Cryptorchidism, or failure of testicular descent, is a common human congenital abnormality with a multifactorial etiology that likely reflects the involvement of endocrine, environmental, and hereditary factors. Cryptorchidism can result in infertility and increases risk for testicular tumors. Testicular descent from abdomen to scrotum occurs in 2 distinct phases: the transabdominal phase and the inguinoscrotal phase (summary by Gorlov et al., 2002).

Abnormally small penis. At birth, the normal penis is about 3 cm (stretched length from pubic tubercle to tip of penis) with micropenis less than 2.0-2.5 cm.

An abnormal restriction of fetal growth with fetal weight below the tenth percentile for gestational age.

A deficiency or slowing down of growth pre- and postnatally.

Arnold-Chiari type I malformation refers to a relatively mild degree of herniation of the posteroinferior region of the cerebellum (the cerebellar tonsils) into the cervical canal with little or no displacement of the fourth ventricle. It is characterized by one or both pointed (not rounded) cerebellar tonsils that project 5 mm below the foramen magnum, measured by a line drawn from the basion to the opisthion (McRae Line)

Underdevelopment of the anterior pituitary gland.

A type of anemia characterized by increased size of erythrocytes with increased mean corpuscular volume (MCV) and increased mean corpuscular hemoglobin (MCH).

Hemoglobin F (HbF) contains two globin alpha chains and two globin gamma chains. It is the main form of hemoglobin in the fetus during the last seven months of intrauterine development and in the half year of postnatal life. In adults it normally makes up less than one percent of all hemoglobin. This term refers to an increase in HbF above this limit. In beta thalassemia major, it may represent over 90 percent of all hemoglobin, and in beta thalassemia minor it may make up between 0.5 to 4 percent.

A reduced number of hematopoietic cells present in the bone marrow relative to marrow fat.

A reduced count of megakaryocytes.

Dysplasia in the erythroid lineage, which presents with a variety of morphological changes in the bone marrow, including nuclear budding or irregular nuclear contour in erythroblasts.

A decreased rate of skeletal maturation. Delayed skeletal maturation can be diagnosed on the basis of an estimation of the bone age from radiographs of specific bones in the human body.

An abnormally low number of neutrophils in the peripheral blood.

A decreased functionality of the gonad.

An elevated concentration of follicle-stimulating hormone in the blood.