Medical Genetics The symptoms of inborn errors of metabolism vary greatly. Each one must be reviewed separately to know what the physical features are Often an infant will show signs of failure to thrive by failing to gain weight, not eating well, and generally showing developmental delay. Vomiting and diarrhea are among other symptoms that may signal the healthcare provider to test for an inborn error of metabolismMedical Genetics The symptoms of inborn errors of metabolism vary greatly. Each one must be reviewed separately to know what the physical features are. Often, an infant will show signs of failure to thrive by failing to gain weight, not eating well, and generally showing developmental delay. Vomiting and diarrhea are among other symptoms that may signal the healthcare provider to test for an inborn error of metabolism