A 7-day-old male child was admitted to the neonatology department of our hospital on December 30, 2020 due to "eating less, crying less, and moving less for 7 d". The patient was the firstborn child and was delivered vaginally at full term, with a birth weight of 3.75 kg. The Apgar scores at 1, 5, and 10 min after birth were all 10 points. He was provided a reasonable amount of food after birth but had low sucking power, hiccups, and occasional apnea. The mother denied a history of exposure to poisons, chemicals, or radiation and had regular prenatal examinations during pregnancy; no abnormality was found. The parents did not have blood relations. No history of past illness. There was no history of family hereditary diseases. Upon admission examination, the following was observed: Body temperature, 36.8 ℃; heart rate, 128 beats/min; respiratory rate, 34 times/min; arterial blood pressure, 83/46 mmHg; SpO2, 95%; slightly dry skin; poor elasticity; no rash or ecchymosis on the skin; irregular breathing; no obvious dyspnea; trachea in the middle; no abnormal breath sounds heard in both lungs. Examination of the heart and abdomen did not reveal any abnormalities. Neurological examination showed the following: No response after stimulation; the anterior fontanelle measuring 1.0 cm × 1.0 cm that was flat and soft; hypotonia; and an inability to elicit primitive reflexes. A few hours after admission, the child was observed to have frequent apnea neonatorum. Arterial blood gas analysis showed the following: pH, 7.16 (reference range: 7.35–7.45); PCO2, 96 mmHg (reference range: 35–45 mmHg); PO2, 276 mmHg (reference range: 80–100 mmHg); HCO3-, 34.2 mmol/L (reference range: 21.4–27.3 mmol/L); extracellular fluid base excess, 5.5 mmol/L (reference range: -3–3 mmol/L); lactic acid, 0.9 mmol/L (reference range: 0.5–2.2 mmol/L); and blood ammonia, 100 μmol/L (reference range: 18–72 μmol/L). An electroencephalogram (EEG) showed that diffuse low-amplitude irregular 1–6 Hz δ and θ waves and low-amplitude β waves were mixed in the quiet state, and the external stimulation background did not change. The EEG activity voltage was low, which represented a moderately abnormal neonatal EEG. Serum tandem mass spectrometry showed that the glycine concentration was 850.05 μmol/L (reference range: 130–650 μmol/L), and urine organic acid analysis showed no obvious abnormality. CSF glycine levels were not measured. Routine blood test, routine blood coagulation test, myocardial enzyme, C-reactive protein, procalcitonin, liver and kidney function tests, electrolyte assessment, and cerebrospinal fluid and biochemistry tests did not show obvious abnormalities. Head magnetic resonance imaging (MRI) in the neonatal period (aged 7 d old) showed that a myelinated T1 hypersignal was not found in the hind limbs of the bilateral internal capsules or cerebellar dentate nucleus, and no abnormal corpus callosum was found. When the child was 2 mo old, re-examination of head MRI showed that the corpus callosum was smaller than it was on earlier imaging; the bilateral ventricles were full and irregular (more pronounced on the left side); the corticospinal tract, the white matter of bilateral ventricles, and the parietal lobe showed symmetrical high signal intensity on diffusion-weighted imaging; and the apparent diffusion coefficient map showed slightly low signal intensity. The proband has a variant on exon 8, position chr9:6620259G>T, NM_000170.3:c.395C>A, p.(Ser132*) and a variant on exon 18, position chr9:6556173C>T, NM_000170.3:c.2182G>A, p.(Gly728Arg). The p.(Ser132*) variant has been described in one individual in the gnomAD database v3.1.1 (entry: 9-6620259-G-T). Its allele frequency is 0.000006573. It is reported in dbSNP (rs386833576). According to the American College of Medical Genetics and Genomics (ACMG) guidelines, this variation was judged to be a pathogenic variation based on the supporting evidence (PVS1 + PM2 + PM3). In the pedigree analysis, the father of the proband has no mutation at this site, while the mother of the proband has a heterozygous mutation at this site. The variant p.(Gly728Arg) has been reported on ClinVar as likely pathogenic (accession number VCV000580932.2), and it has been described in dbSNP (rs386833542). Its allele frequency in gnomAD database v2.1.1 is 0.000003977. According to the ACMG guidelines, this variation was judged to be a pathogenic variation based on the supporting evidence (PS1 + PM1 + PM2 + PM5 + PP3). By pedigree analysis, the father of the proband has heterozygous variation at this site, while the mother has no variation at this site. The parents of the child are heterozygous, with a normal phenotype, which is consistent with the pathogenesis of autosomal recessive compound heterozygous genetic diseases.