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1. Biochemical Testing

Principle

It detects the presence of specific proteins or substances in blood, urine, amniotic fluid, or amniotic membrane cells usin chemical methods.

Purpose

Used to diagnose genetic defects caused by imbalances in certain proteins. It is commonly used to test protein levels for conditions like phenylketonuria (PKU).

Sample Types

Blood, urine, amniotic fluid, amniotic membrane cells.

2. Chromosomal Analysis

Principle

Directly examines the number and structure of chromosomes for abnormalities, rather than mutations in specific genes.

Purpose

Typically used to diagnose fetal chromosomal abnormalities, such as Down syndrome (trisomy 21). Common chromosomal abnormalities include numerical (e.g., trisomy syndromes) and structural abnormalities (e.g., translocations, deletions).

Sample Types

Blood samples and cells were obtained via amniocentesis or chorionic villus sampling (CVS).

Process

Cells are stained to highlight chromosome structures and then examined under a microscope for abnormalities.

3. DNA Analysis

Principle

Identifies and analyzes the sequence of specific genes to detect gene mutations or abnormalities.

Purpose

Used to diagnose genetic diseases caused by mutations in single genes, such as Huntington's disease, cystic fibrosis, etc.

Sample Types

Blood or fetal cells.

Process

After DNA extraction, techniques like PCR amplification, gene sequencing, etc., are used to analyze the sequence of specific genes.

Each type of genetic testing method has specific applications and advantages. Biochemical testing is suitable for metabolic diseases caused by protein dysfunction, chromosomal analysis detects larger-scale chromosomal abnormalities, and DNA analysis examines gene mutations and sequence abnormalities at a molecular level. Choosing the appropriate genetic testing method depends on the specific diagnostic needs to accurately diagnose and prevent genetic diseases.