American Journal of Medical Genetics 77:38–42 (1998) Neuropathologic Findings in a Case of OFDS Type VI (Váradi Syndrome) Barbara J. Doss,1* Shruti Jolly,1 Faisal Qureshi,1 Suzanne M. Jacques,1 Mark I. Evans,1,2,3 Mark P. Johnson,1,2,3 Jennifer Lampinen,2 and William J. Kupsky1 1 Department of Pathology, Detroit Medical Center and Wayne State University School of Medicine, Detroit, Michigan Department of Obstetrics and Gynecology, Detroit Medical Center and Wayne State University School of Medicine, Detroit, Michigan 3 Department of Molecular Medicine and Genetics, Detroit Medical Center and Wayne State University School of Medicine, Detroit, Michigan 2 Oral-facial-digital syndrome type VI (OFDS VI) or Váradi syndrome is a rare autosomalrecessive disorder distinguished from other oral-facial-digital syndromes by metacarpal abnormalities with central polydactyly and by cerebellar abnormalities. Histopathologic characterization of the cerebellar abnormalities has not been described previously. We describe the neuropathologic findings in a stillborn, 21-week estimated gestational age (EGA) male fetus diagnosed antenatally with signs of OFDS VI. Autopsy findings included: facial abnormalities, postaxial central polydactyly of the right hand, bilateral bifid toes, and absence of cerebellar vermis with hypoplasia of the hemispheric cortex. Microscopic analysis of the cerebellum demonstrated absence of the subpial granular cell layer and disruption or dysgenesis of the glial architecture. These histopathologic findings suggest that a primary neuronal or glial cell defect, rather than an associated Dandy-Walker malformation, may account for the cerebellar abnormalities in this form of oral-facial-digital syndrome. Am. J. Med. Genet. 77:38–42, 1998. © 1998 Wiley-Liss, Inc. KEY WORDS: cerebellar vermis hypoplasia; neuropathology; oralfacial-digital syndrome type VI; Váradi syndrome INTRODUCTION The oral-facial-digital syndromes (OFDS) are characterized by anomalies of the oral cavity, face, and dis- *Correspondence to: Barbara J. Doss, M.D., Department of Pathology, Hutzel Hospital, 4707 St. Antoine Blvd., Detroit, MI 48201. Received 19 August 1997; Accepted 23 October 1997 © 1998 Wiley-Liss, Inc. tal limbs. At least nine OFDS have been delineated based on clinical manifestations and inheritance patterns [Torriello, 1993], sharing hypertelorism, anomalies of palate, and of hands and feet, including polydactyly, brachydactyly, clinodactyly, or syndactyly [Toriello, 1993]. OFDS VI, also known as Váradi syndrome, is a rare autosomal-recessive disorder, distinguished from other OFDS by the presence of Y-shaped metacarpals with central polydactyly and cerebellar dysgenesis [Váradi et al., 1980; Torriello, 1993]. Previous reports of OFDS VI have concentrated primarily on the clinical and radiologic characteristics and their distinction from other midline malformation complexes rather than on the neuropathologic findings. We report on a case of OFDS VI diagnosed antenatally, with emphasis on the neuropathologic findings. CLINICAL REPORTS Clinical History A 33-year-old, G2P1 woman and a 31-year-old man sought genetic counseling during the current pregnancy because their 21⁄2-year-old, 46,XY son carried the diagnosis of ‘‘OFDS most closely resembling type VI,’’ characterized by an occipital meningocele, DandyWalker malformation, cleft lip and palate, syndactyly of toes and fingers, and Y-shaped proximal phalanges on the third and fourth digits of the left hand. The tibie and fibule were normally developed. The mother’s family history was also notable for hydrocephalus in one paternal cousin, and craniosynostosis and truncal asymmetry and digital webbing in 2 maternal first cousins. Parental consanguinity was not reported. Antenatal ultrasonography obtained at 19.6 weeks of estimated gestational age (EGA) in the current pregnancy documented a small cerebellar vermis and right hand polydactyly. Fetal growth based on morphometric measurements (biparietal diameter, femur length, and head and abdomen circumferences) was consistent with the EGA based on the last menstrual period, and the amniotic fluid volume was normal. The pregnancy was terminated at 21 weeks EGA. Neuropathologic Findings in OFDS VI Pathologic Findings The fetus weighed 420 g, had a crown-heel length of 28.0 cm, crown-rump length of 19.5 cm, and a foot length of 3.6 cm, as well as hypertelorism (inner canthal distance, 1.9 cm; outer canthal distance, 3.8 cm), a prominent frenulum, poorly developed helix of the