"C" trigonocephaly syndrome: report of a child with agenesis of the corpus callosum and tetralogy of Fallot, and review

Compound heterozygous mutations in the IFT140 gene cause Opitz trigonocephaly C syndrome in a patient with typical features of a ciliopathy

〈 We report on an infant with Opitz trigonocephaly C syndrome (OTCS), who also had manifestations of ciliopathy, including short ribs (non-asphyxiating), trident acetabular roofs, postaxial polydactyly cone-shaped epiphyses, and dysplasia of the renal, hepatic and pancreatic tissues. To investigate the molecular cause, we used an exome sequencing strategy followed by Sanger sequencing. Two rare variants, both predicted to result in loss of functional protein, were identified in the IFT140 gene; a substitution at the splice donor site of exon 24 (c.723 + 1 G > T) and a 17 bp deletion, impacting the first coding exon (c.-11_6del). The variants were confirmed as being biallelic using Sanger sequencing, showing that the splice variant was inherited from the propositus mother and the deletion from the father. To date, Mainzer-Saldino syndrome, Jeune syndrome, and a form of nonsyndromic retinal dystrophy, have been identified as ciliopathies caused by IFT140 mutations. We provide the first description of an OTCS phenotype that appears to result from IFT140 mutations. The presentation of this patient is consistent with previous reports showing that OTCS already exhibited skeleletal and nonskeletal features of a ciliopathy.

Mortality and pathological findings in C (Opitz trigonocephaly) syndrome

Even as a rare multiple congenital anomalies/mental retardation syndrome, the C-syndrome (CS, or Opitz C-trigonoecephaly syndrome) is, at long last, beginning to attract attention because of its developmental and causal complexity. Also, the possibility that the apparently balanced translocation recently described in an affected Japanese boy may soon provide a molecular/causal insight into this disorder. The manifestations recorded in the previously published patients, those autopsied within recent years, and the unpublished instances in our files suggest that the CS is a heterogeneous genetic disorder, predominantly sporadic but with sufficient familial cases (at times with consanguinity) to allow postulation of an entity due to autosomal dominant mutations with a high rate of germinal mosaicism, or due to both autosomal dominant mutations and an autosomal recessive genocopy. In any event, elucidation of cause and pathogenesis of CS will, in due time, shed light on its developmental pleiotropy, rarity in liveborn infants, prevalence in stillborn fetuses, recurrence risk in humans, and occurrence in other animals (e.g., mice) to further understanding of pathogenesis.

Opitz “C” trigonocephaly-like syndrome in a patient with terminal deletion of 2p and partial duplication of 17q

A boy with trigonocephaly, cleft palate, multiple minor anomalies, flexion deformities of elbows, cryptorchidism, and severe muscular hypotonia had an unbalanced karyotype with duplication of the distal 17q and deletion of the tip of 2p. This was derived from a reciprocal translocation in the father, 46,XY,t(2;17)(p25;q24). The propositus had some findings observed in patients with distal dup(17q), while trigonocephaly not found in these patients may be associated with the terminal deletion of 2p including the locus of SOX11 gene. It is proposed that the major clinical findings of this patient are consistent with the phenotype characteristic of the Opitz "C" trigonocephaly syndrome.

Trisomy of 3pter in a patient with apparent C (trigonocephaly) syndrome

The C syndrome is a multiple congenital anomaly/mental retardation (MCA/MR) syndrome first described in sibs. The inheritance has been assumed to be autosomal recessive. Several authors have commented that the combination of anomalies found in the conditions suggest an underlying chromosomal anomaly and in a few apparent cases chromosome anomalies have been described. Our patient had findings consistent with the C syndrome and a duplication of 3p by use of subtelomere probes. This shows that new cytogenetic techniques continue to be important in defining the underlying cause of MCA/MR conditions.

Fronto-ocular syndrome: newly recognized trigonocephaly syndrome

We describe an apparently unique disorder, Fronto-Ocular syndrome, present in a mother and her two daughters, and comprising trigonocephaly due to coronal and metopic craniosynostosis, ocular hypotelorism, ocular proptosis and ptosis, epicanthal folds, hypoplastic supraorbital ridges, elevated nasal bridge, thin philtrum, high-arched palate and a narrow bifrontal region. Both daughters have glabellar capillary hemangiomas, a congenital heart defect and mild developmental disabilities. Review of the literature failed to disclose any syndrome with similar findings. It is likely that this disorder represents an autosomal dominant condition, that arose as a new mutation in the mother. Mutational analysis of fibroblast growth factor receptor (FGFR) 1 and FGFR2 failed to identify the molecular basis of the disorder.

Opitz C trigonocephaly syndrome and midline brain anomalies

We describe a child with trigonocephaly, strabismus, upslanting palpebral fissures, nasal bridge hypoplasia, hypertrophic alveolar ridges and large gingivo-labial frenula, short neck, hip "dysplasia," equinovarus deformities, cryptorchidism, atrial septal defect ostium secundum, and severe mental retardation, findings consistent with C syndrome. The patient also had a Dandy-Walker malformation, complete callosal agenesis, and occipital meningocele. These structural defects are independent of the premature closure of the metopic suture, and confirm that midline brain anomalies are part of C syndrome. The hypothesis that the basic developmental defect in this syndrome primarily affects the midline field is supported by the concomitance of other anomalies, such as conotruncal heart defects, omphalocele, and genital anomalies.