People with<unk> 's typically begin learning language at an ordinary pace, but by the age of 3–4 they experience a regression in mental and physical development, such as mild low muscle tone resulting in elongated faces and rapid loss in the normal growth of the head (microcephaly). Small testes and short stature are also known to commonly occur.
Renpenning's syndrome
Wartenberg's syndrome
Banti's syndrome
Liddle's syndrome
Villaret's syndrome
Frey's syndrome
Grisel's syndrome
Bertolotti's syndrome