Case presentation

A seven-year-old boy, presumed case of ataxia-telangiectasia, was referred to our pediatric immunology clinic by a pediatric neurologist for further workup due to ocular involvement. He was born from non-consanguineous parents, gravid four, with a history of developmental delay in the previous child but no history of abortion or death. The proband weighed 3.5 kg at birth (full-term), at which time asphyxia did not occur. At the age of eight months, the parents became concerned about a delay in sitting and standing, but neuroimaging was normal without any evidence of cerebellar or vermian hypoplasia or other anomalies. He developed telangiectasia in the eyes at 15 months of age, at which time vision problems also manifested. He had a delay in global development and speaking; by four years, he could only correctly say one or two words. The convulsion history was negative. Due to his attention disorder, methylphenidate and risperidone were prescribed for him at the age of five.
At seven years of age, he had a weight of 29 kg (+2 standard deviations [SD]), a height of 120 cm (−1 to 0 SD), with a head circumference of 52 cm (−1 SD). Our physical examination revealed slight facial coarseness, mildly deep-set eyes, round nasal tip, full cheeks and thick lips (Fig. 1), central hypotonia, and ataxia. Deafness, ichthyosis, and hand stereotypes were not noted.
Our ophthalmologic consultant reported pigmentary retinopathy with optic disc paleness on examination of the fundus. Telangiectasia and nystagmus were also reported, though ocular coloboma was not seen. The visual-evoked potential demonstrated an extinguished response.
On laboratory workup, routine hematology and biochemical tests (renal/hepatic function) were normal, as were the essential metabolic screening, arterial lactate, and blood ammonia. Interestingly, the insulin-like growth factor (IGF)-1 level was normal Other normal tests included an electroencephalogram, the brainstem-evoked potential, a karyotype study, and chromosomal microarray.
Considering the patient’s clinical manifestations (pigmentary retinopathy, hypotonia, ataxia, and telangiectasia), we suspected congenital disorders of glycosylation (CDG) and requested serum isoelectric focusing and whole-exome sequencing. Exome sequencing identified the presence of homozygous pathogenic variant c.57G>A (p.Trp19Ter) in the SRD5A3 gene. The mutation was confirmed by Sanger sequencing, and the diagnosis of SRD5A3-CDG was established.