HUMAN HEREDITY AS REVEALED BY PEDIGREES 449 



White forelock White patch of hair in front 



Hypotrychosis Hairlessness associated with lack of 



teeth 

 Pattern baldness Partly sex-limited 



Eyes: 



Front of iris pigmented (eyes black, 



brown, hazel, etc.) Dominant over lack of pigment in 



front of iris (blue eyes) 



Hereditary cataract Opacity of lens 



Night-blindness, when not 



sexdinked Inability to see in dim light 



Displaced lens Causing defective vision 



Glaucoma Swelling of eyeball due to internal 



pressure 



Coloboma Cpen suture of the iris 



Pigmentary degeneration of retina Causing blindness 



Skeleton and Muscles: 



Brachydactyly Digits lacking one joint 



Polydactyly Extra digits 



Syndactyly Fused or webbed digits 



Symphalangy Fused joints of digits, stiff fingers 



Split hand Palm cleft to the wrist 



Lobster claw No digits but thumb 



Exostoses Abnormal outgrowths of long bones 



Brittle bones Bones very fragile 



Absence of palmaris longus muscle Lack of a certain muscle in palm of 



hand 



Muscular atrophy Partially dominant 



Body Build: 



Achondroplasy Dwarfs with short, stout limbs, nor- 

 mal body and head 



Short stature Partly dominant over tallness 



Obesity, not due to glandular 



defects Partially dominant 



Nervous System and Kidneys: 



Huntington's chorea A type of St. Vitus' dance 



Diabetes insipidus Partially dominant 



Diabetes mellitus Partially dominant 



B. AUTOSOMIC RF.SESSTVE CHARACTERS 



Albinism Lack in pigment in skin and hair — 



sometimes pink eyes 



Ateleosis True dwarfs, body small with parts 



in normal proportions 



Cretinism Dwarfism due to hereditary thyroid 



deficiency 



