Genetic medicine services are designed to reduce the pain of genetic patients and to provide clinical services to those with genetic disorders, including the diagnosis, therapy and prevention of genetic diseases. With the enhancement of people's health consciousness, the genetic medical service is getting more and more attention.

Genetic disease diagnosis refers to the doctor to make a definite diagnosis whether a disease is a genetic disease, including prenatal diagnosis, pre-symptom diagnosis and symptomatic diagnosis. In order to confirm whether it is a genetic disease or not, in addition to the diagnostic method of general disease, special genetics diagnostic means should be supplemented.

Symptomatic diagnosis refers to the analysis of the clinical manifestations of the patients who have presented symptoms, making a definite diagnosis of genetic disorders and judging the genetic model.

In addition to the general history of the disease, it is important to focus on the collection of projects related to the cluster of hereditary diseases, including family history, marriage history and reproductive history.

Most genetic diseases have corresponding signs and symptoms in infants or childhood. In addition to specific symptoms and physical signs, it is also important to observe whether the development, intelligence, sexual organs and secondary sexual characteristics are abnormal or not. These will provide clues to the preliminary judgment of the disease.

Based on the survey results of patients and family members to draw the pedigree diagram, which helps to confirm whether genetic disorders are monogenic diseases or polygenic diseases, and determine inheritance modes or newly- genetic mutation.

1. Chromosomal examination or karyotype analysis

Chromosomal examination is the main method for the diagnosis of chromosomal disease, which can accurately detect various chromosomal abnormalities and various abnormal karyotypes.

Specimens for chromosome examination: umbilical cord blood, chorionic cells, amniotic fluid cells, peripheral blood, bone marrow and various tissues, etc.

Indications of chromosome examination:

A. Growth retardation, mental retardation and accompanied with other congenital malformations.

B. Couples have experienced the history of spontaneous miscarriage or multiple miscarriages, stillbirth, neonatal death and fetal monster.

C. Both wife and husband suffer from congenital infertility and sterility.

D. There are patients with hermaphroditism or sexual characteristics hypoplasia.

E. There are chromosomal abnormalities or congenital anomalies in the family.

F. Pregnant women over 35 years old.

G. Tall and irascible males.

H. Persons who have received radiation or ionizing radiation for a long time.

2. Sexual chromatin examination

The examination of sex chromatin includes X chromatin examination and Y chromatin examination. It is of certain significance for the diagnosis of fetal sex, hermaphroditic deformity and abnormal sex chromosome number, but the diagnosis still needs a chromosome examination.

Specimens for sexual chromatin examination: oral mucosa, vaginal mucosa, amniotic fluid cells and chorionic cells, etc.

Biochemical examination is mainly to analyze the changes of proteins, enzymes and their intermediate metabolites,etc. caused by genetic mutations. This method is suitable for the examination of genetic diseases, such as molecular diseases, congenital metabolic defects, and immune deficiency. For example, phenylketonuria (PKU) can be definitely diagnosed through detecting phenylphruvic acid or phenyl acetic acid in urine.

Gene diagnosis refers to the use of molecular biological technologies, such as nucleic acid hybridization, polymerase chain reaction (PCR), DNA sequencing technology, Restriction fragment length polymorphism analysis (RFLP), to detect the structure and expression of the gene directly from the gene level (DNA or RNA), so as to make a diagnosis of the disease. Gene diagnosis has the characteristics of strong pertinence, high specificity, high sensitivity and wide adaptability. Genetic diagnosis has the advantage of taking material without the restriction of the cell type.

Various measures are taken on genetically abnormal individuals, so that they are genetically confirmed prior to the onset of symptoms. This can help both effective treatment in advance and genetic counseling.

Prenatal diagnosis refers to the analysis and diagnosis of the chromosomes and genes of the fetus, which is an effective means to prevent the birth of children with hereditary diseases. It analyzes the genetic and biochemical tests of amniotic fluid, amniotic fluid cells and villiis basing on the techniques of amniocentesis and villus sampling.

Therapy of genetic disorders includes traditional treatment and gene therapy.

Traditional treatments of genetic diseases usually take symptomatic treatment strategies to correct deformities, improve symptoms, regulate function and improve the quality of life of patients. Traditional treatment includes surgical treatment, dietary treatment, medication control and physiotherapy.

Surgery can not only correct deformities (such as cleft palate), repair and removal of damaged organs, but also perform tissue or organ transplantation (such as liver transplantation) for the treatment of genetic diseases.

Medication treatment and dietary treatment are mainly used to treat metabolic disturbance of genetic disorders, and its principles are restriction, removal and supplementation.

I. Restriction

For patients who are accumulation of substrate or intermediate products caused by enzyme deficiency, a special diet is developed to control the condition by limiting the intake of the substrate, so as to achieve the goal of treating diseases.

Galactohyperemia patients. Limit the intake of lactose and galactose during pregnancy. Dairy products are strictly prohibited after birth.

Phenylketonuria patients. Advocate early diagnosis and early treatment. Low phenylpyruvic acid diet for children. Glucose-6-phosphate dehydrogenase deficiency patients. Forbidden to eat fava beans and contact fava bean pollen. Drugs such as primaquine and aspirin are strictly prohibited.

