American Journal of Medical Genetics 36:196-208 (1990)
The Popliteal Pterygium Syndrome: Report of a New Family and Review of the Literature
Alasdair Hunter Division of Genetics, Childrens Hospital of Eastern Ontario, and Department of Paediatrics, University of Ottawa, Ontario, Canada.
This paper reports on a family with popliteal pterygium syndrome (PPS), which was ascer- tained through a baby with most of the major signs of the syndrome. The mother, who had a repaired cleft palate and toe syndactyly, had been aware that her syndactyly was familial, but her unpreparedness for the birth of a child with PPS led to interest in, and a subse- quent review of, the differential diagnosis and the variable expression of the clinical mani- festations of this syndrome. Upon review, some earlier reported cases were excluded as PPS, and certain ascertainment and report- ing biases that could affect such an analysis were considered.
KEY WORDS: popliteal pterygium, cleft lip/ palate, ankyloblepharon, lip pits, syndactyly, autosomal- dominant inheritance
INTRODUCTION Trelat 118691 is generally credited with the first de-
scription of the popliteal pterygium syndrome (PPS). More than 60 cases have since been reported. The syn- drome is characterized by marked variability in expres- sion, while the occasional family history suggests the possibility of lack of penetrance [Kind, 19701. We have ascertained a family through a severely affected child and her less affected mother. Family history showed several other apparently mildly manifesting gene car- riers. Evidence was sought as to whether sporadic cases represent new mutations of the autosomal-dominant PPS or are a closely related genocopy. The name pop- h e a l pterygium is used in preference to popliteal web simply to avoid confusion that might occur with the abbreviation PWS and Prader-Willi syndrome.
Received for publication April 11,1989; revision received August 25, 1989.
Address reprint requests to Alasdair Hunter, Division of Ge- netics, Childrens Hospital of Eastern Ontario Ottawa, Ontario. Canada K1H 8L1.
o 1990 Wiley-Liss, Inc.
CLINICAL REPORTS Pa tien t 1
The proposita KP (IV-1, Fig. 1) was the first preg- nancy of her 34-year-old mother and 35-year-old father. The pregnancy was unremarkable save for first-trimes- ter nausea and a mild elevation in blood pressure during the last 2 weeks. At birth she weighed 2,620 g, was 48 cm long, and had an OFC of 33 cm. Neonatal cyanosis and grunting were treated with supplemental oxygen and resolved within 24 hr. A number of physical anomalies were immediately apparent.
Her skull was normocephalic with normal sutures and fontanelle. Hair pattern, structure and distribution were unremarkable. The ears were normal in position and shape. There was a slight downward slant of the palpebral fissures and bilateral ankyloblepharon from the midpoint of the lids to the temporal margins (Fig. 2). She had a right cleft lip, lower lip pits, a complete cleft palate, and multiple oral synechiae, which included a connection from the mucosal surface of the upper to the lower lip, from the anterior alveolar ridges to the buccal surfaces, and posteriorly from the upper to lower jaws. Tongue tie was noted. There was some redundant nu- chal skin. There were no cardiovascular or abdominal anomalies. There was mild intracrural webbing and hy- poplasia of the labia majora (Fig. 3 ) . Popliteal webbing was more marked on the right (Fig. 4). Variable skin syndactyly involved the 3rd and 4th fingers of both hands (Fig. 51, the 4th and 5th toes of both feet, and the 2nd and 3rd toes of the left foot (Fig. 6D). There was marked dimpling over the elbows and knees.
The oral and ocular synechiae were severed at 3 days; the cleft lip repaired a t 6 months and the palate a t 14 months. Active physiotherapy resulted in eventual full extension of both legs. Psychomotor development has been normal; some delay in speech noted a t 15 months was attributed to chronic otitis media, for which myr- ingotomy tubes were inserted. There was some early delay in weight gain.
Patient 2 The mother of the proposita (111-l), was a healthy 34-
year-old woman, who had been well aware of the fam- ilys webbed toes. There was a minimal downslant of her palpebral fissures and absent canines. She had been
Popliteal Pterygium Syndrome 197
9. 41, I A Fig. 1. Pedigree of the family showing distribution of anomalies. 0
Cleft lipipalate; 0 Cleft palate; 3 Toe syndactyly; @Mild or by history toe syndactyly; 0 Hand syndactyly; P = popliteal pterygium; A = Ankyloblepharon; S = Syngnathia; W = Excess oral frenula.
born with a cleft soft palate and abnormal gingival webs, which remained. Her feet showed bilateral vari- able syndactyly between the 2nd and 3rd and the 4th and 5th toes (Fig. 6A). The right 2nd and 3rd toenails were partially fused and dysplastic, and the left great toenail had a typical pyramidal skin bridge, which is seen in this syndrome. There was a suggestion of very mild popliteal involvement (Fig. 7). No other anomalies were noted.
