Browsing Pathways

Adenine phosphoribosyltransferase deficiency, which is also known as APRTD or APRT deficiency, is a rare inherited inborn error of metabolism (IEM) leading to the recurrent formation of kidney stones. It is an autosomal recessive disorder associated with a mutation in the enzyme adenine phosphoribosyltransferase (APRT). APRT is involved in the nucleotide salvage pathway, which provides an alternative, and energetically more efficient route to nucleotide biosynthesis in humans and most other animals. A defect in this enzyme can lead to the accumulation of the insoluble purine known as 2,8-dihydroxyadenine. In particular, when APRT has reduced or nonexistent activity, adenine accumulates which is then degraded by xanthine dehydrogenase to 2,8-dihydroxyadenine (DHA). 2,8-Dihydroxyadenine is a derivative of adenine which accumulates in 2,8 dihydroxyadenine urolithiasis (kidney stones). Kidney and urinary tract stones can obstruct the urinary tract, resulting in pain and difficulty urinating. If left untreated, the condition can eventually produce kidney failure. APRTD was first diagnosed in 1976. There are two categories of APRTD: type I involves a complete loss of the APRT function while type II involves a partial loss and is mostly found in Japan. APRT deficiency is estimated to affect 1 in 27 000 people in Japan. APRTD is rarer in Europe, where it affects 1 in 50 000 to 100 000 people. A diagnosis of APRTD can be made by analyzing kidney stones or measuring DHA concentrations in urine. APRTD is treatable with regular doses of allopurinol, which inhibits xanthine dehydrogenase activity. APRTD can also be treated with a low-purine diet and a high fluid intake.

Adenine phosphoribosyltransferase deficiency, which is also known as APRTD or APRT deficiency, is a rare inherited inborn error of metabolism (IEM) leading to the recurrent formation of kidney stones. It is an autosomal recessive disorder associated with a mutation in the enzyme adenine phosphoribosyltransferase (APRT). APRT is involved in the nucleotide salvage pathway, which provides an alternative, and energetically more efficient route to nucleotide biosynthesis in humans and most other animals. A defect in this enzyme can lead to the accumulation of the insoluble purine known as 2,8-dihydroxyadenine. In particular, when APRT has reduced or nonexistent activity, adenine accumulates which is then degraded by xanthine dehydrogenase to 2,8-dihydroxyadenine (DHA). 2,8-Dihydroxyadenine is a derivative of adenine which accumulates in 2,8 dihydroxyadenine urolithiasis (kidney stones). Kidney and urinary tract stones can obstruct the urinary tract, resulting in pain and difficulty urinating. If left untreated, the condition can eventually produce kidney failure. APRTD was first diagnosed in 1976. There are two categories of APRTD: type I involves a complete loss of the APRT function while type II involves a partial loss and is mostly found in Japan. APRT deficiency is estimated to affect 1 in 27 000 people in Japan. APRTD is rarer in Europe, where it affects 1 in 50 000 to 100 000 people. A diagnosis of APRTD can be made by analyzing kidney stones or measuring DHA concentrations in urine. APRTD is treatable with regular doses of allopurinol, which inhibits xanthine dehydrogenase activity. APRTD can also be treated with a low-purine diet and a high fluid intake.

Adenosine deaminiase deficiency (immunodeficiency) is an autosomal recessive disease caused by a muation in the ADA gene which codes for adenosine deaminase. A deficiency in this enzyme results in immunodeficiency and a decreased concentration of lymphocytes in blood. Symptoms include diarrhea, severe or recurrent infections, vomiting and early onset in children, infants and newborns. Treatment includes bone-marrow transplants and enzyme replacement therapy.

Adenosine deaminiase deficiency (immunodeficiency) is an autosomal recessive disease caused by a muation in the ADA gene which codes for adenosine deaminase. A deficiency in this enzyme results in immunodeficiency and a decreased concentration of lymphocytes in blood. Symptoms include diarrhea, severe or recurrent infections, vomiting and early onset in children, infants and newborns. Treatment includes bone-marrow transplants and enzyme replacement therapy.

Adenylosuccinate Lyase Deficiency. (Adenylosuccinase Deficiency ; Adenylosuccinate monophosphate lyase deficiency) is a rare autosomal recessive disease caused by a mutation in the ADSL gene which codes for adenylosuccinate lyase. A deficiency in this enzyme results in accumulation of succinyladenosine in plasma, spinal fluid, and urine. Symptoms, which present at birth, include hyptonia, seizures, mental retardation, and encephalopathy. Treatment includes allopurinol.

