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Down Syndrome - Initial Diagnosis
Overview
In August 2011, the American Academy of Pediatrics’ Committee on Genetics published new guidelines for the health supervision of children with Down syndrome. The Portal team is currently updating this module to incorporate these. Until that is complete, please refer to [Bull: 2011] for the updated information.Several distinctive physical characteristics are usually apparent at birth in Down syndrome (DS), particularly features of the face, hands, and feet. Numerous other congenital anomalies occur with increased frequency in DS, such as endocardial cushion defects, intestinal atresias, and Hirschsprung disease
Presentations
When performed, prenatal screening will identify approximately 70-80% of affected fetuses. A European study found that roughly 90% of mothers of affected fetuses opted to terminate pregnancy [Morris: 2009]. The birth of an infant with DS that was not identified prior to birth is becoming less common but will continue to occur. Clinicians ask "does this child have Down syndrome?" when a newborn is noted to have atypical features, hypotonia, or a DS-associated major malformation. An infant's presentation may be subtle, leading to occasional missed diagnoses in the newborn period. These infants are likely to be recognized by the primary care clinician due to poor growth, feeding concerns, developmental delays, hypotonia, or concern for a medical condition associated with DS. Ten percent of individuals with DS are identified after 1 week of age and over half of these not until adulthood. This is more likely when an individual has mosaic trisomy 21, in which physical features may be subtle. Mosaic trisomy 21 has been identified in adult individuals with intellectual challenges who had no physical features of DS.Diagnostic Criteria
While physical features may suggest a diagnosis of DS, confirmation requires chromosome analysis. In the majority of individuals, chromosome analysis will reveal an extra chromosome 21. In 4% of patients with DS analysis will find the attachment of an extra long arm of chromosome 21 to another chromosome (translocation DS). A very small percentage have an extra chromosome 21 in only some of their somatic cells due to nondisjunction during mitosis of the fertilized egg (mosaic DS).Practice Guidelines
American Academy of Pediatrics - Committee on Genetics.
Health supervision for children with Down syndrome.
Pediatrics.
2001;107(2):442-9.
PubMed abstract / Full Text
Driscoll DA, Gross SJ.
First trimester diagnosis and screening for fetal aneuploidy.
Genet Med.
2008;10(1):73-5.
PubMed abstract
Differential Diagnosis
Since many physical features of DS occur occasionally in typical infants, the clinician should look for a constellation of findings when considering the diagnosis. Nevertheless, diagnostic confusion can occur – in one laboratory's review, among blood samples obtained by clinicians to confirm or exclude trisomy 21, 28% had a normal karyotype [Devlin: 2004]. Epicanthal folds, protruding tongue, simian crease, widely-spaced first and second toes, hypotonia, and up-slanting palpebral fissures were physical findings that had raised concern for DS in karyotypically normal infants. Confusing DS with another genetic syndrome is uncommon but can occur, since its features can overlap with other syndromes (e.g., Smith-Magenis syndrome, Noonan syndrome). These issues underscore the importance of genetic testing to confirm diagnosis.History And Examination
Family History
A three-generation pedigree is indicated for any child with a genetic condition. While a family history of Down syndrome or other chromosome abnormality is usually absent, this is important to document. The age of parents of DS babies should be ascertained because the incidence of aneuploidy in offspring increases with parental age, particularly maternal age. Inquire about a family history of pregnancy loss, especially miscarriages, which can suggest a familial translocation. Ask also about immediate relatives with DS, since the condition will recur in 1-2% of families. It is also important to ask about more distant relatives and the presence of other aneuploidy syndromes.Pregnancy/Perinatal History
The pregnancy and perinatal history in an individual with DS may include: abnormal prenatal ultrasounds (e.g., polyhydramnios, suggesting duodenal obstruction, or minor ultrasound findings, such as redundant nuchal skin and increased nuchal translucency), abnormal first and second trimester maternal screening (including the triple screen or first trimester serum screening), and detection of structural defects (including the prenatal diagnosis by ultrasound of cardiovascular malformations or duodenal atresia). The perinatal history is usually uncomplicated in terms of labor management and delivery.Medical History
Because up to 40% of children with Down syndrome have a congenital heart defect, cardiorespiratory symptoms are important. Evidence of hearing impairment, hypothyroidism, or celiac disease may contribute.Developmental and Educational History
The degree and pattern of developmental delay will be important to diagnosis and initial planning.Maturation History
Pubertal development should be expected within the same age parameters as for children without trisomy 21.Social and Family History