II. Removal

For some of the enzymatic reaction barriers, leading to a storage excessive accumulation of metabolites in the body, can use various physical and chemical methods, such as chelating agent, inhibitor, eccritic, exchange transfusion or plasmapheresis, etc., to excrete out or restrain the generation of toxicant. For example, patients with familial hypercholesterolemia are treated with cholestyramine to reduce their blood cholesterol levels.

III. Supplementation

Most molecular diseases and hereditary metabolic diseases are caused by protein or enzyme deficiency. Therefore, supplementation can improve the symptoms and achieve the purpose of treatment. Some of the female diseases caused by X chromosome aberration can supplement the estrogen and make the second characteristics of the patient develop. Pituitary dwarfism can be treated with growth hormone. Diabetics can inject insulin to improve their symptoms.

Gene therapy refers to the use of recombinant DNA technology to replace or repair the pathogenic genes in defective cells of patients, to correct or compensate for the diseases caused by genetic defects and abnormalities, so as to achieve the purpose of treatment. Gene therapy opens up a path to cure genetic disorders.

Somatic gene therapy refers to introducing exogenous gene into patients’ somatic cells. Germ cell therapy refers to introducing exogenous gene into patients’ germ cells. At present, somatic gene therapy is the common treatment approach.

Target cells refer to cells that receive exogenous genes and can be used for treatment. Target cells should have the characteristics of potential proliferation capacity, long longevity, being easy to produce and multiply in vitro, accepting and expressing introduced gene. Commonly used target cells are bone marrow cells, liver cells, muscle cells, nerve cells and so on. Short-life cells are not suitable to act as target cells in gene therapy, such as epidermal cells.

I. Gene correction

A specific method, such as homologous recombination or targeted mutation, is used to repair the mutant DNA in situ, which can correct the mutation base sequence of the causative gene, and preserve the normal part. Although this approach is an ideal approach for gene therapy, but it is technically impossible.

II. Gene replacement

It refers to the removal of the whole mutant gene and replacement by a functional normal gene, so that the pathogenic gene is permanently corrected. Gene replacement therapy is actually the traditional so-called gene therapy.

III. Gene augmentation

The exogenous gene is introduced into the diseased cell, and its expression product can compensate the function of the defective cells or strengthen the original function.

IV. Gene interference

Introducing exogenous genes to interfere and inhibit harmful gene expression. For example, tumor suppressor genes (such as Rb or TP53) are imported into tumor cells to suppress abnormal expression of oncogenes.

V. Open the closed gene

For example, open the closed genes through demethylation.

I. Stability

Gene maybe do not express after introducing into target cells. If the life of target cell is short and gene will cannot last or high-efficient express.

II. Security

The use of viral vectors for gene therapy may cause infection or carcinogenic panic.

III. Ethicality

Gene discrimination versus gene improvement, and gene privacy versus informed right about gene are new thoughts about gene therapy.

The methods of combination with genetic counseling, prenatal diagnosis and genetic screening are used in the prevention of hereditary diseases, which greatly reduces the incidence of hereditary diseases and effectively improves the quality of population.

It refers to the use of routine medical care or experimental techniques for the general treatment or prevention of genetic diseases for early diagnosis and screening.

For example, prenatal screening of Down's syndrome through maternal serum screening (MSS); through DNA detection, and take the method of terminating pregnancy to prevent the birth of infants with congenital malformations (such as progeria).

Pre-symptom diagnosis of some genetic disease in newborn infants is an effective method to prevent and treat certain genetic diseases. For example, afrer the screening of neonatal phenylketonuria, dietary therapy should be taken as early as possible to prevent the intake of foods containing phenylalanine, which can effectively control the occurrence of diseases.

Carriers are individuals with normal phenotype but with pathogenic genes or abnormal chromosomes. For example, Guangxi province is a high incidence area of thalassemia, where the proportion of carriers with thalassemia gene is up to 205. Marriage guidance for thalassemia gene carriers is offered after screening of thalassemia heterozygotes.

Genetic counseling includes answering questions raised by patients or their relatives about pathogeny, hereditary mode, diagnosis, therapy and prevention of genetic disorders, and estimating recurrence risk and providing suggestions and guidance for patients and their relatives.

The types of genetic counseling include prenuptial counseling, prenatal counseling, and general consultation. The main steps of genetic counseling include accurate diagnosis, identification of genetic patterns, and estimation of recurrent risk, proposing strategies and measures, and follow-up and expansion of consultation.

Relieve the physical and mental pains of patients, relieve psychological pressure of patients and their relatives, help them correctly deal with genetic disorders and reduce the chance of transduction.

On the basis of genetic counseling, Genetic Consultation Center must be responsible for genetic registration, genetic follow-up and genetic health care.

There is a family of progeria in the city of HeZhou in Guangxi province, in which three children born by healthy parents are all suffering from progeria. Since 2015, clinical students from Guangxi Medical University have passed the summer social activities of “three times going to the countryside”, which not only have obtained rare genetic counseling opportunities, but also made “genetic counseling” into the medical and humane care content.