Adolescent development in males with Down syndrome.

We investigated growth features, development of primary and secondary sex characteristics, and specified pituitary and testicular hormone levels in 46 male adolescents and young adults with Down syndrome. Their mean height age was significantly less than and their mean bone age was slightly more than their chronological age. The subjects' secondary sex characteristics followed the same developmental pattern noted in youngsters without Down syndrome. Penile length and circumference and testicular volume of our patients with Down syndrome were not statistically different from those of normal adolescents. Follicle-stimulating hormone, luteinizing hormone, and testosterone levels in our study population were similar to those reported for normal adolescents during sexual maturation.

X-linked recessive myotubular myopathy: I. Clinical and pathologic findings in a family.

Four neonatal deaths in one family were due to X-linked myotubular myopathy. The characteristic alterations in muscle, described in three cases, are marked fiber hypotrophy, size variability, and the presence of internal nuclei or pale areas. The diagnosis can be verified only by obtaining a careful genetic history. Previous occurrence of male neonatal death or stillbirth, or of hypotonia and respiratory insufficiency, is critical in the identification of suspected cases. There is morphologic justification for retaining the name "myotubular myopathy" to distinguish this X-linked disorder from other congenital conditions involving muscle weakness that have similar morphologic features.

Juvenile nephronophthisis with blindness in a three-month-old infant. Senior's syndrome associated with relative parathyroid insufficiency.

Juvenile nephronophthisis is a slowly progressive renal disease with onset in infancy, characterized by impaired renal concentrating ability. The combination of juvenile nephronophthisis and tapeto-retinal degeneration, renal-retinal dystrophy, may cause blindness in infancy, and renal failure in the first decade of life. This syndrome has not been previously described as a cause of renal failure in young infants. We report an infant who presented at three months of age with blindness and renal insufficiency. In addition, this infant had a disproportionate degree of hypocalcemia and hyperphosphatemia compatible with relative parathyroid gland insufficiency. We propose that this was due to an inability of this infant's parathyroid glands to undergo compensatory hypertrophy, rather than a specific defect in parathyroid function associated with renal-retinal dystrophy.