A Sickeningly Sweet Baby Boy
A Case Study of Recessive Inheritance in Inbred Populations
Department of Biology and Chemistry
Department of Biology
When a newborn develops symptoms eerily similar to those of an older sibling who died shortly after birth, his Mennonite parents are understandably alarmed. They soon discover that their son has Maple Syrup Urine Disease (MSUD), a recessively inherited metabolic disorder. This case explores the genetics of the disease and the ultimate dilemma of treatment options. Developed for an introductory non-majors biology course, the case can also be used in other science or health related courses such as human genetics and biochemistry.
- Explain the relationships between family members and the disease incidence using a pedigree chart.
- Understand the rules governing the inheritance of a single gene recessive disorder.
- Calculate the probabilities of inheriting recessive traits and passing them on to offspring.
- Explain the dietary restrictions associated with MSUD.
- Discuss the risks associated with liver transplants.
- Discuss the options of genetic screening and genetic testing in this case.
- Compare the advantages and disadvantages associated with gene therapy and more conventional treatment means, i.e., transplants.
- Explore genetic drift effects on small populations (e.g., the Mennonite community), including other possible conditions resulting from a founder effect in similar communities.
KeywordsMetabolic disorder; recessive disorder; genetic disease; genotype; phenotype; homozygous; heterozygous; Maple Syrup Urine Disease; MSUD; pedigree chart; founder effect; liver transplantation; Mennonites; Pennsylvania
Educational LevelHigh school, Undergraduate lower division, Undergraduate upper division
Type MethodsInterrupted, Dilemma/Decision
Subject HeadingsBiology (General) Genetics / Heredity Biochemistry Medicine (General)
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