Biomaterial Database

Fitting mixture distributions to phenylthiocarbamide (PTC) sensitivity. 1991

P N Jones, and G J McLachlan

C.S.I.R.O. Biometrics Unit, Brisbane, Australia.

A technique for fitting mixture distributions to phenylthiocarbamide (PTC) sensitivity is described. Under the assumptions of Hardy-Weinberg equilibrium, a mixture of three normal components is postulated for the observed distribution, with the mixing parameters corresponding to the proportions of the three genotypes associated with two alleles A and a acting at a single locus. The corresponding genotypes AA, Aa, and aa are then considered to have separate means and variances. This paper is concerned with estimating the parameters of the model, and their standard errors, by using an application of the EM algorithm. This technique also caters for the fact that the sensitivity measurements are only known to lie between the endpoints of certain intervals and that the exact measurement of the attribute is not possible.

UI	MeSH Term	Description	Entries
D008957	Models, Genetic	Theoretical representations that simulate the behavior or activity of genetic processes or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.	Genetic Models,Genetic Model,Model, Genetic
D010670	Phenylthiourea	Phenylthiourea is a THIOUREA derivative containing a phenyl ring. Depending on their genetic makeup, humans can find it either bitter-tasting or tasteless.	Phenylthiocarbamide
D005838	Genotype	The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.	Genogroup,Genogroups,Genotypes
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000465	Algorithms	A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.	Algorithm
D000483	Alleles	Variant forms of the same gene, occupying the same locus on homologous CHROMOSOMES, and governing the variants in production of the same gene product.	Allelomorphs,Allele,Allelomorph
D013652	Taste Threshold	The minimum concentration at which taste sensitivity to a particular substance or food can be perceived.	Taste Thresholds,Threshold, Taste,Thresholds, Taste
D016010	Binomial Distribution	The probability distribution associated with two mutually exclusive outcomes; used to model cumulative incidence rates and prevalence rates. The Bernoulli distribution is a special case of binomial distribution.	Bernoulli Distribution,Negative Binomial Distribution,Binomial Distribution, Negative,Binomial Distributions,Binomial Distributions, Negative,Distribution, Bernoulli,Distribution, Binomial,Distribution, Negative Binomial,Distributions, Binomial,Distributions, Negative Binomial,Negative Binomial Distributions