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| Posted: 31 Oct 2010 06:23 PM PDT
Tay-Sach's Disease Definition Tay-Sach's disease (TSD), also known as Hexosaminidase A Deficiency or GM2 gangliosidosis, is a rare inherited metabolic disorder. In this disorder the affected person's body is unable to metabolize lipids that results to its accumulation in the tissues and nerve cells of the brain. Incidence This inborn error of metabolism is primarily found in Ashkenazi Jewish population (Eastern European Jewish ancestry). Cause Tay-Sach's disease (TSD) is an inherited disorder that follows an autosomal recessive pattern. If both parents are carriers (mother and father), the following probability of disorder incidence will occur:
If either the mother or the father is the carrier, any of their children will not have the Tay-Sach's disease but will be carrier.
Pathophysiology Hexosaminidase A is an enzyme necessary for lipid metabolism. This enzyme catalyzes the biodegradation of acidic fatty materials known as gangliosides. Absence of Hexosaminidase A results to accumulation of ganglioside GM2 into the tissues and nerve cells leading to cognitive challenge due to buildup on brain cells and blindness due to deposits on optic nerve cells. Types Infantile TSD Neonates with Tay-Sach's disease develop normally for the first 3 to 6 months of life. As nerve cells swell up with buildup of gangliosides, a persistent mental and physical deterioration occurs. Progressively, the baby will lose the ability to see, hear and move. Muscle atrophy will begin leading to inability to swallow and later paralysis. A red spot at the back of the child's eye will develop. Most children die of pneumonia and cachexia (malnutrition) by age 3 to 5 years. Juvenile TSD This is an extremely rare type of TSD. In Juvenile TSD, the signs and symptoms are observed between 2 to 10 years. Cognitive, motor, speech difficulties (dysarthria), difficulty swallowing (Dysphagia), unsteady gait (ataxia) and spasticity are observed in affected children. The disease progresses more slowly but death usually occurs by the time the child is 5 to 15 years of age. Adult or Late Onset TSD (LOTS) Late Onset TSD (LOTS) occurs in patients between 20 to 30 years of age. This is a rare form of TSD that is frequently misdiagnosed and more often non-fatal. It is characterized by an unsteady gait (ataxia) and a progressive neurological deterioration. Diagnosis
Clinical Manifestations Before 6 months
At about 6 months  cherry red macula at the eye of a child with TSD
By 1 year
By 2 years or more
Management There is no cure for Tay-Sach's disease, however physicians may prescribe medications to relieve pain, manage seizures, and control muscle spasticity. image from beautifulcanvas.org Related posts: |
| Posted: 31 Oct 2010 05:21 PM PDT
Hypocalcemia in Newborns Definition Hypocalcemia is a disorder where there is a lowered blood calcium levels in newborns. It is defined as a total serum calcium concentration of less than 7 mg/dl. It is divided into early onset which occurs in the first 72 hours of life and late onset at about 5 to 10 days of age. Incidence Occurrence of this disorder is about 30% in infants with very low birth weight (<1500 g) and approximately 89% in premature infants. A very high prevalence rate is also noted in infants born with a diabetic mother. Review of Anatomy and Physiology Parathyroid glands are masses of glandular tissues found on the posterior surface of the thyroid gland. The parathyroids secrete parathyroid hormone (PTH) or parathormone which regulates the calcium levels in the blood. PTH is called a hypercalcemic hormone as it acts to increase the serum calcium blood levels. Normal calcium levels in the blood vary with age: (from Saunder's Foundations of Maternal-Newborn Nursing by Murray and McKinney, 4th Ed) Cord = 9-11.5 mg/dl Newborn, 3-24 hours = 9-10.6 mg/dl Newborn, 24-28 hours = 7-12 mg/dl Newborn, 4-7 days = 9-10.9 mg/dl When the calcium levels in the blood drop, the parathyroids release PTH, which stimulates osteoclasts (bone cell destruction) to break down bone matrix and release calcium in the blood. The PTH also stimulates the kidneys and intestine to absorb more calcium. In contrary, the hormone that functions to decrease calcium in the blood (hypocalcemic hormone) is the calcitonin. Calcitonin is produced by the thyroid glands which cause calcium to be deposited in the bones. Pathophysiology Causes Early Onset Hypocalcemia
Perinatal asphyxia (suffocation) or stress could lead to anoxia. Phosphorous is released with anoxia, thus elevating its level. As phosphorous levels rise, calcium levels drop. This may also be related to renal insufficiency, metabolic acidosis and diminished parathyroid hormone secretion.
Preterm babies are at an increased risk of early onset hypocalcemia in the extrauterine life. This may be related to immature parathyroid glands, premature separation of trans-placental supply, diminished responsiveness of target organs to parathyroid hormone, increased calcitonin, poor intake and decreased responsiveness to Vitamin D.
Late Onset Hypocalcemia
This is possible related to malabsorption, renal insufficiency, maternal Vitamin D deficiency or hepatobiliary disease. Vitamin D is needed for the absorption of calcium, without it the body cannot utilize calcium.
Phosphorous and calcium levels are maintained in an inverse proportion to each other in the bloodstream. If phosphorous levels rise, calcium levels decrease. If calcium levels elevate, phosphorous levels drop. If an infant is fed with a phosphate-rich formula or cow's milk tendencies of having a low calcium level in the blood may result. Whole cow's milk has 7 times more phosphate load than breastmilk.
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