Results Summary

What was the research about?

Galactosemia is a group of rare, inherited health problems. Babies with galactosemia have problems breaking down galactose, a sugar in milk. Babies with the most severe type of galactosemia get sick and may die if they drink breast milk or milk-based formula. Even if they don’t drink milk, they may have developmental complications when they are older. Developmental complications include problems moving, speaking, learning, hearing, or getting along with people.

Duarte galactosemia, or DG, is a less serious type of galactosemia. In DG, babies can break down some but not all of the galactose in milk. Few studies have looked at the risks of DG. Doctors don’t know whether babies with DG can drink breast milk and milk-based formula safely or whether drinking milk will cause problems when these babies are older.

In this study, the research team looked at whether

  • Children with DG have more developmental complications than their siblings without DG
  • Children with DG who drank breast milk or milk-based formula when they were babies have more developmental complications than children with DG who drank low-galactose formula

What were the results?

Children with DG didn’t have more developmental complications than their siblings without DG.

Children with DG who drank breast milk or milk-based formula didn’t have more developmental complications than children with DG who drank low-galactose formula.

Who was in the study?

The study included 206 children ages 6 to 12 with DG from 17 states and Washington, DC. Of the children with DG, 40 percent drank breast milk or milk-based formula as babies, and 60 percent drank low-galactose formula. The study also included 144 siblings of these children. The siblings were in the same age range but didn’t have DG. Of all the children, 90 percent were white, 2 percent were black, and 5 percent were another race; 3 percent were Hispanic. Because of the genetics of DG, most children with DG are white. The average age was nine, and 53 percent were boys.

What did the research team do?

The research team asked parents or guardians of children with DG to fill out a survey. The survey asked about

  • Their children’s health and diet, including whether they drank milk before age one
  • Special educational help children received before age three
  • Other children in the family without DG who could be in the study

Next, the research team checked children for developmental complications. The team tested the children’s abilities to move, speak, learn, hear, and get along with people. Team members also did genetic tests to make sure which children did and didn’t have DG.

Parents of children with DG, doctors, and people from advocacy groups worked with the research team on the study.

What were the limits of the study?

Parents or guardians may not have been able to accurately remember their children’s health and diet as babies. Also, results may have differed if the research team had tested children older than 12.

Future research could look at whether children with DG have other kinds of health problems. Researchers could also look at children older than the children in this study.

How can people use the results?

Doctors and parents can use the results when thinking about whether to avoid breast milk and milk-based formula for babies with DG.

Final Research Report

View this project's final research report

Journal Citations

Peer-Review Summary

Peer review of PCORI-funded research helps make sure the report presents complete, balanced, and useful information about the research. It also assesses how the project addressed PCORI’s Methodology Standards. During peer review, experts read a draft report of the research and provide comments about the report. These experts may include a scientist focused on the research topic, a specialist in research methods, a patient or caregiver, and a healthcare professional. These reviewers cannot have conflicts of interest with the study.

The peer reviewers point out where the draft report may need revision. For example, they may suggest ways to improve descriptions of the conduct of the study or to clarify the connection between results and conclusions. Sometimes, awardees revise their draft reports twice or more to address all of the reviewers’ comments. 

Peer reviewers commented and the researchers made changes or provided responses. Those comments and responses included the following:

  • The reviewers asked why the researchers did not conduct biochemical assays of enzyme and metabolite levels or strive to correlate the levels of such markers to developmental outcomes. The researchers said they did not do such tests to avoid subjecting children in the study to a needle stick, which the researchers felt was not necessary. They used saliva to collect DNA to confirm the children’s diagnoses. The researchers noted that prior research implies that the children with Duarte galactosemia would all have normal levels of a key metabolite at their ages of 6 to 12, regardless of diet.
  • The reviewers asked why the report did not discuss dietary exposure to galactose and not correlate galactose exposure to outcomes. The researchers said that they collected galactose exposure as a binary variable based on parent reports of their children’s diet when they were 2 to 12 months old. This enabled the largest number of cases to be available for comparison. However, the researchers noted that if they had seen any evidence of difference in outcomes between children who were exposed or not exposed to galactose, they would have attempted to analyze the issue further.  Since no difference was observed, the researchers did not perform any further analysis.

Conflict of Interest Disclosures

Project Information

Judith L. Fridovich-Keil, PhD
Emory University
$2,529,857 *
Intervention and Outcomes in Duarte Galactosemia

Key Dates

April 2015
January 2020

Study Registration Information

Final Research Report

View this project's final research report.

Journal Articles


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Last updated: October 18, 2023