ears, and a small uptilted nose with a broad flat nasal bridge. The palate was intact. Postaxial polydactyly of the right hand and bilateral bifid great toes were present (Fig. 1A,B). Radiographs demonstrated central polydactyly characterized by a partially formed ‘‘insertional’’-type fourth metacarpal in the right hand, associated with partially formed distal phalanges (Fig. 1C). Bilateral, broad or ‘‘fused’’ first metatarsals were present bilaterally, associated with bifid great toes (Fig. 1D). Other organs, including the heart, were normally situated and grossly unremarkable. Fig. 1. A: Postaxial polydactyly of the right hand. B: Bifid halluces. C: Line drawing of radiograph, right hand, showing central polydactyly characterized by a partially formed, triangular fourth metacarpal associated with partially formed distal phalanges. D: Line drawing of radiograph, right foot, showing broad or ‘‘fused’’ first metatarsals associated with a bifid great toe. 39 Following formalin fixation, the brain was examined and sectioned serially. The cerebral hemispheres were symmetric and the surface was smooth, consistent with gestational age. The corpus callosum was present. The lateral and third ventricles did not appear enlarged, and the deep gray nuclei and hippocampi appeared symmetrical. A large midline gap in the cerebellum was consistent with agenesis of the vermis (Fig. 2A). Microscopic sections were stained with hematoxylin and eosin, and cresyl violet. Sections of the brain stem and cerebellum confirmed agenesis of the vermis (Fig. 2B). Formation of the lateral cerebellar hemispheric cortex appeared delayed (Fig. 3). Although the gestational age was too early for formation of a compact Purkinje cell layer, and for migration of superficial granule cells into the internal granular cell layer to have occurred, the hemispheric cortical region appeared hypoplastic, with nearly complete absence of an external granular cell layer. Molecular and Purkinje cell layers were broad, indistinct, and hypocellular, and immature Purkinje cells were difficult to identify except in a few small foci. The area adjacent to the aplas- Fig. 2. A: The cerebellum demonstrates a large midline gap (right), compared to an age-matched control case (left), consistent with an aplastic vermis. B: A hematoxylin and eosin stained section of the brain stem and cerebellum confirm aplasia of the vermis. 40 Doss et al. remaining processes appeared thin and poorly oriented with respect to the cortical surface (Fig. 4A,B). GFAP immunostaining, largely absent in the cerebellar hemisphere of the control case except for the subependymal zone, was widespread in glial cell bodies and in cell processes in the patient’s cerebellar hemisphere. GFAP immunostaining was observed in the region of the cerebellar cortical plate, in the subjacent white matter, and in paramedian portions of the pontine tegmentum. Neurofilament immunoreactivity was limited to peripheral portions of cranial nerve roots in the patient and the control case. DISCUSSION OFDS represent what some have termed a ‘‘community’’ of syndromes that has in common variable oral and facial abnormalities and polysyndactyly of the hands and feet [Toriello, 1993]. This combination of anomalies was first recognized by Papillon-Léage and Psaume in 1954 [Papillon Léage and Psaume, 1954]. In 1967, Mohr syndrome was classified as OFDS II; since then, subsequently reported ‘‘variants’’ of OFDS I and II have been delineated into at least nine, and possibly as many as 11, OFDS based on clinical manifestations Fig. 3. Cresyl violet-stained section from the cerebellum. Original magnification ×330. A: OFDS VI. Formation of the lateral cerebellar hemispheric cortex appears delayed. The hemispheric cortical region is hypoplastic, with absence of an external granular cell layer (arrow). Molecular (M) and Purkinje (P) cell layers are broad, indistinct, and hypocellular, and immature Purkinje cells are difficult to identify. The area adjacent to the aplastic vermis appears disorganized, and the periventricular germinal matrix layer is hypocellular. B: Aged-matched control case. Note wellformed subpial granular cell layer (arrow) and forming molecular (M) and Purkinje (P) cell layers. tic vermis appeared disorganized, and the periventricular germinal matrix layer was hypocellular. Small clusters of heterotopic immature neurons were present in the periventricular white matter. However, the dentate nuclei appeared normally formed. The basis pontis, inferior olivary nuclei, and