- Letter to the Editor
- Open Access
Phenotip - a web-based instrument to help diagnosing fetal syndromes antenatally
© Porat et al.; licensee BioMed Central Ltd. 2014
- Received: 18 September 2014
- Accepted: 26 November 2014
- Published: 10 December 2014
Prenatal ultrasound can often reliably distinguish fetal anatomic anomalies, particularly in the hands of an experienced ultrasonographer. Given the large number of existing syndromes and the significant overlap in prenatal findings, antenatal differentiation for syndrome diagnosis is difficult. We constructed a hierarchic tree of 1140 sonographic markers and submarkers, organized per organ system. Subsequently, a database of prenatally diagnosable syndromes was built. An internet-based search engine was then designed to search the syndrome database based on a single or multiple sonographic markers. Future developments will include a database with magnetic resonance imaging findings as well as further refinements in the search engine to allow prioritization based on incidence of syndromes and markers.
Many countries have incorporated ultrasound in routine prenatal care for fetal anomaly screening. When multiple fetal anomalies are found, a syndrome is often suspected. Some syndromes have a known genetic background and can be identified by invasive fetal testing with routine karyotyping and/or comparative genomic hybridization (e.g. Edwards syndrome or DiGeorge syndrome). Many others however, require specific gene sequencing or do not have a known genetic origin (such as Noonan syndrome or Fryns syndrome) and cannot be identified by routine genetic screening tests. Accurate prenatal identification or suspicion of a syndrome is therefore important to guide further testing and/or counseling. Given the large number of known syndromes  (over 6000) and a significant overlap in prenatal findings, antenatal differentiation is difficult. The OMIM® (Online Mendelian Inheritance in Man) database , Orphanet , Possumweb  and London Medical Database  are searchable databases that allow links of phenotypic findings with (genetic) syndromes and may help in diagnosing syndromes. None of the database queries, however, include prenatal ultrasound findings (such as echogenic bowel or increased nuchal fold) in the search algorithm. Moreover, as these databases are mainly designed for postnatal use, they give great importance to markers that may not always be present or identifiable in the prenatal stage (such as failure to thrive, microcephaly or neurodevelopmental delay). Finally, these databases deal poorly with marker synonyms. As an example, the search terms “echogenic kidneys” and “hyperechogenic kidneys” yield 15 and 18 syndromes respectively in OMIM® , but only three syndromes are shared by both searches.
The need for a freely available tool, useable in the prenatal period, brought us to design ‘Phenotip’, a free web-based searchable syndrome database, which is based exclusively on sonographic markers.
The Phenotip collaboration is an independent, international association between maternal-fetal medicine specialists with particular interest in prenatal diagnosis and a software engineer. The Phenotip database relies on a hierarchically structured “tree” of antenatal sonographic markers (n = 1140). Parent markers are organized by organ system and grow in resolution with every level of branching (daughter markers). For example, “face” branches into “eyes”, “ears”, “mouth and lips”. “Mouth and lips” then further branches into “lip”, “palate”, “philtrum” and so on. Therefore, each marker has multiple parent and/or daughter markers. Marker synonyms have been defined to avoid confusion (e.g. talipes – clubfoot). Overall, 1140 sonographic markers are available, among them 130 markers have at least one synonym.
Markers are grouped into syndromes based on an extensive literature search. Only markers that were previously described in a peer reviewed publication as part of the antenatal sonographic phenotype of a proven syndrome were included in the database. Each syndrome is defined by its specific daughter markers, but also includes all hierarchically superior parent markers.
When this information was available, we also noted the incidence and inheritance pattern and male/female ratio for each syndrome. Weblinks to relevant overview articles or websites such as OMIM® , Orphanet , Geneva Foundation , Jablonski’s database  and SonoWorld  were added.
Information for each syndrome was registered by one editor, then peer-reviewed by at least one other editor. So far, we have collected literature on 329 of the most common syndromes.
Searching the database
The syndrome database is freely available through a web-based interface at http://www.phenotip.com. Users can search by syndrome name or by a combination of ultrasound markers.
When a specific marker is chosen, the search algorithm automatically includes all daughter markers of the chosen marker. Each level of the hierarchical tree of each specific organ system is thus considered. Choosing a parent marker will increase the sensitivity of the search while choosing a daughter marker will increase specificity. When a sonographic abnormality is not clearly defined, the involved organ can be selected, and hence all downstream markers would be considered. This is, for example, useful in cases of cardiac malformations, where one syndrome may present with a wide variety of heart lesions. Also, non-experienced sonographers might select the affected organ when they are unable to define the exact cardiac pathology.
