Congenital Anatomic Defects Quiz

anatomic defects that are mostly present at birth and some may not be clinically apparent until years later

What year of birth is the most common cause of mortality of congenital anomalies?

Refers to the process of organ and tissue development

Morphogenesis can be impaired by a variety of what errors?

• represent PRIMARY errors of morphogenesis
• involves an INTRINSICALLY abnormal developmental process

Malformations can be a result of

one or more extra digits

fusion of digits

Cleft lip is what malformation syndrome

severe and essentially lethal malformation, wherein the midface structures are fused or ill-formed; in almost all cases, this degree of external dysmorphogenesis is associated with severe internal anomalies such as maldevelopment of the brain and cardiac defects

SECONDARY destruction of an organ or body region that was previously normal in development and arise from an EXTRINSIC disturbance in morphogenesis and may be caused by a variety of environmental agents. NOT HERITABLE

• classic example of disruption
• rupture of amnion with resultant formation of “bands” that encircle, compress, or attach to parts of the developing fetus

• also arise from an extrinsic disturbance in morphogenesis
• involve localized or generalized compression of the growing fetus by abnormal biomechanical forces

• serve as the most common underlying factor of deformations
• between the 35th-36th week of gestation, rapid increase in the size of the fetus outpaces the growth of the uterus

Maternal factors that increase the likelihood of excessive compression

Fetal or placental factors that increase the likelihood of excessive compression

cascade of anomalies triggered by 1 initiating aberration, may be explained by a single localized aberration in organogenesis (malformation, disruption, deformation) → cause secondary effects in other organs

chronic leakage of amniotic fluid d/t rupture of amnion -uteroplacental insufficiency d/t maternal hypertension or severe toxemia renal agenesis

Oligohydramnios

• constellation of congenital anomalies that cannot be explained on the basis of a single, localized, initiating defect
• most often caused by a single etiologic agent (e.g., viral infection, chromosomal abnormality) which simultaneously affects several tissues

complete absence of an organ and its associated primordium

absence of an organ that occurs d/t failure of growth of the existing primordium

absence of an opening of a hollow visceral organ (e.g., trachea, intestine)

incomplete development or decreased size of an organ with decreased number of cells

enlargement of an organ d/t increased number of cells

abnormal organization of cells

Arise from gametogenesis (not familial) o Examples:

• Down Syndrome and other trisomies
• Turner Syndrome
• Klinefelter syndrome

o underlie major malformations o characterized by mendelian inheritance

• most common form of short limb dwarfism
• gain-of-function mutations in fibroblast growth factor receptor 3 (which is a negative regulator of bone growth)

Holoprosencephaly

• most common form of short limb dwarfism
• gain-of-function mutations in fibroblast growth factor receptor 3 (which is a negative regulator of bone growth)

Single gene mutations (2-10%)

Maternal/placental infections

• infection extends from shortly before conception to the 16th week of gestation
• Hazard greater in the FIRST 8 weeks than in the second 8 weeks

cataracts, heart defects, deafness, mental retardation

CNS involvement, metal retardation, microcephaly, deafness, hepatosplenomegaly

• most common fetal viral infection
• highest at risk period: 2nd trimester of pregnancy

Maternal diseases states (6-8%)

• cause maternal hyperglycemia-induced fetal hyperinsulinemia or diabetic embryopathy
• results in fetal macrosomia (organomegaly + increased body fat and muscle mass)

• used as a tranquilizer
• causes 50-80% of limb abnormalities in exposed fetus

Mode of action of thalidomide

Most widely used teratogen and cause fetal alcohol syndrome

What pathways does alcohol disrupt?