearrangements.

Prenatal Diagnosis of a Partial Monosomy 7q11→q31 in a Fetus with Split Foot

OBJECTIVE

A 27-year-old woman was referred to our laboratory for genetic counseling at 26 weeks of gestation due to abnormal ultrasound findings including intrauterine growth retardation, Dandy-Walker malformation and lower extremity anomalies.

METHODS

Chromosome analysis was performed on fetal blood sample obtained by cardiocentesis.

RESULT

We observed an abnormal karyotype with a structural abnormality of the long arm of chromosome 7. Both parents' chromosomes were normal; thus, the fetal karyotype designation was 46,XX, del(7)(pter-->q11::q31-->qter) de novo. Skin biopsy sample was taken to confirm the karyotype after therapeutic abortion was performed. The result was identical. Postmortem examination and autopsy showed facial dysmorphism, malformations of the lower extremities and central nervous system anomalies.

CONCLUSION

7q interstitial deletions cause a wide spectrum of congenital abnormalities and syndromes linked to the deleted segments. Our case had a rather wide chromosome region deleted and it is important, because prenatal diagnosis was performed. Thus, the family had the chance to evaluate the situation and decided to terminate the pregnancy after genetic counseling.