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Homozygosity for autosomal dominant Marfan syndrome
Abstract:
Marfan syndrome is an autosomal dominant condition with varying phenotypic manifestations. Affected persons are usually heterozygotes. A family is presented in which the gene for this syndrome is segregating in a large number of members. Two sibs suffered from unusually severe, identical, and fatal manifestations from birth, their parents having mild cardiovascular and somatic symptoms common in Marfan syndrome. Investigation of collagen biosynthesis in fibroblasts revealed no abnormalities in fibronectin and procollagen I and III synthesis and secretion or in the procollagen to collagen conversion. We suggest that these two sibs are examples of homozygosity for the Marfan syndrome gene, based on the large number of affected members, the absence of additional consanguinity, manifestation of the syndrome in both parents, and the severity of the disease in the two sibs.
Insights
Marfan syndrome, typically seen in heterozygotes, presented with severe, fatal symptoms in two siblings. This suggests possible homozygosity for the Marfan syndrome gene, a rare occurrence.
Area of Science:
- Genetics
- Molecular Biology
- Medical Genetics
Background:
- Marfan syndrome is an autosomal dominant genetic disorder.
- It typically affects individuals in a heterozygous state.
- Phenotypic manifestations can vary widely among affected individuals.
Observation:
- A family with a large number of Marfan syndrome cases was studied.
- Two siblings exhibited unusually severe, identical, and fatal symptoms from birth.
- Their parents displayed milder, characteristic Marfan syndrome symptoms.
Findings:
- Collagen biosynthesis in fibroblasts showed no abnormalities in fibronectin or procollagen I and III synthesis, secretion, or conversion.
- The severe presentation in siblings, with affected parents and no consanguinity, supports homozygosity.
Implications:
- This case suggests the possibility of homozygous Marfan syndrome, a rare condition.
- Understanding homozygous Marfan syndrome is crucial for accurate diagnosis and genetic counseling.
- Further research into the genetic basis of severe Marfan syndrome phenotypes is warranted.