Human Genetics and Disorders

It is a genetic trait and can be inherited by children from their parents.

Secondary, acquired or transient lactase deficiency is caused by an injury to the small intestine, usually during infancy, from acute gastroenteritis, diarrhea, chemotherapy, intestinal parasites or other environmental causes.

Haemophilia is a sex-linked recessive disorder.

Mitochondrial neurogastrointestinal encephalopathy syndrome is a rare autosomal recessive mitochondrial disease. Unlike typical mitochondrial diseases caused by mitochondrial DNA (mtDNA) mutations, MNGIE is caused by mutations in the TYMP gene, which encodes the enzyme thymidine phosphorylase.

Sickle-cell disease is a hereditary blood disorder, characterized by red blood cells that assume an abnormal, rigid sickle shape. Sickling decreases the cells' flexibility and results in a risk of various life-threatening complications. This sickling occurs because of a mutation in the haemoglobin gene.

47, XYY is not inherited but usually occurs as a random event during the formation of sperm cells. An incident in chromosome separation during anaphase II (of meiosis II) called nondisjunction can result in sperm cells with an extra copy of the Y-chromosome. If one of these atypical sperm cells contributes to the genetic makeup of a child, the child will have an extra Y-chromosome in each of the body's cells.

The Brugada syndrome is a genetic disease that is characterised by abnormal electrocardiogram (ECG) findings and an increased risk of sudden cardiac death.

 Alloimmune condition refers to a condition when the body gains immunity from another individual of the same species. In erythroblastocis foetalis, some  maternal antibodies pass through placenta and attack red blood cells of the foetus causing anaemia and other life threatening symptoms in the newborn.

Raynaud's phenomenon is a vasospastic disorder causing discolouration of the fingers, toes, and occasionally other areas. This condition can also cause nails to become brittle with longitudinal ridges.

Epidermodysplasia verruciformis is an extremely rare autosomal recessive genetic hereditary skin disorder associated with a high risk of carcinoma of the skin. It is characterized by abnormal susceptibility to human papillomaviruses (HPVs) of the skin.

Vitiligo is a disorder that causes depigmentation of patches of skin. It occurs when melanocytes, the cells responsible for skin pigmentation, die or are unable to function. The cause of vitiligo is unknown, but research suggests that it may arise from autoimmune, genetic, oxidative stress, neural, or viral causes.

X-rays, UV rays, mustard gas, nitrous acid, and formaldehyde are all mutagens - agents that cause mutations in DNA. They can induce various types of DNA damage including base modifications, cross-linking, and strand breaks, which lead to mutations during repair or replication. These are examples of induced mutations (as opposed to spontaneous).

Down's syndrome is a genetic disorder caused by the presence of all, or part of, a third copy of chromosome 21. It was earlier known as Mongoloid idiocy.

It is a genetic defect and also an inherited anomaly. It can't be corrected by prosthetics or mechanical aid.

Multicystic dysplastic kidney (MCDK) is a condition that results from the malformation of the kidney during fetal development. The kidney consists of irregular cysts of varying sizes and has no function. Multicystic dysplastic kidney is the most common type of renal cystic disease, and it is one of the most common causes of an abdominal mass in infants.