The understanding of DS by parents, siblings, and extended family members and their adaptation to the child's special needs should be discussed. In the case of the newly diagnosed infant, it may be helpful to ask family members if they have ever known someone with Down syndrome. This often uncovers preconceived notions about outcomes.Physical Exam
General
In a child with suspected DS, the presence of minor anomalies should be documented at the time they are detected. Because these may contribute to parents' concern about the stigma of DS, reassurance about their presence is important. Common minor anomalies include:- upward-slanting eyes
- inner epicanthal folds
- small upturned nose with saddle bridge
- a protruding tongue that develops fissures with age
- Brushfield spots
- small ears
- short neck with redundant skin folds
- brachycephaly
- flat occiput
- single palmar (simian) crease
- wide space between first and second toes (sandal toes)
- clinodactyly of the fifth finger
Growth Parameters
Height, weight, and head circumference (OFC) should be plotted on typical and DS-specific growth charts.HEENT
Examine the tonsils for hypertrophy, which may contribute to airway obstruction. Look for middle ear effusions, evidence of chronic sinus infection, or poor nasal flow suggesting adenoidal enlargement. Palpate for thyroid enlargement or nodules. Assess extra-ocular movements, ocular alignment, pupil response, and presence of nystagmus. Look for evidence of nasolacrimal duct obstruction or chronic blepharitis.Skin
Examine for dry skin, evidence of skin infection, eczema, thickened skin on palms or soles, vitiligo and alopecia.Chest
Assess for murmurs, abnormalities in the first and second heart sound, or evidence of heart failure.Abdomen
Bloating may be seen in children with celiac disease or chronic constipation. Hepatomegaly may be seen with congestive heart failure.Testing
Sensory Testing
Vision: Assess for strabismus, cataracts, and nystagmus.Hearing: hearing screen should be confirmed normal.
Imaging and EEG
Although not performed routinely, a KUB should be performed in any newborn suspected of having DS who is exhibiting emesis to evaluate for duodenal atresia (double bubble sign). Additional assessment with upper gastrointestinal series (upper GI) and/or barium enema should be considered to assess anatomy in any infant with DS and gastrointestinal symptoms.An echocardiogram should be performed on every child with DS to rule out a cardiac defect.
Genetic Testing
A karyotype performed on lymphocytes confirms suspicion of the diagnosis and is important to clarify which of the chromosome abnormalities (parental nondisjunction of chromosome 21, translocation or mosaicism) is the cause. Studies are done on the parents only if there is a translocation present in the child. Prenatal diagnosis in future pregnancies, either with chorionic villous sampling at 10 weeks or amniocentesis at 15 weeks, is offered. Preimplantation testing is also available to screen blastomeres for aneuploidy and translocations, but the cost is substantial since this process requires in vitro fertilization and ICSI (intracytoplasmic sperm injection).Other Testing
Neuroimaging is not routinely indicated in children with trisomy 21, but should be considered in a child with macrocephaly or microcephy relative to other children with DS (using DS-specific head circumference growth charts - see Tools below), a child whose development seems atypical for a child with DS, and a child who has abnormalities on neurologic examination that can not be attributed to DS.Subspecialist Collaborations and Other Resources
Children suspected of having DS may benefit from evaluation by subspecialists.
Developmental Pediatrics (see Services below for relevant providers)
Particularly helpful for an older infant or child being evaluated for possible DS.
Pediatric Cardiology (see Services below for relevant providers)
All infants with DS should have an echocardiogram. Depending upon sedation needs and the policies of the echo center, this may require referral to a pediatric cardiologist. If abnormalities are found on echo, such referral is advised.
Audiology (see Services below for relevant providers)
All infants should have a newborn hearing screen with appropriate follow-up for abnormal results.
Pediatric Ophthalmology (see Services below for relevant providers)
DS guidelines recommend that all children with DS evaluated by an ophthalmologist by 6 months of age (sooner if eye examination is abnormal).
Pediatric Gastroenterology (see Services below for relevant providers)
May be helpful in evaluating a child with suspected DS who has vomiting, constipation, GERD, dysphagia, poor oral intake, chronic diarrhea, or suspected celiac disease.
Pediatric Medical Genetics (see Services below for relevant providers)
May be very helpful in diagnosis, evaluating recurrence risk and prenatal testing options (particularly in the case of translocation related DS), and counseling the family regarding etiology and outcomes.
Developmental Evaluation (see Services below for relevant providers)
A developmental evaluation service can document the child's current functional abilities as a baseline for diagnosis and future evaluations.
