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To date, 7 cases of GCM have been described in the world literature and all patients are female with no known parental consanguinity.

GCM is a congenital disorder in which patients present with a stocky body build, normal intelligence, coronal craniosynostosis, facial dysmorphism (brachy/turricephaly, low anterior and posterior hairline, coarse hair, synophrys, depressed supraorbital ridges, short and downslanted or upslanted palpebral fissures, ectropion of lower eyelid, underdeveloped ala nasi, prominent columella, midface hypoplasia, and underdeveloped small ears with increased posterior angulation), conductive hearing loss, ocular (coloboma of the eyelid (see this term), hyperopia, microphthalmia) and oro-dental (microdontia, irregularly shaped widely spaced teeth, oligodontia (see this term), narrow, and high arched narrow palate with medial cleft) anomalies and generalized hypertrichosis. Anomalies of the extremities (hypoplastic distal phalanges, small/aplastic nails, cutaneous syndactyly, absent flexion crease of the thumbs, single transverse palmar creases), umbilical hernia, and hypoplasia of labia majora are also observed. Other additional features that may be observed include congenital laryngomalacia and heart disease (patent arterial duct) (see these terms). Progeroid syndrome, Petty type and Saethre-Chotzen syndrome (see these terms) have overlapping features with GCM syndrome and should be considered in the differential diagnosis.

The etiology is still unknown and, to date, no causative gene has been implicated in the physiopathology of GCM.

GCM is considered to be inherited in an autosomal recessive manner. However, the lack of consanguinity combined with the fact that all affected patients are female could suggest a de novo X-linked dominant disorder with male lethality.