METABOLIC DEFECTS IN AMINO ACID METABOLISM Flashcards
characterized by elevated blood levels of
phenylalanine and phenylpyruvate
Phenylketonuria
If untreated, the disease leads to mental retardation, physical disabilities, and even death
MSUD
caused by a deficiency of phenylalanine hydroxylase
Phenylketonuria
a rare (1:185,000), autosomal recessive disorder in which there is a partial or complete deficiency in branched-chain α-keto acid dehydrogenase
Maple syrup urine disease (MSUD)
refers to a group of conditions in which a defect in tyrosine metabolism results in a deficiency in the production of melanin
Albinism
PKU
Phenylketonuria
Maple syrup urine disease (MSUD) is a rare (1:185,000), autosomal recessive disorder in which there is a partial
or complete deficiency in branched-chain
α-keto acid dehydrogenase
MSUD
Maple syrup urine disease
Phenylketonuria (PKU), is caused by a deficiency of
phenylalanine hydroxylase
an enzyme complex that decarboxylates
leucine, isoleucine, and valine
α-keto acid dehydrogenase
Albinism refers to a group of conditions in which a defect in tyrosine metabolism results in a deficiency in the production of
melanin
most common clinically
encountered inborn error of amino acid metabolism (prevalence 1:15,000)
Phenylketonuria (PKU)
characterized by feeding problems,
vomiting, dehydration, severe metabolic acidosis, and a characteristic maple syrup odor to the urine
Maple syrup urine disease (MSUD)
result in the partial or full absence of pigment from the skin, hair, and eyes
Albinism
characterized by
accumulation of phenylalanine (and a deficiency of tyrosine)
Phenylketonuria (PKU)
They are at increased risk for skin cancer
Albinism
Treatment includes restriction of methionine intake and supplementation with
vitamins B6, B12, and folate
Homocystinuria
appears in different forms, and it may be inherited by one of several modes: autosomal recessive (primary mode), autosomal dominant, or X-linked
Albinism
group of disorders involving defects in the metabolism of homocysteine
Homocystinuria
a rare metabolic condition involving a deficiency in homogentisic acid oxidase, resulting in the accumulation of homogentisic acid
Alkaptonuria
results from a deficiency of copper-requiring tyrosinase, causing a total absence of pigment from the hair, eyes, and skin
Complete albinism
diseases are inherited as autosomal recessive illnesses, characterized by high plasma and urinary levels of homocysteine and
methionine and low levels of cysteine
Homocystinuria
Alkaptonuria has three characteristic symptoms, namely:
homogentisic aciduria large joint arthritis
black ochronotic pigmentation of cartilage and collagenous tissue.
Complete albinism is also known as
tyrosinase-negative oculocutaneous albinism
most common cause of homocystinuria
defect in the enzyme
cystathionine β-synthase, which converts homocysteine to cystathionine
tyrosinase-negative oculocutaneous
albinism is also known as
Complete albinism
Individuals who are homozygous for
cystathionine β-synthase deficiency exhibit
ectopia lentis
skeletal abnormalities
tendency to form thrombi osteoporosis
neurological deficits
displacement of the lens of the eye
ectopia lentis
most severe form of the condition
Complete albinism