Markers can either be selected from an expandable hierarchic tree or from a search box. Users can choose to search only syndromes including “all selected markers” or to search syndromes including either “one of the selected markers”, thereby again increasing sensitivity or specificity, respectively.
Differential diagnosis found using 4, 3 and 2 markers from Figure 1
Markers inserted in Phenotip.com
Number of/diagnosis found with Phenotip.com (except Miller-Dieker Sd)
Lissencephaly - Clinodactyly - Polyhydramnios - Face
Lissencephaly - Clinodactyly - Polyhydramnios
Lissencephaly - Clinodactyly - Face
Microcephalic osteodysplastic primordial dwarfism
Lissencephaly - Polyhydramnios - Face
Clinodactyly - Polyhydramnios - Face
Lissencephaly - Clinodactyly
Microcephalic osteodysplastic primordial dwarfism
Lissencephaly - Polyhydramnios
Lissencephaly - Face
5 other syndromes
Clinodactyly - Polyhydramnios
Clinodactyly - Face
16 other syndromes
Polyhydramnios - Face
44 other syndromes
In addition, the database can offer guidance to the sonographer to find additional markers that differentiate between syndromes or genetic anomalies.
As this is a continuously evolving database (syndromes are being added on a daily basis), formal validation of sensitivity and specificity with validation against postnatal diagnosis has not been undertaken yet.
Diagnosis found using prenatal images and corresponding markers from the Fetus.net
Ultrasound markers in Fetus.net
Diagnosis provided in Fetus.net
Macrocephaly, short long bones, polyhydramnios, platyspondily
Hydrops, micromelia, ribs, narrow thorax, calcification of liver, polydactyly of hands
Mega cisterna magna, micrognathia, pulmonary valve stenosis
2 diagnosis including the correct one(1)
Ventriculomegaly, craniosynostosis, prominent forehead, midfacial hypoplasia, macroglossia, renal cyst
Pfeiffer sd type II
Macrocephaly, abnormal profile, polydactyly, sandal gap
Macrocephaly, hypoplastic thoracic cage, platyspondyly, micromelia, brachydactyly, bowed bones, low nasal bridge
Thanatophoric dysplasia type I
Low nasal bridge, trident hands, frontal bossing, rhizomelia, narrow thorax
Narrow thorax, bowed femurs, low set ears, clubfoot, nuchal edema, heart, retrognatia
Kyphoscoliosis, hemivertebra, ribs
Ventriculomegaly, hypoplastic cerebellum, agyria
Flat nose, exophtalmia, cleft in soft palate, periventricular calcification, hypoplastic thoracic cage
Cloverleaf shape, broad big toe, low nasal bridge, prominent eyes
3 diagnosis including the correct one(2)
Polydactyly of hands and feet, Rhizomelia/short femur and humerus, Ventricular septal defect
Ellis van Creveld sd
Sacral agenesis, meningocele
Depressed nasal bridge, frontal bossing, mitten deformity, corpus callosum
Hydrops, elbow pterygia, micrognathia
Multiple pterygium sd
Polydactyly of hands, micromelia, hypoplastic thoracic cage
Short rib polydactyly
Face, holoprosencephaly, anophtalmia, cleft lip
Abnormal profile, hydramnios, single umbilical artery, micrognathia
Treacher Collins sd
Soft tissu and bone hypertrophy, skin hemangiomas
Postaxial polydactyly of toes, ascites, hydrometrocolpos
Skin, corpus callosum, cleft of soft palate
Hydramnios, micromelia, narrow thorax, short ribs, hepatomegaly
Rhizomelia/short femur /short humerus, postaxial polydactyly, ASD, Hypoplastic thoracic cage
Ellis-Van Creveld sd
Hydrops, barrel shape chest, omphalocele, micromelia
Achondrogenesis type I
Kyphoscoliosis, neural tube defect, ventriculomegaly
Polyhydramnios, small/collapsed stomach, (previous hepatomegaly & IUD)
Gaucher type II
4 diagnosis including the correct one(3)
Micrognathia, Mesomelia forearms, Hypoplastic thumbs
Hydramnios, akinesia, talipes, face, hands
Cloverleaf skull, vertebral body, broad big toes, broad thumbs, prominent eyes
Pfeiffer sd type II
Cloverleaf skull, micromelia, hydrocephalus, exophtalmia, hypoplastic thorax
Thanatophoric dysplasia II
Abdominal wall, ectopia cordis
Pentalogy of cantrell
IUGR, generalized edema, single umbilical artery (SUA)
Hypertelorism, dandy walker, dilated aorta, pulmonary valve stenosis, rocker bottom foot, clinodactily, pectus excavatum, SUA
Hypospadia, nasal bone hypoplasia, micrognathia
Clubfoot, limbs, sacrum
Atelosteogenesis type II
Coarctation of aorta, unilateral hypoplasia of cerebellum, hemangioma
Thick placenta, IUGR, anhydramnios/oligohydramnios
