X-Linked Disorders

completely on glycolysis for energy so they get hemolyzed more easily. It is autosomal recessive.

· Autosomal recessive polycystic kidney disease—this is less likely to be the case compared to autosomal dominant disease. There are numerous bilateral cysts in the collecting ducts of the kidneys.

· Fanconi’s syndrome type I—this is child-onset cystinosis and is an autosomal recessive kidney disease. It involves cystine deposition in the entire body and cystinuria with defective tubular resorption leading to amino aciduria and chronic acidosis. The patient will have vitamin D-resistant rickets.

· Fanconi’s syndrome type II—this is adult-onset, autosomal recessive renal disease. It is similar to type I disease but does not involve cystinosis. Adults with disease will have osteomalacia, amino aciduria, polyuria, and glycosuria.

· Bartter’s syndrome—this is an autosomal recessive renal disease that results in juxtaglomerular cell hyperplasia and primary hyperreninemia. There is hypokalemic alkalosis, increased renin and aldosterone levels but no hypertension.

X-LINKED DISORDERS

X-linked disorders involve a defect carried on the X chromosome. These are almost exclusively recessive traits. Males have the disease to a much higher degree when compared to women. Female carriers will pass the disease onto half of all boys and will lead to a carrier status in half of all girls. A male with the disease will not pass the disease onto their sons but will lead to a carrier status in all female children.

· Wiskott-Aldrich syndrome—this is an x-linked immune deficiency disease in which there is an inability to mount an IgM response to the capsules of pyogenic bacteria. It leads to increased infections in infancy, thrombocytopenia, excessive bleeding, and eczema.

· Glucose-6-phosphate dehydrogenase deficiency—this is an x-linked recessive disease affecting the enzyme G6PD. It leads to oxidative damage in the RBCs and hemolytic anemia.

· Hunter’s syndrome—this is a lysosomal storage disease that is x-linked and related to L-iduronosulfate sulfatase deficiency, leading to a buildup of mucopolysaccharides. It is less severe than Hurler syndrome but will cause mild mental retardation, micrognathia, and joint stiffness.

· X-linked agammaglobulinemia—this is also called Bruton’s disease and is an immune deficiency disease that affects gene coding for tyrosine kinase so that pre-B cells do not differentiate into B-cells. There will be recurrent pyogenic infections after six months of age when the maternal antibodies are no longer present. It can be treated with gamma globulin preparations.

· Fabry’s disease—this is a lysosomal storage disease that is x-linked and secondary to alpha-galactosidase A deficiency. There are skin lesions, severe burning pain in the extremities, heart problems, and cerebrovascular involvement.

· Chronic granulomatous disease—this is usually x-linked and involves an NADPH oxidase deficiency so that there are no peroxides and super-oxides, leading to a lack of an oxidative burst in the phagocytes. This leads to an increased risk of

Staph infections and other infections even though the T cells and B cells are normal.

· Hemophilia A—this is an x-linked factor VIII deficiency, leading to an increase in hemorrhage, hematuria, and bleeding into the joints. The PTT will be prolonged.

· Hemophilia B—this is an x-linked factor IX deficiency, leading to a milder disease than is seen in hemophilia A but there will still be prolongation of the PTT.