A novel MLL2 gene mutation in a Korean patient with Kabuki syndrome
The male patient was born at 40 weeks gestation by spontaneous vaginal delivery to a 27-year-old G0P0 mother and a 29-year-old father. The parents were nonconsanguinous and healthy. The pregnancy and labor were uncomplicated. There was no history of fever, rash, spotting, tobacco, alcohol, illicit drug use, or X-ray exposure during pregnancy. At birth, the patient had microcephaly (<10th percentile) but no anatomical anomalies. He was admitted to a neonatal intensive care unit for 2 weeks due to transient respiratory difficulty. At 18 months of age, he first visited our clinic due to developmental delay. His height, weight, and head circumference were 77.4 cm (10-25th percentile), 11 kg (25-50 th percentile), and 43.4 cm (5-10th percentile), respectively. He could stand up with support at 15 months of age and walked alone at 25 months of age. His speech was delayed and at 27 months of age, he first said "mama". He showed long palpebral fissures with lateral eversion of the lower eyelid, long eyelashes, arched eyebrows with lateral thinning, and a depressed nasal tip. He had brachydactyly and prominent finger pads of bilateral third and fourth fingers. His intelligence quotient was estimated at 53 by Korean-Wechsler Preschool and Primary Scale of Intelligence, which meant moderate mental retardation (0.05th percentile). Spine X-ray showed butterfly vertebra at the 3rd thoracic spine, and echocardiography showed no cardiac anomalies except bicuspid aortic valve. Neurologic examinations showed no abnormal findings. He suffered from recurrent otitis media. At 11 years of age, his height, weight, and head circumference were 131.7 cm (<3rd percentile), 48.6 kg (75-90th percentile), and 55.5 cm (95-97th percentile), respectively. His chromosome was normal, 46, XY, and other laboratory findings including immunoglobulin, insulin, fasting glucose, cholesterol and thyroid hormone (TSH and free T4) were normal.\nAs our patient had typical facial features, skeletal anomalies and postnatal growth deficiency such as height 2 standard deviations, we diagnosed him as KS by clinical findings. After informed consent had been obtained, we performed molecular genetic testing for the MLL2 gene. A novel heterozygous MLL2 mutation (c.5256_5257delGA;p.Lys1753Alafs*34) was identified. However, no genetic mutations were detected in both parents ().