2 diagnosis including the correct one(4)
IUGR, polyhydramnios, increased NT, kydneys, broad thumbs, short long bones
Rubinstein Taybi Syndrome
Holoprosencephaly, pectus excavatum, clenched hands, akinesia
Holoprosencephaly-fetal akinesia sequence
5 diagnosis including the correct one(5)
Hydrocephalus, thin upper lip, mega cisterna magna, extremities
5 diagnosis including the correct one(6)
Polyhydramnios, nuchal thickening, micrognathia, poor ossification of ribs, receding forehead
Micrognatia, renal hypoplasia, IUGR
Skin hemangiomas, renal
Klippel Trenaunay Weber sd
Choroid plexus cyst, limbs, clenched hands, overlapping fingers, clubfoot, nuchal thickening
Pena Shokeir sd
2 diagnosis including the correct one(7)
Short limbs, overlapping fingers, clinodactyly, hypoplastic kidneys, ventriculomegaly, heart
Smith Lemli Opitz sd
Omphalocele, bladder extrophy, neural tube defect, clubfoot
Oligohydramnnios, heart, micrognathia, placenta, sandal gap
Finally, the database is already designed to incorporate the relative frequency of each marker in each specific syndrome, so in the future the search will have even greater specificity and will use a Bayesian approach.
We here describe the development of a searchable database of fetal syndromes. In contrast to other (commercially) available databases, this database only relies on antenatally diagnosable markers and does not include often subtle, postnatal findings.
We feel that this database may help both more and less experienced sonographers, obstetricians, geneticists and fetal medicine specialists in reaching the diagnosis of a fetal syndrome antenatally. Indeed, medicine involves large amounts of data that usually have to be exploited jointly. Given the limitations of the human brain, complex mathematical algorithms or Bayesian networks , integrating all available information can obtain better diagnostic accuracy.
Computer assisted diagnosis is already put in clinical practice on a daily basis in other branches of obstetrics and gynecology. Examples of this include prenatal screening for trisomy 21 , outcome prediction of pregnancies of unknown location  and discriminating between benign and malignant ovarian masses .
This database certainly does not replace expert fetal care providers as it still requires the input of accurate findings and will often only generate a differential diagnosis, which then needs to be explored further. Moreover, dealing with computed knowledge and software as tools for diagnosis does not substitute communication skills and empathy when facing patients.
This project is a work in progress and the number of syndromes included in the database will be further updated. Future developments will include the addition of magnetic resonance imaging markers  as well as further refinements in the search engine to allow prioritisation based on incidence of syndromes and markers. Moreover, we will add postnatal findings and information to each syndrome.
We anticipate that the growing use of advanced technologies (such as chromosomal microarray  or exome sequencing ) for the prenatal diagnosis of genetic alterations that are associated with sonographic abnormalities will discover novel, currently unknown, syndromes. This will further enhance the linkage between specific sonographic findings and the concomitant genomic alteration. As data gathers, we will incorporate those novel syndromes and information into the database. With this database, we hope to facilitate antenatal diagnosis of fetal syndromes and improve patient care.
These data were presented at:
32sd International Fetal Medicine and Surgery Society (IFMSS), Jerusalem, Israel - May 19-24, 2013 (oral presentation)
13th World Congress in Fetal Medicine, Fetal Medicine Foundation, Nice, France, June 29th – July 3rd, 2014, (poster presentation)
We thank Dan Porat for his contribution with the technical aspects of the Phenotip database and search algorithm. We thank Sam Vasilevsky, Karine Lepigeon and Françoise Damnon for critical review of the manuscript.
David Baud is supported by the “Fondation Leenaards” through the “Bourse pour la relève académique”.
Tim Van Mieghem is supported by the Clinical Research Fund (KOF/KOOR) of the University Hospitals Leuven, Leuven, Belgium.
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