Pediatric Neurology (see Services below for relevant providers)
May be indicated when a child has neurologic findings associated with DS but less commonly seen (e.g., tremor, nystagmus, severe hypotonia), neurologic findings not typical of DS (e.g., spasticity, ataxia), relative microcephaly or macrocephaly (assessed using DS specific head growth curves), or developmental delays beyond those typically seen in this disorder.
Resources
Information & Support
For Professionals
Trisomy 21 (OMIM)
Extensive review of the literature, including clinical features and genetics, from the Online Mendelian Inheritance in Man
site, hosted by Johns Hopkins University, providing technical information for providers on genetic disorders, links to MEDLINE,
and links to other scientific information and sites.
Information for Healthcare Professionals (National Down Syndrome Society)
Physician-oriented information from the National Down Syndrome Society. This website offers a downloadable "Guide for New
and Expectant Parents."
For Parents and Patients
Support
Utah Parent Center
This statewide non-profit organization, founded in 1984, provides training, information, referral and assistance to parents
of children and youth with all disabilities, including physical, mental, hearing, vision, learning, behavioral, and emotional.
Staff consists primarily of parents of children and youth with disabilities. The Center provides information on support and
advocacy for families of children with special health care needs.
National Down Syndrome Congress
The NDSC, a membership organization, offers parent resources, including a "new parent package" of information, as well as
news and events, government activities, and information on self-advocacy.
The International Mosaic Down Syndrome Association
Aims to assist any family or individual whose life has been affected by mosaic Down syndrome.
International Foundation for Genetic Research (The Michael Fund)
Advocacy organization aimed at fund-raising for research, improving care and education of children with DS, and right-to-life
issues.
Utah Down Syndrome Foundation
A non-profit organization, established in 1977, to provide support, training, counseling, and education to individuals with
Down syndrome, their parents, families, and the community. This volunteer organization has 14 chapters throughout the state.
General
Down Syndrome (Genetics Home Reference)
This site, sponsored by the National Library of Medicine, offers a wealth of information and links to more information about
Down syndrome. The information is aimed at consumers/patients/families.
Down Syndrome Issues and Information (down syndrome online)
An extensive series of comprehensive reference resources examining issues for people with Down syndrome from birth to adulthood.
Down Syndrome (MedlinePlus)
From the National Library of Medicine and National Insitutes of Health, offers many links to high-quality sources of information
for patients and their families.
Practice Guidelines
American Academy of Pediatrics - Committee on Genetics.
Health supervision for children with Down syndrome.
Pediatrics.
2001;107(2):442-9.
PubMed abstract / Full Text
Driscoll DA, Gross SJ.
First trimester diagnosis and screening for fetal aneuploidy.
Genet Med.
2008;10(1):73-5.
PubMed abstract
Tools
Down Syndrome Checklist
(
30 KB)
Checklist of recommended screening evaluations through out childhood that can be printed and placed in the patients medical
chart to monitor patient care.
Down Syndrome Growth Charts (Boys, English measures)
( 247 KB)
Printable growth charts for height, weight, and head circumference for children with trisomy 21.
Down Syndrome Growth Charts (Boys, Metric)
( 251 KB)
Printable growth charts for height, weight, and head circumference for children with trisomy 21.
Down Syndrome Growth Charts (Girls, English measures)
( 246 KB)
Printable growth charts for height, weight, and head circumference for children with trisomy 21.
Down Syndrome Growth Charts (Girls, Metric)
( 247 KB)
Printable growth charts for height, weight, and head circumference for children with trisomy 21.
Services
Pediatric Gastroenterology
See all Pediatric Gastroenterology services providers (2) in our database.
Pediatric Medical Genetics
See all Pediatric Medical Genetics services providers (3) in our database.
For other services related to this condition, browse our Services categories or search our database.
Page Bibliography
Bull MJ and the American Academy of Pediatrics Committee on Genetics.
Health Supervision for Children With Down Syndrome.
Pediatrics.
2011;128(2):393-406.
PubMed abstract / Full Text
Devlin L, Morrison PJ.
Accuracy of the clinical diagnosis of Down syndrome.
Ulster Med J.
2004;73(1):4-12.
PubMed abstract / Full Text
Morris JK, Alberman E.
Trends in Down's syndrome live births and antenatal diagnoses in England and Wales from 1989 to 2008: analysis of data from
the National Down Syndrome Cytogenetic Register.
BMJ.
2009;339:b3794.
PubMed abstract / Full Text