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Review
. 2006 Dec 12:1:50.
doi: 10.1186/1750-1172-1-50.

KBG syndrome

Francesco Brancati  1 , Anna Sarkozy, Bruno Dallapiccola
Affiliations
Review

KBG syndrome

Francesco Brancati et al. Orphanet J Rare Dis. .

Abstract

KBG syndrome is a rare condition characterised by a typical facial dysmorphism, macrodontia of the upper central incisors, skeletal (mainly costovertebral) anomalies and developmental delay. To date, KBG syndrome has been reported in 45 patients. Clinical features observed in more than half of patients that may support the diagnosis are short stature, electroencephalogram (EEG) anomalies (with or without seizures) and abnormal hair implantation. Cutaneous syndactyly, webbed short neck, cryptorchidism, hearing loss, palatal defects, strabismus and congenital heart defects are less common findings. Autosomal dominant transmission has been observed in some families, and it is predominantly the mother, often showing a milder clinical picture, that transmits the disease. The diagnosis is currently based solely on clinical findings as the aetiology is unknown. The final diagnosis is generally achieved after the eruption of upper permanent central incisors at 7-8 years of age when the management of possible congenital anomalies should have been already planned. A full developmental assessment should be done at diagnosis and, if delays are noted, an infant stimulation program should be initiated. Subsequent management and follow-up should include an EEG, complete orthodontic evaluation, skeletal investigation with particular regard to spine curvatures and limb asymmetry, hearing testing and ophthalmologic assessment.

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Figures

Figure 1
Figure 1
Frontal (a) and lateral (b) view of a KBG patient with typical facial dysmorphisms including low frontal hairline, wide eyebrows with mild synophrys, hypertelorism, prominent and high nasal bridge, anteverted nostrils, long philtrum, thin upper lip and prominent anteverted ears. Macrodontia of upper central incisors is observable.
Figure 2
Figure 2
Macrodontia of upper central incisors is a constant feature of KBG syndrome (a). Fusion of upper and lateral right incisors is evident in this other patient on physical (b) and panorex film (c) examination.
Figure 3
Figure 3
Common skeletal defects observed in KBG syndrome include supernumerary cervical rib (a, arrow), schisis of the posterior arch of cervical (b, arrow) and/or sacral (c, arrow) vertebrae. Left hand X-ray of a 10-year-old male KBG patient (d) showing shortened tubular bones especially of the III-IV-V metacarpus, the I distal and the V middle phalanges with clinodactylous V finger. Bone age is delayed in particular with respect to carpal bones.
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