To assess growth, birth length and all subsequent measures (in inches) obtained during hospitalization and clinic visits will be recorded. Length of the child will be used to characterize growth over the course of the 3 year follow up time.

Measurements of electrolytes, including calcium, phosphate, magnesium, BUN and creatinine values will be used to evaluate the incidence, timing, and severity of electrolyte disturbances and the management of these disturbances in the neonatal period in relation to phenotypic group and to genotype. This outcome will be captured as a 'yes/no' for any or all of the above.

The incidence, severity timing, and causative organisms of systemic infections during neonatal hospital stays will be reviewed in relation to management, including skin care practices and nursing procedures (e.g., open bed vs. humidified isolette).

Clinical severity will be rated using a standardized instrument. The evolution of skin phenotype will be documented via serial standardized photography. Transepidermal Water Loss (TEWL) will be measured in some sites.

To determine the incidence and severity of development delays in relation to genotype, a development history will be obtained at each follow-up evaluation, including information regarding relevant interventions such as physical or occupational therapy. Physical examination at each visit will assess range of motion of digital and major limb joints. This outcome will be captured as a 'yes/no' for any or all of the above.