A metabolic disorder is a disorder that negatively alters the bodys processing and distribution of macronutrients, such as proteins, fats, and carbohydrates. Metabolic disorders can happen when abnormal chemical reactions in the body alter the normal metabolic process. It can also be defined as inherited single gene anomaly, most of which are autosomal recessive. Signs and symptoms
Some of the symptoms that can occur with metabolic disorders are lethargy, weight loss, jaundice and seizures. The symptoms expressed would vary with the type of metabolic disorder. There are four categories of symptoms: acute symptoms, late-onset acute symptoms, progressive general symptoms and permanent symptoms. Causes
Inherited metabolic disorders are one cause of metabolic disorders, and occur when a defective gene causes an enzyme deficiency. These diseases, of which there are many subtypes, are known as inborn errors of metabolism. Metabolic diseases can also occur when the liver or pancreas do not function properly. Types
The principal classes of metabolic disorders are:

Diagnosis
Metabolic disorders can be present at birth, and many can be identified by routine screening. If a metabolic disorder is not identified early, then it may be diagnosed later in life, when symptoms appear. Specific blood and DNA tests can be done to diagnose genetic metabolic disorders.The gut microbiota, which is a population of microbes that live in the human digestive system, also has an important part in metabolism and generally has a positive function for its host. In terms of pathophysiological/mechanism interactions, an abnormal gut microbiota can play a role in metabolic disorder related obesity.
Pulmonary alveolar microlithiasis (PAM) is a rare, inherited disorder of lung phosphate balance that is associated with small stone formation in the airspaces of the lung. Mutations in the gene SLC34A2 result in loss of a key sodium, phosphate co-transporter (called Npt2b), known to be expressed in distal alveolar type II cells, as well as in the mammary gland, and to a lesser extent in intestine, kidney, skin, prostate and testes. As the disease progresses, the lung fields become progressively more dense (white) on the chest xray, and low oxygen level, lung inflammation and fibrosis, elevated pressures in the lung blood vessels, and respiratory failure ensue, usually in middle age. The clinical course of PAM can be highly variable, with some patients remaining asymptomatic for decades, and others progressing more rapidly. There is no effective treatment, and the mechanisms of stone formation, inflammation and scarring are not known. Signs and symptoms
Patients typically have no symptoms until the third or fourth decade of life. In most cases, the disease is discovered incidentally on routine chest Xray. The most common symptoms include the following:
dyspnea
dry cough
chest pain
sporadic hemoptysis
asthenia
pneumothoraces

Genetics
PAM is hereditary and another involved family member can be identified in 36% to 61% of cases. Impaired activity of the SLC34A2 gene is responsible for PAM.The SLC34A2 gene encodes a membrane protein that is expressed primarily in the apical portions of alveolar type II cells and is the most abundant phosphate carrier in the lungs.