Page 219 - Concise Pathology for Exam Preparation ( PDFDrive )

204 SECTION I General Pathology

• Metabolite accumulation: sulfatide.
• The myelin that is synthesized is abnormal, hence affecting the CNS and peripheral
nerves.
• There is mental retardation, peripheral neuropathy and visceral organ abnormalities.
• Krabbe disease
• Enzyme deficiency: galactosylceramidase.
• Metabolite accumulation: galactocerebrosidase.
• Similar to metachromatic leukodystrophy, there is synthesis of an abnormal myelin
leading to progressive psychomotor retardation.
• Sections from brain at autopsy reveal multinucleated globoid cells loaded with the
galactocerebroside material.
• Fabry disease
• Enzyme deficiency: a-galactocerebrosidase A
• Metabolite accumulation: ceramide trihexoside
• It is characterized by angiokeratomas on the skin, hypertension and renal failure
(X-linked recessive disease)
• Mucopolysaccharidoses
• Mucopolysaccharides form a part of the ground substance synthesized by connective
tissue fibroblasts, a certain fraction of which is degraded within lysosomes.
• Mucopolysaccharidoses is characterized by accumulation of mucopolysaccharides
due to lack of certain enzymes involved in their catabolic pathway.
• Several clinical variants (MPS I to MPS VII) are known.
• Two well-recognized syndromes belonging to this category:
• Hurler syndrome (part of MPS I)
- Enzyme deficiency: a-L-iduronidase.
- Metabolite accumulation: dermatan sulphate and heparin sulphate.
- Patients have severe mental retardation, coarse facial features, massive hepato-
splenomegaly, clouding of the cornea, a high incidence of coronary disease
owing to accumulation of the metabolites in the coronary vessels, joint stiffness
and vacuoles in leukocytes in the peripheral blood.
• Hunter syndrome (part of MPS II)
- X-linked inheritance
- Enzyme deficiency: L-iduronate sulfatase
- Metabolite accumulation: dermatan sulphate and heparin sulphate
- Absence of corneal clouding and a milder course differentiates it from Hurler
syndrome

Q. Write briefly on glycogen storage diseases or glycogenoses.
Ans. Principal groups of glycogenoses are given in Table 8.2.

Q. Enumerate the different teratogens and write briefly on their
effects.

Ans. Teratogens may be classified as follows:
1. Noninfectious teratogens
(a) Alcohol: Fetal alcohol syndrome occurs in the offspring of women who have more
than 4–6 drinks per day. It results in intrauterine growth retardation, maxillary
hypoplasia, mental retardation, microcephaly, atrial septal defects and hypoglycae-
mia at birth.
(b) Smoking: Associated with low birthweight and sudden infant death syndrome,
smoking can lead to spontaneous abortions and placental abnormalities.
(c) Cocaine: Cocaine can cause abruptio placentae and premature labour in the mother
and CNS infarcts, intraventricular haemorrhage, genitourinary and gastrointestinal
abnormalities in the newborn.
(d) Isotretinoin: Used to treat acne; it may induce craniofacial abnormalities (small
ears, micrognathia and cleft palate), cardiac defects and CNS malformations
(microcephaly).

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