What does ketonuria mean

Ketonuria is the most obvious manifestation of high urine ketones. Patients with this disease are generally children, and most of them are caused by genetic factors. It is a chromosomal genetic disease. Whether it is a dominant genetic disease or a recessive genetic disease, it may appear in children. Generally, children will be screened for this disease after birth. So what does ketonuria mean?

1How is phenylketonuria inherited?

Phenylketonuria in children is a common autosomal recessive genetic disease caused by enzyme deficiency in the phenylalanine metabolic pathway. Both parents have chromosomal defects but are asymptomatic. The incidence rate is high among children of close relatives. The child is normal at birth. After drinking milk, symptoms usually appear at 3-6 months old, and become obvious at 1 year old. This disease has been included as one of the routine screening items for newborns in obstetrics.

In summary, phenylketonuria is an autosomal recessive inheritance, and the mutant gene is located on the long arm of chromosome 12 (12q24.1). A slight mutation in this gene can cause the disease, and it is not due to gene deletion. It is a genetic disease caused by the marriage of two heterozygotes. It is more common in the offspring of close relatives, and about 40% of the affected children's siblings are affected. To date, more than 400 PAH gene mutations have been discovered, including deletions, missense mutations, nonsense mutations, synonymous mutations, etc., and more than 70 gene mutations have been found in the Chinese population.

After reading the relevant content of this article, I believe that everyone will have a better understanding of what kind of disease phenylketonuria is and how it is inherited.

2What is phenylketonuria

Phenylketonuria is a common amino acid metabolic disease caused by enzyme defects in the phenylalanine metabolic pathway, which prevents phenylalanine from being converted into tyrosine, resulting in accumulation of phenylalanine and its ketoacids and their massive excretion in the urine. The main clinical manifestations are mental retardation, seizures and hypopigmentation. This disease is an autosomal recessive inheritance. The incidence rate varies with race, approximately 1/14,000 in the United States, 1/60,000 in Japan, and 1/16,500 in China.

Phenylketonuria is a congenital metabolic disease caused by chromosomal gene mutation that leads to phenylalanine hydroxylase (PAH) deficiency in the liver, resulting in phenylalanine (PA) metabolism disorders and causing damage to the central nervous system. Abnormal signs of the nervous system are rare, but may include microcephaly, increased muscle tone, abnormal gait, hyperreflexia, fine tremors in the hands, and repetitive limb movements. Due to the lack of melanin, children often have yellow hair, light skin and irises. The urine of children with this disease often has an unpleasant rat-like odor. At the same time, children are prone to eczema, vomiting, diarrhea, etc. Low-phenylalanine diet therapy is currently the only treatment for classic PKU, and the goal of treatment is to prevent brain damage. In addition to dietary therapy, the treatment of atypical phenylketonuria should also include the supplementation of multiple neurotransmitters, such as BH4, multiple neurotransmitters, such as BH4, dopa, 5-hydroxytryptamine, folic acid, etc.

3 Who is susceptible to phenylketonuria

The main hazard is brain damage. Children with this disease are born normal and do not receive special dietary treatment. Symptoms usually begin to appear at 3 to 6 months of age and are most obvious at 1 year old. The disease is mainly characterized by intellectual disability, and may also have symptoms such as abnormal behavior, convulsions, increased muscle tone, etc., which will eventually cause moderate to extremely severe mental retardation and become a heavy burden on families and society. Due to abnormal phenylalanine metabolism leading to insufficient melanin synthesis, the child's hair is yellower and the skin and iris become lighter in color. Since abnormal metabolic products accumulated in the blood are excreted through urine, there is often an extremely unpleasant rat urine smell. In addition, children often suffer from eczema, vomiting, etc.

Phenylketonuria usually does not cause any abnormalities in the neonatal period and early infancy, and symptoms gradually appear with growth and development. Therefore, the disease requires early detection and treatment to avoid irreversible damage to the nervous system. The effect is better if treated within 3 months after birth. The disease can be detected and diagnosed early through newborn screening.

The most important treatment for this disease is diet therapy. Human milk, animal milk and ordinary food all contain high levels of phenylalanine and are not suitable for feeding sick children. A special low-phenylalanine milk powder should be used. The food added later should be mainly low-protein food such as starch, vegetables and fruits, and the serum phenylalanine concentration should always be controlled to maintain at a normal level. This may avoid brain damage and allow normal development of intelligence. Dietary therapy should continue at least until after adolescence. Dietary treatment for this disease is expensive, so it is best to prevent it and avoid consanguineous marriage.