Screening for six rare and genetic diseases is systematically carried out in newborns in France. From January 1, 2023, this screening will include 7 new diseases including homocystinuria.
The national neonatal screening program concerns all newborns who are born in France. It aims to detect and treat early, if necessary, rare, severe and most often genetic diseases. It is carried out in the maternity ward (sometimes at home) in drawing drops of blood from a blotterfollowing one small sting in the heel (Guthrie test) or in the newborn’s hand. It is systematically proposed with the agreement of the parents.
What is newborn screening?
Established in the early 1970s, newborn screening test was initially limited to screening for phenylketonuria in 1972 then it was extended to thecongenital hypothyroidism in 1978, to the sickle cell disease in Overseas France in 1985 and 10 years later in a targeted manner in mainland France,‘congenital adrenal hyperplasia in 1995to the cystic fibrosis in 2002 and at the bilateral permanent deafness in 2012. “Guthrie’s test also makes it possible to detect whether the child is a “carrier” without being sick (healthy carrier), for example for the sickle cell disease et Cystic fibrosis“, specifies Dr. Monique Quillard, general practitioner and pediatrician. The diseases detected are rare and genetic diseasesthe list of which is fixed by ministerial decree. From January 1, 2023, 7 additional pathologies will complete this list.
What is the list of diseases screened at birth?
- phenylketonuria,
- congenital hypothyroidism,
- the cystic fibrosis,
- congenital adrenal hyperplasia
- deficiency in acyl-CoA dehydrogenase of medium-chain fatty acids or “Medium-Chain-Acyl-CoA Dehydrogenase“ (MCAD) since December 1, 2020.
- sickle cell disease “for newborns presenting a particular risk linked to their origins” says Dr Monique Quillard, general practitioner and pediatrician.
- l’homocystinurie (HCY) (from January 1, 2023)
- the leucinose (MSUD) (from January 1, 2023)
- the type 1 tyrosinemia (TYR-1) (from January 1, 2023)
- l’aciduria isovalerique (IVA) (from 1 January 2023)
- l’glutaric aciduria type 1 (GA-1) (from January 1, 2023)
- the long-chain fatty acid 3-hydroxyacyl-coenzyme A dehydrogenase deficiency (LCHAD) (from January 1, 2023)
- the carnitine uptake deficiency (CUD) (from January 1, 2023)
What are the new diseases detected from 2023?
In accordance with recommendations of the Haute Autorité de Santé in 2020seven additional diseases will be screened at birth from 1 January 2023:
- l’homocystinurie (HCY): abnormality of vitamin B12 characterized by a anemiabrain neurological damage and sometimes developmental delay.
- the leucinose (MSUD): disease characterized by difficulty eating, excessive sleep time, vomiting, neurological brain disorders and respiratory failure in the absence of treatment
- the type 1 tyrosinemia (TYR-1) which affects the kidneys and liver
- l’aciduria isovalerique (IVA): acute disorders at birth (vomiting, convulsions) or later disorders (growth and/or development delay);
- l’glutaric aciduria type 1 (GA-1) responsible for acute neurological disorders.
- the long-chain fatty acid 3-hydroxyacyl-coenzyme A dehydrogenase deficiency (LCHAD) responsible for hypoglycaemia which can cause liver damage and heart damage.
- the deficit in capture of carnitine responsible for cardiac involvement in early childhood, often associated with hypotonia, growth retardation, recurrent hypoglycaemic attacks and/or coma.
What is phenylketonuria?
The body of people with phenylketonuria cannot process phenylalanine, a protein found in the body and in food. It accumulates and, in excess in the body, it prevents the proper development of the child’s brain, causing cognitive disorders and psychomotor retardation.
What is congenital hypothyroidism?
This is a deficit in the production of the thyroid hormones T3 and T4, either because the newborn’s gland has not developed correctly, or because it is malfunctioning. “Without treatment, it can cause psychomotor developmental disorders and irreversible growth disorders“, says Dr. Quillard.
What is congenital adrenal hyperplasia?
