Question

What is Multifactorial disorder?

Answer 1

A polygenic mode of inheritance is caused or marked by a number of genes at various loci. The principle of multifactorial (polygenic) inheritance is that numerous distinct gene loci can affect a single component of the phenotype (a single character); multifactorial diseases are caused by the simultaneous action of multiple genetic or environmental factors.

Complete answer:
Multifactorial diseases aren't limited to any one pattern of single-gene inheritance; they're more likely to be linked to many genes as well as environmental factors. In reality, the terms "multifactorial" and "polygenic" are sometimes used interchangeably to describe the architecture of disease-causing genetic components. Despite the fact that multiple diseases are frequently observed in families, there is no clear pattern of inheritance. Because specific factors related with these diseases have yet to be established, it is challenging to investigate and treat multifactorial diseases.
The Multifactorial threshold model assumes that multifactorial trait gene abnormalities are frequently dispersed throughout populations. To begin with, various populations may have varying thresholds. When the incidence of an illness differs between males and females, this is referred to as a male-female difference (e.g. Pyloric stenosis). The susceptibility distribution is the same, but the threshold is different. Second, while the threshold may be the same, susceptibility distributions may differ. It describes the underlying hazards that affected persons' first-degree relatives face.
Multifactorial diseases are caused by the simultaneous action of multiple genetic and/or environmental factors. Seven frequent multifactorial genetic inheritance problems are heart disease, high blood pressure, Alzheimer's disease, arthritis, diabetes, cancer, and obesity.

Note:-
Multiple genetic and environmental factors combine to cause multifactorial diseases. Determining disease heritability, segregation analysis to determine the genetic model, linkage or association mapping to identify genetic loci underlying the disease, fine mapping to determine causal variants, and replication and functional analysis to confirm the initial findings are all steps in the study of multifactorial disease.