Oral and craniofacial findings in a patient with methylmalonic aciduria and homocystinuria: review and a case report

Abstract

Combined methylmalonic aciduria and homocystinuria (MMA-HC) is a rare metabolic disease characterized by an inborn defect in B12 vitamin metabolism. This case report concerns an 11-year-old patient with MMA-HC, which developed during the neonatal period. The patient shows some of the facial features that were already reported in the literature (high forehead, large floppy, low-set ears, flat philtrum and hypotonia of perioral and masticatory muscles) but no dolichocephalic skull nor long face. The patient also shows signs that had not been previously described: epicanthal folds, broad nasal bridge, long and flat philtrum, amimic expression and, particularly, a postural alteration (the head is rotated and bent towards the left shoulder, which is lower than the right one). Such alteration can be attributed to visual impairment and is responsible for breaking muscular and skeletal balance in the frontal plane, thus causing the horizontal planes of both maxillary bones to converge towards the right--as highlighted by the cephalometric analysis of the Teleradio-graph of the skull in Posteroanterior projection according to Ricketts. As for the patient's teeth, eruption times are normal, but there are anomalies of shape (chisel-like central incisors). As far as dental caries is concerned, the patient's DMFT is 4 (D=4, M=0, F=0). This clinical case highlights the need for dental prevention programs suggested by the pediatrician once the pathology is diagnosed.