It is a dysfunction of the adrenal glands. “It leads to poor production of certain hormones, mainly sexual, either in excess or in deficit. If left untreated, it causes growth and puberty disturbances.“, says our expert.
What is sickle cell disease?
It’s regarding a hereditary genetic disease affecting hemoglobin chains. The red blood cells are deformed, they take on a sickle shape. Because of this figure, they circulate badly, which can cause clots in the vessels, causing many complications such as anemia, bone infarctions, greater susceptibility to infections… There are no curative treatments : it consists of analgesics once morest pain, antibiotics in case of infections, blood transfusions sometimes and in case of very severe form, a bone marrow transplant. But trials are underway using gene therapy. “Nearly 120 million people in the world are carriers of a sickle cell mutation. In metropolitan France, the subjects affected would be 6,000 to 7,000, with 250 new cases diagnosed each year, especially in the Paris region.“, says Dr. Quillard.
What is cystic fibrosis?
This genetic disease responsible for breathing difficulties affects 1 in 4000 newborns in France, according to the Haute Autorité de Santé (2015). This genetic disease leads to an absence or dysfunction of the CFTR protein: this leads to the formation of mucus which freezes in the organs. Microbes are poorly evacuated, they stagnate, cause infections and inflammation responsible, little by little, for the destruction of the lungs and major digestive problems. The sick person breathes badly, has the feeling of suffocating while suffering from severe abdominal pain, digestion problems and episodes of diarrhoea. There is no curative treatment but preventive drugs, such as pancreatic enzymes, allow you to live almost normally. Regular treatment with respiratory physiotherapy also improves the patient. However, life expectancy does not exceed 34 ans.
What is MCAD Deficiency?
MCAD deficiency is a condition screened at birth for children born on or following December 1, 2020. MCAD deficiency is an inherited condition characterized by the body’s inability to use certain fats (fatty acids) as a source of energy. Thanks to birth screening, a suitable diet helps to avoid the complications of this disease and will allow the child to develop normally.
What are the newborn screening exams?
Of the the third day of life infant, a small blood sample is performed in the heel or in a vein (Guthrie test). “It is carried out by taking drops of blood on a blotter, following a small puncture in the heel of the newborn, explains the pediatrician. It is systematically offered but parental consent is required. Realized freesampling is most often done in the maternity ward, sometimes at home, at the earliest 48 hours following birth, at best 72 hours. It is produced by a specialized laboratory”. Since January 1, 2022, maternity units and professionals carrying out neonatal screening receive a new simpler and more readable blotter to facilitate the completion of the requested information. the National Neonatal Screening Program remember, however, that the old blotter can still be used. This levy allows you to:
► Determine the level of phenylalanine: if it exceeds 4 mg/100 ml, the test is positive. A second is then made. If he confirms the diagnosis of Phenylketonuria, medical care is immediately put in place.
► Measure the TSH level: if it is abnormally high, a second test will confirm the disease of congenital hypothyroidism. Therefore, a treatment will be implemented from the 2nd week of life. It consists of taking replacement thyroid hormones.
► Measure the level of progesterone in the blood: if it is abnormally high, the diagnosis of HCS is strongly suspected. It can be confirmed by genetic analysis (from a blood test), highlighting the anomaly of the 21-hydroxylase gene, involved in the majority of cases. The screening test makes it possible to make the diagnosis before the dangerous signs of the disease appear. Hormonal treatment known as “substitution” makes it possible to provide the patient with the missing hormones and to slow down the production of the hormones produced in excess.
► Measure the hemoglobin level: if it is between 7 and 9 g/dl, sickle cell disease is suspected. A blood smear to observe the shape of red blood cells, as well as electrophoresis of hemoglobin can confirm the diagnosis.
► Measure immuno-reactive trypsin, a protein produced by the pancreas when it is affected by cystic fibrosis. If the rate is not within the norm, a genetic test confirms the diagnosis. If this is the case, a treatment stimulating the pancreatic enzymes, in order to substitute the pancreas, is put in place.
Thanks to Dr Monique Quillard, general practitioner and pediatrician.
