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Prenatal diagnosis of trisomy 12 mosaicism: physical and developmental follow-up
J M Meck1, C Kozma, J G Tchabo
1Department of Obstetrics and Gynecology, Georgetown University Medical Center, Washington, DC 20007.
Insights
This study followed a child diagnosed prenatally with mosaic trisomy 12. Follow-up evaluations revealed normal physical and developmental outcomes, suggesting potential resolution of the chromosomal abnormality.
Area of Science:
- Genetics
- Developmental Biology
- Prenatal Diagnosis
Background:
- Prenatal diagnosis of chromosomal abnormalities like trisomy 12 requires careful follow-up.
- Mosaicism, where some cells have an extra chromosome and others do not, presents diagnostic challenges.
- Trisomy 12 is a rare chromosomal condition with variable clinical outcomes.
Observation:
- A child was diagnosed with mosaic trisomy 12 (22% of cells) via prenatal amniocentesis.
- Postnatal chromosomal analyses of cord blood, placenta, and skin fibroblasts did not detect the trisomy 12 cell line.
- The child exhibited normal physical and neurological development at 2 years 8 months and 5 years of age.
Findings:
- Postnatal chromosomal studies did not confirm the prenatal diagnosis of trisomy 12.
- The child demonstrated age-appropriate psychomotor development.
- No clinical manifestations of trisomy 12 were observed during follow-up evaluations.
Implications:
- This case highlights the potential for chromosomal abnormalities detected prenatally to resolve or be confined to the placenta.
- It underscores the importance of comprehensive postnatal evaluation for children with prenatal findings of mosaicism.
- Further research is needed to understand the long-term implications and mechanisms of chromosomal mosaicism resolution.
Abstract:
Follow-up evaluations were performed on a child at the ages of 2 years 8 months and also at 5 years who had been found on prenatal amniocentesis to be mosaic for trisomy 12. Eight of 36 colonies (22 per cent) were trisomy 12 at amniocentesis, with the remaining colonies showing a normal female karyotype. Cord blood, amnion, chorion, placental, and skin fibroblast chromosome studies failed to show any further evidence of a trisomy 12 cell line. At her evaluations, the child had normal physical and neurological findings. Psychomotor development was appropriate for age on screening.