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).

Abnormal position of urethral meatus on the ventral penile shaft (underside) characterized by displacement of the urethral meatus from the tip of the glans penis to the ventral surface of the penis, scrotum, or perineum.

Hypertrophic cardiomyopathy (HCM) is defined by the presence of increased ventricular wall thickness or mass in the absence of loading conditions (hypertension, valve disease) sufficient to cause the observed abnormality.

Increased size of the heart, clinically defined as an increased transverse diameter of the cardiac silhouette that is greater than or equal to 50% of the transverse diameter of the chest (increased cardiothoracic ratio) on a posterior-anterior projection of a chest radiograph or a computed tomography.

Atrial septal defect (ASD) is a congenital abnormality of the interatrial septum that enables blood flow between the left and right atria via the interatrial septum.

A ventricular septal defect that is confluent with and involves the membranous septum and is bordered by an atrioventricular valve, not including the type 3 VSDs.

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

Smaller than normal size according to sex and gestational age related norms, defined as a weight below the 10th percentile for the gestational age.

Dysplasia and dysgenesis of the corpus callosum are nonspecific descriptions that imply defective development of the corpus callosum. The term dysplasia is applied when the morphology of the corpus callosum is altered as a congenital trait. For instance, the corpus callosum may be hump-shaped, kinked, or a striped corpus callosum that lacks an anatomically distinct genu and splenium.

A decrease in the level of N-acetyl aspartate in the brain identified by magnetic resonance spectroscopy (MRS).

An increase in the level of lactate in the brain identified by magnetic resonance spectroscopy (MRS).

A reduction in erythrocytes volume or hemoglobin concentration.

An abnormal buildup of lactic acid in the body, leading to acidification of the blood and other bodily fluids.

Diminished amniotic fluid volume in pregnancy.

A reduction in the activity of the mitochondrial respiratory chain complex I, which is part of the electron transport chain in mitochondria.