Inherited Metabolic Disorders: PKU, Hypothyroidism, Galactosemia & More

Phenylketonuria (PKU)

Deficiency of the enzyme phenylalanine hydroxylase, necessary for converting phenylalanine into tyrosine.

PKU Treatment

Dietary restriction of protein; patients avoid high-protein foods and artificial sweeteners like aspartame.

PKU in Pregnant Women

If a mother has PKU, she must restrict her protein intake to avoid mental delays in her unborn fetus.

Untreated PKU Symptoms

Developmental delays, seizures, mousy odor, hypopigmentation, and autistic-like behavior.

Congenital Hypothyroidism

Most common and preventable cause of mental delays.

Congenital Hypothyroidism Symptoms

Neonatal jaundice, poor growth, constipation, myxedema, neurological defects, and cretinism.

Congenital Hypothyroidism Screening

Screened with T4 and TSH levels; low T4 and high TSH indicate the condition.

Galactosemia

Deficiency of galactose 1 phosphate uridyl transferase (GALT), leading to the inability to convert galactose to glucose.

Galactosemia Treatment

Lactose/galactose-free diet.

Maple Syrup Urine Disease

Inability to metabolize leucine, isoleucine, and valine due to branched-chain α-ketoacid dehydrogenase deficiency.

Maple Syrup Urine Disease Symptoms

Urine has a sweet smell, lethargy, irritability, and can lead to death within three to seven days after birth.

Homocystinuria

Increased homocysteine due to inability to break down methionine.

Homocystinuria Symptoms

Long limbs and fingers, thromboembolism, scoliosis, ocular lens dislocation, and mental delays.

Cystinuria

Genetic disorder causing recurrent kidney stones, most common in pediatric patients.

Cystinuria Treatment

Lithotripsy, dietary restriction, and maintaining urine pH above 7.5.

Biotinidase Deficiency

Inability to use biotin effectively due to enzyme deficiency, leading to various health issues.

Biotinidase Deficiency Symptoms

Hearing loss, optic nerve atrophy, metabolic acidosis, mental delays, and death within three months.

Congenital Adrenal Hyperplasia

Inborn error of steroid biosynthesis causing lack of cortisol and possibly aldosterone production.

Congenital Adrenal Hyperplasia Screening

Measured by 17 hydroxyprogesterone levels.

Hemoglobinopathies

Screen for HbS for sickle cell and other Hgb variants.

Glucose 6 Phosphate Dehydrogenase Deficiency

Causes neonatal hyperbilirubinemia and chronic hemolytic anemia.

Tyrosinemia Type I

Failure to thrive, renal tubular dysfunction, and developmental delays with a cabbage-like odor.

Cystic Fibrosis

Symptoms include poor growth, respiratory infections, and malabsorption due to abnormal chloride channels.

Cystic Fibrosis Diagnosis

Sweat chloride results over 60 mmol/L are diagnostic.

Albinism

Inherited autosomal recessive condition due to absence of tyrosinase.

Smith-Lemli Opitz Syndrome

Inborn error of cholesterol synthesis causing various developmental issues.

Alkaptonuria

Inborn error of protein metabolism due to deficiency of homogentisate 1,2 dioxygenase.

Alkaptonuria Symptoms

Accumulation of homogentisic acid leading to ochronosis and darkening of urine.