cranial nerve nuclei also appeared appropriately formed. The cerebral cortex, hippocampi, basal ganglia, and thalami appeared appropriately formed for gestational age. No evidence of a hypothalamic hamartoma was noted. Immunohistochemical stains were performed on paraffin-embedded sections, using monoclonal antibodies to vimentin (Ventana, Tucson, AZ), glial fibrillary acidic protein (GFAP) (Dako, Carpinteria, CA), and neurofilament protein (Dako). Morphologic findings and the immunostaining patterns were compared to sections from an age-matched normal patient with polycystic kidneys but without evidence of central nervous system malformation. With vimentin staining, there was a marked decrease in the meshwork of glial cell processes in the forming cerebellar cortex, and the Fig. 4. Immunohistochemical staining with vimentin. Molecular layer (M) and Purkinje (P) cell layers are indicated. Original magnification ×500. A: OFDS VI. B: Control case. In OFDS VI there is a marked decrease in the meshwork of glial cell processes in the forming cerebellar cortex, and the remaining processes appear thin and poorly oriented with respect to the cortical surface, compared to the control. Neuropathologic Findings in OFDS VI and inheritance patterns [Sigaudy et al., 1996; Torriello, 1993, Figuera et al., 1993; Gabrielli et al., 1994]. Most OFDS exhibit autosomal-recessive inheritance with the exceptions of OFDS I and VIII, which are X-linked dominant, and recessive, respectively [Toriello, 1993]. OFDS VI is distinguished from the other OFDS by the presence of central polydactyly with a fused or ‘‘Y’’shaped metacarpal and cerebellar hypoplasia. Additional clinical and radiographic findings of OFDS VI have been elaborated in a review of OFDS by Toriello . Similar to our case, intrafamilial variability between affected sibs has also been reported in OFDS VI [Muenke et al., 1991]. Only a few well-documented cases of OFDS VI have been described [Váradi et al., 1980; Münke et al., 1990]. Váradi et al.  described 7 children of an inbred Gypsy family with normal karyotypes who had polydactyly, reduplicated big toes, cleft lip/palate or lingual nodules, and psychomotor retardation. An autopsy on one of these children, a 3-year-old boy, documented arrhinencephaly, and an absent fossa interpeduncularis and cerebellar vermis. Magnetic resonance imaging in 3 additional patients described by Münke et al.  confirmed cerebellar anomalies, specifically hypoplasia/aplasia of the vermis, as a defining characteristic of OFDS VI. The spectrum of central nervous system changes in OFDS VI may include hypothalamic hamartomas in occasional cases [Münke et al., 1990; Stephan et al., 1994]. Stephan et al.  described a 2.5 × 2.2 cm suprasellar mass arising from the hypothalamic region and compressing the optic chiasm in an 8-month-old boy with bilateral central polydactyly of the hands, postaxial polysyndactyly of the right foot, and precocious puberty. A biopsy of the mass showed ‘‘hypercellular neuronal cells consistent with a hypothalamic hamartoma.’’ Subsequent reports have described a range of posterior fossa abnormalities in OFDS VI, including occipital meningocele and posterior fossa subarachnoid cysts [Toriello, 1993], as well as Dandy-Walker anomaly [Stephan et al., 1994]. Because of subtle and sometimes overlapping manifestations, precise classification of individual patients with an OFD syndrome is not always possible. The clinical manifestations of OFDS VI span a spectrum of abnormalities, and intrafamilial variability is not uncommon. In the current case, although several anomalies support a diagnosis of OFDS VI, radiographically the appearance of the central polydactyly is closer to an ‘‘insertional’’ or ‘‘interstitial’’ type than the classic bifid or ‘‘Y’’-shaped metacarpal. Similar insertional central polydactyly was described as a possible distinguishing sign in a case [Cleper et al., 1993] with manifestations of OFDS VI and Pallister Hall syndrome [Bankier and Rose, 1994]. In our case, the discrepancy may also be a function of developmental age, as most of the manifestations of OFDS VI have been described in children rather than immature fetuses, and fetal phenotypes may be different from those found in term infants [Baldwin et al., 1982]. Many manifestations of OFDS VI also overlap with other OFDS and other midline malformation complexes, including OFDS I (Mohr syndrome) [Camera et al., 1994], Pallister Hall syndrome [Bankier et al., 1994; Muenke et al., 1991], hydroletha- 41 lus