A 2005 study reported that "there is no scientific background to support the alleged oversized penis in black people".A study of 253 men from Tanzania found that the average stretched flaccid penis length of Tanzanian males is 11.5 cm (4.53 inches) long, smaller than the worldwide average, stretched flaccid penis length of 13.24 cm (5.21 inches), and average erect penis length of 13.12 cm (5.17 inches).A 2016 study of 248 Korean men identified the average erect penis length to be 13.53 cm (5.33 in). A study of 115 men from Nigeria found that the average flaccid stretched penis length of Nigerian males is 13.37 cm (5.26 inches) long, which is near identical to the worldwide average, stretched flaccid penis length of 13.24 cm (5.21 inches) and average erect penis length of 13.12 cm (5.17 inches). A 2014 American study by Herbenick et al. of 1,661 sexually active men involving Asian American, Black American, White American, Pacific Islander/Hawaiian, and Native American men, found average 
racial differences in erect penile length and circumference to be generally less than one centimeter, with averages in length being: 14.14 cm (5.56 inches) for Asian Americans, 14.66 cm (5.77 inches) for Black Americans, 14.88 cm (5.85 inches) for Pacific Islanders/Hawaiians, 12.86 cm for Native Americans (5.06 inches), and 14.18 cm (5.58 inches) for White Americans (And in circumference: Asians 12.10 cm, Blacks 12.29 cm, Pacific Islanders 11.88 cm, Native Americans 11.36 cm, and Whites 12.25 cm).
Early psychomotor deterioration: decreased activity and lethargy in the first weeks; never sit; feeding problems - failure to thrive; visual failure (nystagmus noted) by 6 months; initial hypotonia; later spasticity with pyramidal signs; secondary microcephaly develops; decerebrate rigidity by 1 year and death by age 1–2 years (due to pneumonia and respiratory failure); some have hyperacusis. Macular cherry-red spots in 50% by 6–10 months; corneal opacities in some
Facial dysmorphology: frontal bossing, wide nasal bridge, facial edema (puffy eyelids); peripheral edema, epicanthus, long upper lip, microretrognathia, gingival hypertrophy (thick alveolar ridges), macroglossia
Hepatomegaly by 6 months and splenomegaly later; some have cardiac failure
Skeletal deformities: flexion contractures noted by 3 months; early subperiosteal bone formation (may be present at birth); diaphyseal widening later; demineralization; thoracolumbar vertebral hypoplasia and beaking at age 3–6 months; kyphoscoliosis. *Dysostosis multiplex (as in the mucopolysaccharidoses)
10–80% of peripheral lymphocytes are vacuolated; foamy histiocytes in bone marrow; visceral mucopolysaccharide storage similar to that in Hurler disease; GM1 storage in cerebral gray matter is 10-fold elevated (20–50-fold increased in viscera)
Galactose-containing oligosacchariduria and moderate keratan sulfaturia
Morquio disease Type B: Mutations with higher residual beta-galactosidase activity for the GM1 substrate than for keratan sulfate and other galactose-containing oligosaccharides have minimal neurologic involvement but severe dysostosis resembling Morquio disease type A (Mucopolysaccharidosis type 4). Late infantile/Juvenile GM1
Onset of late infantile GM1 is typically between ages 1 and 3 years. The juvenile form may be diagnosed into childhood. Some children live into adolescence or early adulthood.