In the following, “Congenital malformations” describes diseases that are assigned to this category according to ICD-10 (Q00-Q99). The ICD-10 is used for the International Statistical Classification of Diseases and Related Health Problems and is recognized worldwide.
Congenital malformations, deformities, and chromosomal abnormalities
Congenital malformations are abnormalities of an organ or organ system that have occurred prenatally (before birth) or are already established. They may be genetic, occur spontaneously, or be caused by external influences, environmental. 2-3% of newborns in Germany have genetic peculiarities or malformations.The following areas may be affected:
- Nervous system (ICD-10: Q00-Q07).
- Eyes, ears, face, and neck (ICD-10: Q10-Q18).
- Circulatory system (ICD-10: Q20-Q28)
- Respiratory system (ICD-10: Q30-Q34)
- Cleft lip, jaw, and palate (ICD-10: Q35-Q37).
- Digestive system (ICD-10: Q38-Q45).
- Genital organs (ICD-10: Q50-Q56)
- Urinary system (ICD-10: Q60-Q64)
- Musculoskeletal system (ICD-10: Q65-Q79)
- Other congenital malformations (ICD-10: Q80-Q89).
- Chromosomal anomalies (ICD-10: Q90-Q99).
The malformation may be so severe that the viability of the affected person is impaired. Crucial for the development of a malformation is the time at which the child’s development in the womb is disturbed. Since the child’s organs are being formed up to the 12th week of pregnancy (SSW), care must be taken to avoid damaging influences, especially during this period. The mother’s careful and responsible behavior should of course continue until the end of the pregnancy. The development of the brain in particular can be influenced beyond the 12th week of gestation. If an obvious deviation from the norm can be seen in the shape of the body or parts of the body, we speak of deformities, which can be explained prenatally (before birth). They affect the musculoskeletal system. Examples include deformities of the hip, feet, head, face, spine, and thorax (chest). When the wrong strands of DNA are joined together during DNA repair, a chromosomal abnormality occurs, such as trisomy 21, also called a chromosomal mutation. These are clearly microscopic structural changes of the chromosome (structural chromosomal aberrations) such as a deletion (loss of a DNA sequence), insertion (new gain of a nucleic base within a DNA sequence), duplication (doubling of a specific sequence), or even a translocation (change in the location of a chromosomal segment). Chromosomal abnormalities can cause hereditary diseases or tumor diseases. To be distinguished from chromosomal mutations are numerical chromosomal anomalies. These are clearly microscopically visible numerical changes of the chromosome. They result from defective meiosis (division of maturation). Examples of numerical chromosomal abnormalities are aneuploidy, e.g. monosomy (the unique presence of a chromosome that actually exists twice) or trisomy. Polyploidy (e.g. triploidy) is also a numerical chromosomal abnormality.An example of a monosomy is Turner syndrome (synonym: Ullrich-Turner syndrome): girls/women with this peculiarity have only one functional X chromosome instead of the usual two. A trisomy is an extra copy of a chromosome that is normally present in duplicate. More common trisomies are Klinefelter syndrome (XXY) and Down syndrome (chromosome 21 supernumerary). In triploidy, three complete sets of haploid chromosomes (69 chromosomes instead of 46) are present. Triploidy usually results in an abortion (miscarriage).
Common congenital malformations, deformities, and chromosomal abnormalities
- Foot deformities (clubfeet).
- Cardiac vitiations (heart valve defects)
- Hip dysplasia (malpositions and disorders of ossification (ossification) of the hip joint).
- Short stature
- Klinefelter syndrome – a numerical chromosomal aberration (here: aneuploidy) of the sex chromosomes, which occurs only in boys or men, which is manifested mainly by tall stature and testicular hypoplasia (testicles too small ) – caused by hypogonadotropic hypogonadism (hypofunction of the gonads).
- Cleft lip and palate (LKG clefts).
- Maldescensus testis (undescended testis)
- Malformations of the hands and feet – supernumerary, missing or fused fingers or toes.
- Nevus (benign skin/mucous membrane malformations; “mole”/”birthmark“).
- Spina bifida (neural tube defect; “open back”).
- Trisomy 21 (Down syndrome)
- Turner syndrome (synonym: Ullrich-Turner syndrome).
- Cystic kidney disease – occurrence of many cysts (fluid-filled cavities).
Major risk factors for congenital malformations, deformities, and chromosomal abnormalities
Biographical causes
- Genetic burden from parents, grandparents.
- Genetic diseases
- Chromosomal abnormalities
Behavioral causes
- Nutrition
- Malnutrition during pregnancy
- Micronutrient deficiencies – folic acid (spina bifida, cardiac vitiation/heart defects), vitamin B12 (blood formation disorder), iodine (hypothyroidism/underactive thyroid).
- Consumption of stimulants
- Alcohol during pregnancy
- Smoking during pregnancy
- Drug use during pregnancy
Causes related to disease
- Increased blood glucose (blood sugar) of pregnant women during organ development in the 1st trimester (third trimester).
- Infectious diseases during pregnancy – rubella, chickenpox, toxoplasmosis.
Taking medication – only after medical consultation.
- Antibiotics
- Antiepileptic drugs
- Anticoagulants (blood thinners)
- Neuroleptics – benzodiazepines (drugs that have anxiety-relieving, central muscle-relaxing, sedative, and hypnotic (sleep-inducing) effects).
- Sex hormones
- Cytostatic drugs (active substances in oncology/cancer therapy).
Environmental pollution – intoxications (poisonings).
- X-rays during pregnancy
- Noxae, not further specified
Please note that the enumeration is only an extract of the possible risk factors. Other causes can be found under the respective disease.
The main diagnostic prenatal (antenatal) measures for congenital malformations, deformities and chromosomal abnormalities
All pregnant women are entitled to three basic ultrasound examinations:
- Between the 8th and 11th week of gestation (SSW).
- Between the 18th and 21st SSW
- Between the 28th and 31st SSW
Ultrasound can already detect some malformations such as skeletal disorders, spina bifida, cardiac vitias (heart defects), cystic changes of the kidney and dilated cerebral ventricles. However, these ultrasound examinations are not sufficient for a more specific diagnosis of malformations. Upon request or if there is a reasonable suspicion, the following examinations are available as part of malformation diagnosis:
- Nuchal fold transparency measurement by sonography (ultrasound examination) – performed optimally between the 11th and 14th week of pregnancy.
- If the skull is larger than 45 mm, this may indicate the following other chromosomal disorders in addition to Down syndrome: Trisomy 10, trisomy 13 (Pätau syndrome), trisomy 15, trisomy 16, trisomy 18 (Edwards syndrome), trisomy 22, triplo-X syndrome (trisomy X), monosomy X (Turner syndrome), Klinefelter syndrome.
- To detect physical abnormalities (soft markers) as an indication of chromosomal aberrations (deviations):
- 3D ultrasound (three-dimensional imaging of the fetus/unborn child) – ideally between the 12th and 16th week of pregnancy.
- Fine ultrasound (organ ultrasound) – ideally between the 19th and 20th week of pregnancy.
- Screening tests in the context of prenatal diagnostics (PND; prenatal diagnostics): non-invasive molecular genetic prenatal diagnostic tests to determine chromosomal defects.
- Amniocentesis (amniocentesis; time: 15-17 SSW).
Which doctor will help you?
Prenatal diagnostics is performed by the gynecologist in collaboration with doctors of laboratory medicine and human genetics.
