in Arial size 3

General Note: this is one of a series of illustrated "Med-Word Overviews" on Medical Semiology with emphasis on Clinical Dysmorphology and illustrated by images of individuals with Down Syndrome (DS). Aspects concerned with medical parlance and definition of terms and concepts are given in related overviews and in links provided in the left column. The icons given below illustrate general features. Access to fuller views and additional comments are gained by clicking on the icons. 

DS Note: dysmorphic signs more common in individuals with DS that in the general populations. No symptom nor sign is pathognomonic of DS, except prehaps the laboratory proof of trisomy for chromosome 21 in an infant with dysmorphic features. Some 3% of instances of DS are not due to trisomy 21 but to other chromosomal anomalies which may be associated with high recurrence risks ( chromosome 21/21 translocations pose a nearly 100% recurrence risk).   

This is Arial 3 but appears smaller The ancients did not recognize DS from other categories of "cretins". Some 150 years ago, students of "cretinism" named a subcategory as "Furfuraceous, Mongolism, Kalmuk, or Micromicria". In 1959, with the advent of human chromosome analysis, it became clear that "Mongolism" was associated with trisomy for chromsome G or 21. The label Trisomy 21 syndrome is used when a clinical diagnosis is sustained by cytogenetic studies, but has not become popular. Instead, some 20 years ago, the term "Down syndrome" was proposed to replace the offensive label "Mongolism", a nomenclature mutation that appears to be the most popular. Regretably "Micromicria" which accurately places stress on the characateristic smallness of ears, nose, digits and other distal structures notable in DS individuals has not gained favor.

 Down syndrome (DS)  or formerly "Mongolism" can be visually recongnized by professionals and lay persons with "prepared eyes" by exposure to depictions or instances of the syndrome. Most signs (or stigmata) of DS are facial and sufficiently typical to entretain the diagnosis. Among the most consistent, salient but unspecific stigmata are:
> Micromicria;      reduced body size (microsomia), reduced head size (microcephaly) 
> Acrodysplasia;  small, dysmorphic or malformed distal structures (ears, digits ...)
> Hypotonia;         head lag, open mouth, ("rag like baby")   
> Tongue;              thrusting, protruding, drooling 
> Delayed intellectual / motor development

The natural history is often typical (but unspecific) of DS 
 > at birth; reduced head and body size and hypotonia (floppy baby)
 > infancy; discovery of internal malformations (cardiac, intestinal, ...) 
 > childhood; hearing loss, delayed development and intellectual defficits 
 > adulthood; diabetes ...   premature aging, senility, dementia  
>  predictable "complications" provide a basis for age specific anticipatory care protocols
    summarized in http://www.ibis-birthdefects.org/start/dsfact.htm  

Some infants with DS may have more sublte signs ... parents my have difficuties "accepting" prognostic implications (genetic counseling) ... note above a minimal upward palpebral fissures slant, a small nasal tip, an open mouth ... (click for additional vistas and comments)	Note the upward slant of the palpebral fissures, flat face (nasal bridge), small nose, open mouth and short neck plus desquamating facial skin scales - ectodernal anomalies are common in DS (cerebrum, skin, hair, teeth ...). In 1848 and 1856, E. Sequin and J. Down described a sub-category of "cretins" they called  "Furfuraceous Cretinism" and "Monogllism". (cont.)

Typical DS  "facies" plus a hint of alternating strabismus, short neck and narrow chest.  (cont.)	Small brachycephalic (flat occiput) head, sparse scalp hair (hypotrichosis), small ear and folded upper helix, "flat" facial profile, small nose, short neck with thick skin folds. (cont.)

Plethoric (high hematocrit levels in DS are common, edematous face (with a hint of icterus - jaundice in DS can be prolonged) and desquamating skin. Several days later, the same infant (for better view open both icons).

sug> open each icon for additional vistas and notes
cont> part 2 of 4  Down syndrome > Semiology > Dysmorphic signs > part 2 of 4