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Flashcards in CBCL 1 Deck (27)
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What are the characteristics of an autosomal recessive trait?

Both parents of affected child are unaffected carriers Males and females are equally affected


How does whole genome sequencing compare to whole exome sequencing?

Whole genome is the entire shabang and the whole exome is only protein coding regions.


What is a null allele?

If no product or function results from an allele


What is a De Novo mutation?

When a mutation occurs randomly and has a dominant effect. It makes it difficult because you cannot use inheritance patterns


What is penetrance?

the likelihood that a characteristic manifests itself


What are the characteristics of X-linked dominant inheritance?

Both males and females can be affected, but less evident in females Females are less affected because of random X inactivation and mosaicism May appear autosomal dominant but no male to male transmission


What type of pedigree is this?

X-linked recessive


What is a haplotype?

a set of polymorphisms in different genes that reside closely on a given chromosome and are often inherited together. 


What is non-penetrance?

failure for a characteristic to manifest itself


What is a dominant negative?

when the normal function of the product is lost due to interference from the abnormal product


What are the characteristics of an autosomal dominance inheritance?

Males and females are equally effected Both can transmit the traits Affected person has at least one affected parent There is a 50% probability of transmitting the trait to any offspring


What type of pedigree is this?

Autosomal dominant


What is variable expressivity?

Different features of a disorder may be evident in different members of the same family.


How does somatic mosaicism compare to germline mosaicism?

Somatic only involves the cells of the individual and germline is what is passed down to the next generation


What is a modifier gene?

can either increase or decrease the penetrance of a disorder


What is a compound heterozygote?

The presence of two different mutant alleles at a particular gene locus, one on each chromosome of a pair. The human genome contains two copies of each gene, a paternal and a maternal allele.


What type of pedigree is this?

Autosomal recessive


What is a loss of function mutation?

LOF produces a reduced amount or a reduced activity of the product. This has minimal effect unless it is on both alleles (recessive).


What type of pedigree is this?

Autosomal Dominant


What is haploinsufficiency?

when a 50% product level results in altered phenotype


What is anticipation?

The phenotype worsens with successive generations


What are the characteristics of fragile X syndrome?

In normal patients within the FMR1 gene the CGG segment is repeated 5-40 times. In fragile X pts this same CGG segment is repeated more than 200 times, which silences the FMR1 gene. Since boys only have one X chromosome it can effect boys more than girls but not always.


What are the characteristics of X-linked recessive inheritance?

Males mostly affected All daughters of affected males are carriers No male to male transmission


What is gain of function?

increased amount or increased activity of the product usually dominant


What is genetic locus?

specific location or position of a gene's DNA sequence, on a chromosome.


What type of pedigree is this?

X-linked dominant


What is a polymorphism?

A specific change that occurs commonly in a population and is not associated with a disease phenotype