Introduction: Congenital metabolic diseases are considered as rare diseases because of their low incidence and their clinical symptoms at onset. Sometimes they can just begin in the neonatal period. Their progressive knowledge and the availability of specific and sensitive biochemical procedures allow us to diagnose many congenital metabolic diseases, which were not recognized some years ago.
Patients and methods: We reviewed the 52 patients with congenital metabolic diseases diagnosed for the last 25 years in our centre, evaluating the clinical presentation, neurological symptoms, complementary exams and clinical evolution.
Results: The mean age at onset of symptoms was 5 days and the mean age at diagnosis was 88 days of age. We considered a first group of 36 patients with inborn errors of intermediary metabolism, in whom hypotonia, weight loss and seizures are the main symptoms. The second group was composed of 8 patients with defective energy metabolism, who showed abnormal respiratory rhythm and hypotonia. Finally, we considered 8 patients with diseases of the complex molecules, who presented with hypotonia and cataracts as common symptoms at onset. The more common neurological symptoms in this period were hypotonia (60%), sensorial deficit (35%) and refractory seizures (23%). The complementary laboratory tests in the first phases of the diseases allowed us to suspect a congenital metabolic disease especially among intermediary and energy defects. EEG registration and CSF samples were important to diagnose some inborn errors of intermediary metabolism. In the first steps, the neuroimaging was less orientative, even if it allow the exclusion of other diseases. More than half of the patients with inborn errors of metabolism with onset in the neonatal period died within the first year of life.
Conclusion: It is really important to suspect these diseases in the neonatal period so as to achieve an early diagnosis and therapy which may reduce the morbimortality.