Fig. 3. Genitalia of patient 1 showing labial hypoplasia. The mild crural web is not apparent on the photograph.
Patient 3 The maternal grandfather of the proposita (11-1) was a
58-year-old man with emphysema. He had bilateral metatarsus adductus, broad first toes, variable cutane- ous syndactyly of the 1st to 3rd toes and hypoplastic nails (Fig. 6B).
Patient 4 The maternal uncle of the proposita (111-2) had absent
canines, a slight downslant of his palpebral fissures, and abnormal feet (Fig. 6C). The forefoot was broad, with an increased space between the 1st and 2 4 extensive cuta- neous syndactyly of the 2nd and 3rd, and lateral devia- tion of the second toes.
Patients 5 and 6 The status of the 2 children (IV-2 and IV-3) of patient
4 remains uncertain. Both were thought to have mild syndactyly between the 2nd and 3rd fingers, but this was probably not of significance. IV-2 was noted to have
Fig. 2. Facial photograph of patient 1 showing ankyloblepharon, cleft lip and oral synechiae. Fig. 4. Right leg of patient 1 illustrating the popliteal web.
Fig. 5. Hand of patient 1 showing the 3-4 syndactyly
excess gingival frenula, lateral deviation of the great toes, an increased space between the 1st and 2nd toes, very slight syndactyly of the 2nd and 3rd toes, and small toenails (Fig. 6E). IV-3 had no oral signs, while her feet showed similar, but more obvious, changes to those of her brother (Fig. 6F). The children were otherwise nor- Fig. 7. Legs of Patient 2 showing a hint of popliteal webbing
Fig. 6. A. Feet of patient 2 showing the variable 2-3, and 4-5 syndactyly and the typical skin pyramid on the left first toe. B. Feet of patient 3 showing variable 1-3 zygodactyly and broad first toe. C. Feet of patient 4 illustrating 2-3 syndactyly and increased 1-2 interdigital space. D. Feet of patient 1 showing variable bilateral 4-5, and left 2-3 syndactyly. E. Feet ofpatient 5 showing increased first interdigital space, valgus great toes and small nails. F. Feet ofpatient 6 showing increased first interdigital space, valgus great toes, 2-3 syndactyly (greater on right), and small nails.
Popliteal Pterygium Syndrome 199
mal, although there was some question as to the inter- pretation of palpable cords behind the knees; the conclu- sion was that they were normal hamstring tendons.
DISCUSSION Differential Diagnosis
While the fully expressed PPS consists of cleft lip and/ or palate, ankyloblepharon, syngnathia, lower lip pits, and syndactyly, the hallmark is clearly the popliteal pterygium. Unilateral or bilateral popliteal pterygium in the absence of additional anomalies would appear to be very uncommon and is unlikely to be the sole present- ing sign in a patient with PPS. There was only one case of isolated popliteal web among the 56 cases reviewed from the literature (Appendix A). This retarded child was very briefly described and died a t age 6 years [Ko- pits, 19371. At the very least, additional signs may have gone unreported, and the atypical clinical course raises some question as to the actual diagnosis of PPS. Gener- ally, popliteal webbing will be found associated with other anomalies, and as part of one of a number of syndromes that can be readily distinguished.
The multiple pterygium syndromes, as their name implies, are associated with widespread pterygia in- volving the neck, axillae, elbows, intracrural area, knees, ankles, and fingers. They are generally divided into lethal and nonlethal forms; Hall [19841 has ten- atively subdivided the former into 4 subtypes.
The first lethal subtype [Bartsocas and Papas, 19721 includes ankyloblepharon, syngnathia, cleft lip and pal- ate, thumb anomalies and osseous syndactyly. In the past, it has been confused with the PPS [Escobar and Weaver, 19781. However, it can be distinguished by its autosomal-recessive inheritance: generally lethal course, corneal changes, and marked anomalies of the distal limbs. Thus far, lower lip pits do not appear to have been reported, but Cheirif et al.  reported a patient who was alive a t age 9 years. Unfortunately, no photographs were provided, although a similarly af- fected sib had died shortly after birth.
The remaining lethal subtypes exhibit more severe and diffuse involvement and are distinguished by the gestational stage of onset and degree of bony fusions [Hall, 19841. In addition to multiple contractures and skin webs, they have apparent hypertelorism, edema, cystic nuchal mass, loose skin, and lung hypoplasia.
Most nonlethal familial cases of multiple pterygium phenotype are autosomal-recessive [J