Adenylosuccinate Lyase Deficiency. (Adenylosuccinase Deficiency ; Adenylosuccinate monophosphate lyase deficiency) is a rare autosomal recessive disease caused by a mutation in the ADSL gene which codes for adenylosuccinate lyase. A deficiency in this enzyme results in accumulation of succinyladenosine in plasma, spinal fluid, and urine. Symptoms, which present at birth, include hyptonia, seizures, mental retardation, and encephalopathy. Treatment includes allopurinol.

Adrenal hyperplasia type 3, also called Congenital adrenal hyperplasia due to 21-hydroxylase deficiency, is caused by a defect in the CYP21A2 gene which codes for Steroid 21-hydroxylase (21-hydroxylase). Steroid 21-hydroxylase catalyzes hydroxylation of 17-hydroxyprogesterone to 11-deoxycortisol in the glucocorticoid pathway from pregnenolone to cortisol. It also catalyzes hydroxylation of progesterone to 11-deoxycorticosterone (DOC) in the mineralocorticoid pathway on its way from pregnenolone to aldosterone. A defect in this enzyme results in accumulation of 17-Hydroxyprogesterone, progesterone and 17a-Hydroxypregnenolone, androstenedione, and testosterone; decreased levels of cortexolone, deoxycorticosterone, aldosterone and cortisol. Symptoms include salt-wasting crises in infancy due to the lack of aldosterone, like spitting, poor weight gain, vomiting, severe dehydration, and circulatory collapse. The high level of testosterone results in virilization and genital ambiguity of female infants.

Adrenal hyperplasia type 3, also called Congenital adrenal hyperplasia due to 21-hydroxylase deficiency, is caused by a defect in the CYP21A2 gene which codes for Steroid 21-hydroxylase (21-hydroxylase). Steroid 21-hydroxylase catalyzes hydroxylation of 17-hydroxyprogesterone to 11-deoxycortisol in the glucocorticoid pathway from pregnenolone to cortisol. It also catalyzes hydroxylation of progesterone to 11-deoxycorticosterone (DOC) in the mineralocorticoid pathway on its way from pregnenolone to aldosterone. A defect in this enzyme results in accumulation of 17-Hydroxyprogesterone, progesterone and 17a-Hydroxypregnenolone, androstenedione, and testosterone; decreased levels of cortexolone, deoxycorticosterone, aldosterone and cortisol. Symptoms include salt-wasting crises in infancy due to the lack of aldosterone, like spitting, poor weight gain, vomiting, severe dehydration, and circulatory collapse. The high level of testosterone results in virilization and genital ambiguity of female infants.

Adrenal hyperplasia type 5 (AH5) also known as Congenital Adrenal Hyperplasia Due to 17 alpha-Hydroxylase Deficiency is a rare inborn error of metabolism (IEM) and autosomal recessive disorder of cortisol and sex steroids synthesis caused by a defect in the CYP17A1 gene which codes for Steroid 17-alpha-hydroxylase/17,20 lyase. These 2 enzymes catalyze pregnenolone and progesterone to their 17-hydroxy forms in steroidogenesis and mediate three key transformations in cortisol and sex steroid synthesis. This disorder is characterized by a decrease in both cortisol and sex steroids and increase in mineralocorticoids. Symptoms of the disorder include mild hypocortisolism, ambiguous genitalia in genetic males or failure of the ovaries to function at puberty in genetic females, and hypertension. Treatments for Hypertension and mineralocorticoid excess is done with glucocorticoid replacement. Genetically female patients need female hormone replacement to induce puberty and regulate menses. Surgery may be needed for males with ambiguous genitalia. Testosterone must be replaced for genetically males (XY) to induce puberty and continued throughout adult life. It is estimated that Adrenal hyperplasia type 5 affects 1 in 1 million individuals worldwide.

Adrenal hyperplasia type 5 (AH5) also known as Congenital Adrenal Hyperplasia Due to 17 alpha-Hydroxylase Deficiency is a rare inborn error of metabolism (IEM) and autosomal recessive disorder of cortisol and sex steroids synthesis caused by a defect in the CYP17A1 gene which codes for Steroid 17-alpha-hydroxylase/17,20 lyase. These 2 enzymes catalyze pregnenolone and progesterone to their 17-hydroxy forms in steroidogenesis and mediate three key transformations in cortisol and sex steroid synthesis. This disorder is characterized by a decrease in both cortisol and sex steroids and increase in mineralocorticoids. Symptoms of the disorder include mild hypocortisolism, ambiguous genitalia in genetic males or failure of the ovaries to function at puberty in genetic females, and hypertension. Treatments for Hypertension and mineralocorticoid excess is done with glucocorticoid replacement. Genetically female patients need female hormone replacement to induce puberty and regulate menses. Surgery may be needed for males with ambiguous genitalia. Testosterone must be replaced for genetically males (XY) to induce puberty and continued throughout adult life. It is estimated that Adrenal hyperplasia type 5 affects 1 in 1 million individuals worldwide.