The proband was referred for chromosome analysis when he was 5 years old because of psychomotor delay and unusual facies. He was the latest child of unrelated, healthy parents. The father was 38 and the mother 28 at the time of his birth. He was born after an uncomplicated 39 weeks pregnancy, and normal vaginal delivery. As a newborn the patient had a short period of cyanosis, and showed congenital hypotonia. Weight was 2100 g (<3rd centile), length 45 cm (<3rd centile), head circumference 34 cm (30th centile). In subsequent evaluation, he showed a failure to thrive and slight delay in the acquisitions of motor milestones; the patient was able to sit with 12 months, and could walk of 2 years, first words were spoken at 36 months, nevertheless, he still retains language disorders and early intervention speech-language therapy was initiated. Length, weight and head circumference at 5 years were 99 cm (<3rd centile), 16 kg (15th), and 50 cm (40th centile), respectively. He had submucous CP with bifid uvula, small forehead, hypertelorism and downslanting palpebral fissures. The nasal bridge was broad and the nasal tip was bulbous. He had low set ears, short philtrum, down turned corners of the mouth and micrognathia. The remaining physical examination was notable for widespread tooth decay and dental overlapping. There were no significant limb anomalies, or cardiovascular disorders. CT scan of the brain was normal, electroencephalogram showed no paroxysmal abnormalities. Ophthalmologic examination and thyroid functions were normal. X-ray examination showed that his bone age was 2 years. Family history revealed an older brother with bilateral cleft lip, but further details were not available.
Cytogenetic and molecular cytogenetic analysis
Cytogenetic analysis was carried out on the patient and his parents. The study included peripheral lymphocyte culture by a standard method using a reverse banding technique (RHG banding), and G-banding technique using trypsin. About 0.4–0.8 mL of peripheral blood was incubated in complete lymphocyte culture medium for 72 h. Metaphases were harvested by adding karyomax colcemid solution for 50 min followed by hypotonic KCl (0.075 M) treatment for 20 min and fixation using standard 3:1 methanol and acetic acid fixative [5]. At least 11 metaphases were scored. A high-resolution analysis was done by synchronization using thymidine solution (15 mg/mL) for 16 h before harvesting [5]. Fluorescence in situ hybridization (FISH) was performed on patient’s metaphases obtained from whole blood cultures. Subsequent probes were applied on lymphocyte metaphase spreads prepared from the propositus: centromere 20 specific probe (D20Z1 in 20q11.1, Abbott/Vysis, Wiesbaden, Germany), whole chromosome paint for chromosome 20 (homemade WCP), bacterial artificial chromosome (BAC) clones; RP11-96L6 in 20p11.21, and RP11-116E13 in 20p12.3 [6].