Interstitial 6q25 microdeletion syndrome: 46,XX,del(6)(q25.2q26)

Abstract

Interstitial 6q25 microdeletion syndrome, an interstitial deletion of the long arm of chromosome 6, is a rare disease presenting with characteristic features of intellectual disability, speech impairment, dysmorphic facial features, microcephaly, agenesis or dysgenesis of the corpus callosum, and multiple organ anomalies. This condition was first reported in 1975 by Milosevic and Kalicanin. Here, we describe a female child with interstitial microdeletion of 6q. A 1-month-old girl was admitted to hospital due to poor weight gain. She was the second female child of healthy nonconsanguineous parents. Her family history was negative for neurological disorders, behavioral problems, or congenital anomalies. The pregnancy was uneventful. She was born at 37 weeks of gestation via vaginal delivery and weighed 2,620 g ( 0.4 SD; Apgar, 7-8-9). She was hospitalized for 2 weeks because of meconium aspiration syndrome and was given oxygen and antibiotics. Echocardiography indicated a mild atrial septal defect. After discharge from the previous hospital, her suckling was slow. She had poor weight gain and cyanosis after vomiting. She was then admitted to the present hospital for close investigation. Physical examination indicated dysmorphic features such as sparse hair, hirsutism, long philtrum, highly arched eyebrows, low set ears, brachytelephalangy of the fifth fingers, and hypoplasia of the fifth finger nails (Fig. 1a–e). Chest examination indicated retractive breathing, inspiratory stridor, and systolic murmur on the right side of the sternum. There were no remarkable findings on abdominal, neurological, or ophthalmologic examination. Automated auditory brainstem response test indicated hearing loss. Videofluorograpy for swallowing indicated no gastroesophageal reflux, but direct flow from the oral cavity to the nasopharynx. Although no remarkable findings were observed in the oral cavity, she was unable to suck milk adequately to gain weight. Finally, she was given thickened formula through the nasogastric tube and began to gain weight. Based on her anomalies, a genetic test was conducted after obtaining consent from her parents. Given that G-banding analysis showed deletion in the long arm of chromosome 6 (Fig. 1f), array comparative genomic hybridization (CGH) was conducted. Array CGH with the SurePrint G3 CGH+SNP 4 9 180K microarray (Agilent Technologies, Santa Clara, CA, USA) showed a 10.2 Mb deletion at q25.2-q26 (position, 154242746-164462426; Human GRCh37/hg19; Fig. 1g), which contains a common chromosome region to that mentioned in previous reports. Genetic