Congenital Malformation Syndrome

What the term means

Birth defects, also called congenital anomalies, are structural or functional differences present at birth. Doctors classify them into a few groups:

A congenital malformation syndrome sits in the second row. Calling something a "syndrome" tells parents and doctors that the different problems are linked, that other hidden problems may be present, and that a shared cause should be looked for.

About 3 in every 100 babies in the US are born with a major birth defect. Most are isolated. A smaller proportion are part of a syndrome.

Common examples

• Down syndrome (trisomy 21): learning disability, characteristic facial features, heart defects in about half, and higher risks of thyroid, hearing and gut problems.
• 22q11.2 deletion syndrome (DiGeorge): heart defects, cleft palate, low calcium, immune problems and learning differences.
• Noonan syndrome: short stature, heart valve problems, a broad neck and distinctive facial features.
• Turner syndrome: girls with short stature, ovarian failure and sometimes heart and kidney defects.
• CHARGE syndrome: eye defects (coloboma), heart defects, blocked nasal passages, growth delay, genital and ear differences.
• Fetal alcohol syndrome: growth restriction, specific facial features and brain effects from alcohol in pregnancy.
• Trisomy 13 and 18: severe multiple malformations, with most babies surviving only a short time.

Causes and risk factors

In many children no cause is found even after full testing. Known causes include:

• Chromosome changes: an extra, missing or rearranged chromosome or piece of chromosome. The risk of some, such as Down syndrome, rises with the mother's age.
• Single-gene variants: a change in one gene, either new in the child or inherited from a parent.
• Exposures in early pregnancy (teratogens): alcohol, some anti-seizure medicines (such as valproate), isotretinoin, and some blood thinners.
• Infections in pregnancy: rubella, cytomegalovirus (CMV), toxoplasmosis, syphilis and Zika virus.
• Maternal health: poorly controlled diabetes and obesity raise the risk of heart and spinal defects. Low folic acid raises the risk of neural tube defects.

Most body structures form between weeks 3 and 8 of pregnancy, often before a pregnancy is known. That is why folic acid and avoiding alcohol and risky medicines matter before conception.

Signs that suggest a syndrome

A doctor is more likely to look for a syndrome when a baby or child has:

• two or more major birth defects, such as a heart defect plus a cleft palate
• one major defect plus several minor features, such as unusual ear shape, wide-spaced eyes or a single palm crease
• growth problems, poor feeding or low muscle tone
• developmental delay, learning disability or seizures
• hearing loss or vision problems
• a family history of similar problems or repeated pregnancy loss

How a malformation syndrome is diagnosed

1. Prenatal screening and ultrasound: blood screening (including cell-free DNA testing) and the anatomy scan at around 18 to 22 weeks can detect many structural defects and chromosome conditions. Amniocentesis or chorionic villus sampling confirms them.
2. Examination after birth: a pediatrician and clinical geneticist examine the child carefully, measure growth and head size, and look for patterns of features.
3. Genetic tests: chromosome microarray is usually the first test for multiple anomalies. Targeted gene panels, exome or genome sequencing follow if needed.
4. Organ screening: echocardiogram, kidney ultrasound, hearing and eye tests, and other investigations depending on the syndrome.

A confirmed diagnosis gives a roadmap: known complications to check for, expected development, and specific treatment guidelines for many syndromes.

Treatment and support

There is no single treatment for a syndrome. Care is coordinated by a team that may include:

• surgeons for heart defects, clefts, gut malformations and other structural problems
• pediatric specialists (cardiology, endocrinology, neurology, gastroenterology)
• feeding specialists and dietitians
• physical, occupational and speech therapists
• early intervention and special education services
• audiology and ophthalmology

Parents are offered genetic counseling, which explains the cause, the chance of it happening again (which can range from very low to 50 percent), and testing options for future pregnancies.

Outlook

The outlook depends on the specific syndrome and the organs involved. Many children with malformation syndromes, such as Down syndrome or 22q11.2 deletion, live into adulthood with good quality of life when complications are treated early. Some syndromes, such as trisomy 18, are life-limiting.

Prevention

Not all syndromes can be prevented, but the risk of some is reduced by:

• taking 400 micrograms of folic acid daily from at least a month before conception
• avoiding alcohol, smoking and recreational drugs in pregnancy
• reviewing all medicines with a doctor before pregnancy
• controlling diabetes before conception
• being vaccinated against rubella before pregnancy
• avoiding infections such as CMV (handwashing after contact with young children's saliva and diapers) and toxoplasmosis (undercooked meat, cat litter)

Frequently asked questions

What is a congenital malformation syndrome?

It is a group of two or more birth defects that occur together because of one underlying cause, such as a chromosome change, a gene variant or an exposure during pregnancy. Down syndrome and fetal alcohol syndrome are well-known examples.

What is the difference between a syndrome and an association?

In a syndrome, the defects share one known cause. In an association, such as VACTERL, certain defects are found together more often than chance would predict, but no single cause has been identified. Both prompt doctors to look for related hidden problems.

Can congenital malformation syndromes be detected before birth?

Many can. Prenatal blood screening, cell-free DNA testing and the mid-pregnancy anatomy ultrasound detect many chromosome conditions and structural defects. Diagnostic tests such as amniocentesis confirm them. Some syndromes are only recognized after birth or in early childhood.

Will it happen again in another pregnancy?

It depends on the cause. Many chromosome changes and new gene variants have a low recurrence risk, while inherited conditions can carry a 25 or 50 percent chance. A genetic counselor can give you a specific risk and explain testing options.