syndrome [Muenke et al., 1991] and Opitz trigonocephaly (or C) syndrome [Cleper et al., 1993]. Transitional cases similar to those with short-rib polydactyly syndromes have also been reported [Franceschini et al., 1995], which have led some authors to propose a broader categorization of all of these syndromes under the rubic ‘‘oral-facial-skeletal (OFS) syndromes’’ [Neri et al., 1995]. In addition to anomalies of face, feet, and hands, abnormalities of the central nervous system are present in several OFDS, including OFDS I, II, IV, VI, VIII, and XI. Hypothalamic hamartomas have been described in OFDS I and VI; agenesis of the corpus callosum in OFDS I; porencephaly in OFDS I, II, and IV; and cerebral atrophy in OFDS IV. Hydrocephalus was described in some cases of OFDS VIII, and OFDS XI is characterized by retinal abnormalities [Toriello, 1993]. In the present case, the gross and microscopic abnormalities in the central nervous system primarily involved the cerebellum. Absence of the vermis is a component of Dandy-Walker malformation [Friede, 1989], which has been noted in some cases of OFDS VI [Stephan et al., 1994], including the older brother of this patient. However, in addition to aplasia of the vermis, there was an apparent partial loss or failure of development of cerebellar cortical neurons, particularly granule cells, as evidenced by the near total absence of the subpial granular cell layer in medial and lateral portions of the cerebellum. In addition, the normal framework of glial fibers of the developing cortex appeared depleted and disrupted. Although heterotopias or malformed cortex may be seen in cerebellar tissue adjacent to the vermian defect, cases of DandyWalker malformation typically show well-formed cerebellar cortex in the lateral hemispheres [Friede, 1989]. Cases of Dandy-Walker malformation may be combined with hypoplasia or dysplasia of other alar plate derivatives, including the basis pontis and the inferior olivary nuclei, which appeared normally formed in our patient. Therefore, it appears likely that the cerebellar vermian defect present in this patient differs from the defect seen in typical Dandy-Walker malformation. The microscopic finding of a nearly absent superficial granular cell layer raises the question of granule cell loss or aplasia. Aplasia of the cerebellar granular cell layer is rare in man but has been observed in sporadic and familial cases, as well as in infants exposed to irradiation. Internal granular layer aplasia due to an apparent migrational arrest of superficial granular layer cells has been noted in cases of cerebellar atrophy associated with various disorders of intermediary metabolism such as GM2 gangliosidosis, metachromatic leukodystrophy, and others [Friede, 1989]. Granule cell aplasia has been observed in animal models in both experimental (irradiation) and genetic forms. The findings in this case of granule cell aplasia, combined with an apparent defect in glial elements corresponding to the radial glial or Bergmann glial cells, are reminiscent of the pattern of cerebellar abnormalities noted in certain forms of neurologically mutant mice. For example, defects in granule cell migration and Bergmann glial fibers leading to loss of granule cells characterize 42 Doss et al. the homozygous weaver mutant mouse [Rakic et al., 1973a,b; Smeyne and Goldowitz, 1989]. A candidate gene, Girk2, homologous to a human gene localized to the long arm of chromosome 21, was proposed as the causative gene in the weaver mouse [Mjaatvedt et al., 1995; Bandmann et al., 1996]. Loss of dopaminecontaining neurons in the substantia nigra and other nuclei was also observed in weaver mutant mice, suggesting a more widespread neuronal defect [Graybiel et al., 1990], although no definite evidence of cell loss in the substantia nigra was observed in this case. Cerebellar cortical malformation with disturbances of the radial glial architecture also characterizes the reeler mutant, often in association with abnormalities in other brain structures, including facial, cochlear, and olfactory nuclei [Yuasa et al., 1993], and may be related to a genetic deletion on mouse chromosome 5 affecting an extracellular matrix cell adhesion protein [Montgomery et al., 1994; D’Arcangelo et al., 1995]. Although the findings in this patient differ in some particulars from such models, the models suggest possible chromosomal loci or molecular candidates for further investigations in cases of OFDS VI. 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