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Genetic diagnosis of Werdnig-Hoffmann disease: a problem for application to prenatal diagnosis
Makoto Migita1, Makoto Migita, Yohko Uchikoba
1Department of Pediatrics, Nippon Medical School, Tokyo, Japan. Makoto-Migita-bmb@nms.ac.jp
Insights
A floppy infant diagnosed with spinal muscular atrophy (SMA type 1) and Klinefelter syndrome highlights genetic complexities. Genetic testing confirmed SMA type 1, prompting caution for future prenatal diagnoses due to potential sample contamination.
Area of Science:
- Genetics
- Neurology
- Pediatrics
Background:
- Spinal muscular atrophy (SMA) type 1, also known as Werdnig-Hoffmann disease, is a severe genetic neuromuscular disorder.
- Klinefelter syndrome is a genetic condition that affects males.
Purpose of the Study:
- To report a rare case of a floppy infant with concurrent SMA type 1 and Klinefelter syndrome.
- To detail the genetic diagnostic process for SMA type 1 in an infant.
- To discuss implications for prenatal diagnosis in subsequent pregnancies.
Main Methods:
- Genetic counseling was provided to the parents.
- DNA analysis was performed on the infant's peripheral blood mononuclear cells.
- Polymerase chain reaction (PCR) was used to detect gene deletions associated with SMA type 1.
Main Results:
- The infant was confirmed to have SMA type 1 due to deletions in the survival motor neuron (SMN) gene (exons 7 and 8) and the neuronal apoptosis inhibitory protein (NAIP) gene (exons 4 and 5).
- The genetic findings confirmed the diagnosis of SMA type 1.
Conclusions:
- This case underscores the importance of comprehensive genetic evaluation in infants presenting with complex phenotypes.
- The limitations of PCR-based genetic testing, particularly regarding potential maternal tissue contamination in chorionic villi samples, necessitate careful application in prenatal diagnosis for SMA type 1.
Abstract:
We report a floppy infant with Werdnig-Hoffmann disease (spinal muscular atrophy: SMA type 1) and Klinefelter syndrome. After genetic counseling with parents, a genetic diagnosis using DNA from the infant's peripheral blood mononuclear cells was performed. The parents' deletion of exons 7 and 8 of the survival motor neuron (smn) gene and exons 4 and 5 of the neuronal apoptosis inhibitory protein (naip) gene were noted in the infant, so he was confirmed to have SMA type 1. The parents wanted to receive a prenatal diagnosis on the next pregnancy. However this genetic test is achieved by confirming that a specific band can not be detected by PCR. Therefore, this method should be applied with great care to prenatal diagnosis using chorionic villi, which may be contaminated with maternal tissue.