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Deficiency in growth hormone that is either isolated or combined with deficiency in other anterior pituitary hormones.

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There are four types of pituitary dwarfism: Pituitary Dwarfism type I: (Primordial Dwarfism; Sexual Ateleiotic Dwarfism; Isolated Autosomal Recessive Growth Hormone Deficiency Dwarfism) is characterized by sexual ateleiotic dwarfism, hypoglycemia, puppet (baby doll) facies, antibodies to administered growth hormone. It is inherited as an autosomal recessive trait.

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Pituitary Dwarfism type II: (Laron Dwarfism type I; Laron Syndrome; Growth Hormone Receptor Deficiency Syndrome; Growth Hormone Insensitivity Syndrome) is characterized by marked short stature and short limbs. Clinical hyposomatotropism. However, the body proportions in childhood appear normal. In the adult period, the body proportions are childlike. Interestingly, the body proportions are more marked in the stature than head size. There is increased resistance to the action of growth hormone (GH). Occasionally blue sclerae. Other clinical features include hip degeneration, limited elbow extensibility, acrohypoplasia, and high-pitched voice. Distorted sex ratio (19F:2M) in Loja province Ecuador cases. Markedly advanced osseous maturation for height and age. It is believed to be cause by a failure to generate somatomedin (or insulin-like growth factor, IGF1) in response to GH. Normal or increased levels of GH. Growth hormone receptor (GHR) defect. Low IGF1 despite normal or increased levels of GH. It is inherited as an autosomal recessive trait.

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Pituitary Dwarfism type III: (Panhypopituitarism; Ateliotic Dwarfism with Hypogonadism Syndrome; Hanhart Dwarfism; Rigid Cervical Spine Pituitary Hormone Deficiency Syndrome) is characterized by ateliotic dwarfism, multiple endocrine anomalies (hypothyroidism, hypoadrenalism, hypogonadism and panhypopituitarism), neonatal hypoglycemia, and hypoglycemic seizures. Laboratory investigation reveals the presence of sequential loss of anterior pituitary tropic hormones, GH, gonadotropin, thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), and prolactin deficiency. It is inherited as an autosomal recessive trait.

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Pituitary Dwarfism type IV: (Normal Immunoreactive Growth Hormone and Low Somatomedin Pituitary Dwarfism Syndrome; Biodefective Growth Hormone Syndrome; Kowarski Syndrome) is characterized by growth retardation, pituitary dwarfism, and delayed bone age. Normal immunoreactive GH after stimulation, low somatomedin, exogenous human GH responsive, structural abnormality of GH molecule confirmed the diagnosis. It is inherited as an autosomal recessive trait.

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The incidence of types I and II pituitary dwarfism are not known, but panhypopituitary dwarfism is not excessively rare; there are probably 7000 to 10,000 cases in the United States alone.

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Both types I and II pituitary dwarfism are inherited autosomal recessively. The human GHR gene is mapped to 5p13.1-p12. Many cases of panhypopituitary dwarfism are caused by craniopharyngioma and other nongenetic causes. The form inherited as an autosomal recessive or X-linked form is rare.

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There is a defect in the gene encoding GH resulting in either biodefective GH, GH deficiency, or GHR deficiency. The isolated GH deficiency in type I dwarfism may be the result of a defect in hypothalamic releasing factor. Laron syndrome is caused by target resistance to the action of GH.

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