Trigonocéphalie

Trigonocephaly is a congenital condition of premature fusion of the metopic suture (from the Greek , "forehead"), leading to a triangular forehead. The merging of the two frontal bones leads to transverse growth restriction and parallel growth expansion. It may occur syndromic, involving other abnormalities, or isolated. The term is from the Greek , "triangle", and , "head". Trigonocephaly can either occur syndromatic or isolated. Trigonocephaly is associated with the following syndromes: Opitz syndrome, Muenke syndrome, Jacobsen syndrome, Baller–Gerold syndrome and Say–Meyer syndrome. The etiology of trigonocephaly is mostly unknown although there are three main theories. Trigonocephaly is probably a multifactorial congenital condition, but due to limited proof of these theories this cannot safely be concluded. The first theory assumes that the origin of pathological synostosis lies within disturbed bone formation early on in the pregnancy. Causes can either be genetic (9p22–24, 11q23, 22q11, FGFR1 mutation), metabolic (TSH suppletion in hypothyroidism) or pharmaceutical (valproate in epilepsy). The second theory says that synostosis begins when the fetal head gets hindered in the pelvic outlet during birth. The third theory predominates disturbed brain formation of the two frontal lobes as the main issue behind synostosis. Limited growth of the frontal lobes leads to an absence of stimuli for cranial growth, therefore causing premature fusion of the metopic suture. Other conditions and syndromes with trigonocephaly include: Arthrogryposis, cleft palate, craniosynostosis, and impaired intellectual development Atypical glycine encephalopathy Blepharophimosis-intellectual disability syndrome, Verloes type Bohring-Opitz syndrome Coffin-Siris syndrome Greig cephalopolysyndactyly syndrome Holoprosencephaly Mandibulofacial dysostosis-microcephaly syndrome MEGF8-related Carpenter syndrome Microcephaly, primary autosomal dominant Mucolipidosis type II Orofaciodigital syndrome type 14 Paris-Trousseau thrombocytopenia Potocki-Lupski syndrome Simpson-Golabi-Behmel syndrome type 1 Trichothiodystrophy, photosensitive Trigonocephaly-bifid nose-acral anomalies syndrome Diagnosis can be characterized by typical facial and cranial deformities.