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Uniparental disomy 7 in Silver-Russell syndrome and primordial growth retardation
D Kotzot1, S Schmitt, F Bernasconi
1Institute of Medical Genetics, University of Zürich, Switzerland.
Insights
Maternal uniparental disomy of chromosome 7 (UPD 7) is linked to growth retardation. This study found UPD 7 in four patients with Silver-Russell syndrome or primordial growth retardation, confirming a maternally imprinted gene on chromosome 7.
Area of Science:
- Genetics
- Reproductive Biology
- Pediatrics
Background:
- Maternal uniparental disomy (UPD) for chromosome 7 is rare, associated with intrauterine and postnatal growth retardation.
- Previous cases were identified through genetic screening for cystic fibrosis and COL1A2 mutations.
Purpose of the Study:
- To investigate the prevalence of maternal UPD 7 in patients with Silver-Russell syndrome (SRS) or primordial growth retardation (PGR).
- To identify potential imprinted genes on chromosome 7 responsible for these growth disorders.
Main Methods:
- Utilized PCR markers to analyze DNA from 35 patients with SRS or PGR and their parents.
- Screened for uniparental disomy of chromosome 7 (UPD 7).
Main Results:
- Maternal UPD 7 was detected in four out of 35 patients (11.4%).
- Three patients exhibited isodisomy, and one showed heterodisomy for chromosome 7.
- These findings support the presence of a maternally imprinted gene on chromosome 7.
Conclusions:
- Maternal UPD 7 is a significant factor in sporadic cases of SRS and PGR.
- Recommend screening for UPD 7 in patients presenting with these growth abnormalities.
- Suggests the existence of one or more maternally imprinted genes on chromosome 7 influencing growth.
Abstract:
Maternal uniparental disomy for the entire chromosome 7 has so far been reported in three patients with intrauterine and postnatal growth retardation. Two were detected because they were homozygous for a cystic fibrosis mutation for which only the mother was heterozygous, and one because he was homozygous for a rare COL1A2 mutation. We investigated 35 patients with either the Silver-Russell syndrome or primordial growth retardation and their parents with PCR markers to search for uniparental disomy 7. Four of 35 patients were found to have maternal disomy, including three with isodisomy and one with heterodisomy. The data confirm the hypothetical localization of a maternally imprinted gene (or more than one such gene) on chromosome 7. It is suggested to search for UPD 7 in families with an offspring with sporadic Silver-Russell syndrome or primordial growth retardation.