Recently, the "soul bargaining" of the National Medical Insurance Bureau on "Northinal sodium injection" has brushed the screen again, behind the "gentle and firm", is the country's attention to the small group of rare diseases!
In fact, spinal muscular atrophy (SMA) is not a rare disease, and "sky-high drugs" are not far away from us. Today, let's rub the hot spot to talk about this number one killer hidden around us again!
Let's start with an account:
Northinalsan sodium injection, after the price adjustment is 33,000 yuan / bottle, SMA children need to inject 6 injections in the first year, and then inject 3 injections per year thereafter, which costs about 100,000 yuan per year.
SMA pathogenic genes [carrier screening], the cost ranges from 500 to 3000 yuan (the price of SMA single examination and screening for a variety of high-risk genetic diseases is different).
Readers must be confused, is there a comparison between the two?
Yes, this is the prevention of "not getting sick". Through pre-pregnancy carrier screening, scientific pregnancy preparation can block the occurrence of diseases, and from then on, with spinal muscular atrophy (SMA) and "sky-high drugs" say Bye-bye!
1
What is spinal muscular atrophy?
Spinal muscular atrophy (SMA) is an autosomal recessive neurodegenerative disease, the most common cause is the survival motor neuron 1 (SMN1) gene homozygous deletion/mutation, resulting in spinal cord anterior horn and bulbar motor neuron degeneration, the patient can develop proximal limb and trunk progressive, symmetrical muscle weakness and muscle atrophy, severe SMA children if not effective treatment, 80% die of respiratory failure within one year of age.
As a result, SMA is the number one killer of fatal genetic diseases in children under 2 years of age.
2
"Rare diseases" are not uncommon
The incidence of SMA in live birth fetuses is about 1/6,000 to 1/10,000, and its incidence seems to be low, but it is not known that the carrying rate of SMA pathogenic genes in the population is as high as 1/40 to 1/50.
From the population base estimates, there are about 30 million SMA pathogenic gene carriers in China, once the two carriers marry and have children, each fetus has a 1/4 probability of giving birth to SMA children.
The genetic pattern of the disease can be understood like this:
The SMN1 gene that controls motor neurons has a pair, called brothers, from father and mother.
As long as one of the two brothers is healthy, the motor neurons can work normally, and if the two brothers are sick at the same time, the motor neurons will not work, and they will show muscle weakness or muscle atrophy.
If both parents carry a problematic gene, there is a 1 in 4 chance of having a sick child
Friends who feel that reading text is time-consuming look here
3
Early detection, early diagnosis, and early treatment are key
Although the National Health Insurance Bureau has cut drug prices to the minimum, "prevention before they happen" is still the most important way to block. Screening of people with population carriers, scientific preparation for pregnancy, early diagnosis and early treatment of symptomatic people are the key.
Primary prevention: screening of carriers of SMA pathogenic genes before and during pregnancy (using a means to screen couples carrying recessive disease-causing mutation genes and scientifically prepare for pregnancy so that they can produce healthy offspring);
Secondary prevention: chorionic hair, amniotic fluid, cord blood for prenatal diagnosis, and then genetic counseling;
Tertiary prevention: after birth, the treatment plan is determined according to the screening and diagnostic results, and the intervention and treatment are carried out as soon as possible.
4
The first line of defense: screening of carriers before pregnancy
Pre-pregnancy carrier screening, for this specific genetic disease, a couple only needs to be screened once in a lifetime. At present, European and American countries have incorporated SMA carrier screening into routine examinations.
In 2006
Taiwan began to promote SMA general screening, and now it has basically entered the stage of national general screening;
In 2008
ACMG (American Society of Medical Genetics and Genomics) recommends pan-ethnic screening for SMAs, i.e., indiscriminate SMA screening for all populations of childbearing age, regardless of region, race;
In 2017
The ACOG (American Association of Obstetricians and Gynecologists) recommends SMA screening for all people who are planning to be pregnant or are already pregnant;
In 2018
The FAC (U.S. Federal Advisory Committee) recommends SMA screening for all newborns.
5
How is carrier screening done?
Carrier screening only needs to be done with blood draws. Before pregnancy, the copy number of the pregnant woman's peripheral blood can be quantitatively analyzed, and if the test results are abnormal, the husband will draw blood to see if he carries the same "bad gene".
Of course, if the economy allows, both husband and wife can also check at the same time, which can save the time that the husband waits for the test after the woman's results are abnormal.
6
Both husband and wife are carriers, how to break?
If both husband and wife are carriers of SMA pathogenic genes, and each pregnancy has a 1/4 probability of having a child with SMA, how to avoid this 25% chance?
Fertility can be assisted by third-generation IVF, i.e. preimplantation genetic testing (PGT). The technique is to detect pathogenic variations in embryos that are developed in vitro fertilized to the blastocyst stage, and select healthy embryos that do not carry pathogenic variants for transfer, thereby preventing the occurrence of disease in offspring.
At present, Zhuozheng Medical has carried out 18 kinds of high-risk genetic disease carrier screening, and expectant mothers who are pregnant or are pregnant can come to consult and test.
Resources:
1. Spinal muscular atrophy. Up to date.
2.Kolb SJ, Kissel JT. Spinal muscular atrophy: a timely review. Arch Neurol. 2011;68(8):979-984.
3. Writing Group of Clinical Practice Guidelines for Genetic Diseases of Medical Genetics Branch of Chinese Medical Association, Pan Jianyan, Tan Hu, et al. Clinical practice guidelines for spinal muscular atrophy[J].Chinese Journal of Medical Genetics,2020,37 (03): 263-268.
4.American College of Obstetricians and Gynecologists (ACOG): Committee opinion on carrier screening for genetic conditions (2017).
Reviewer of this article
Dr. Cho Jeong Medical Dr. Mu Tian