Everett and Clementine From Colorado
Clementine was born in February 2025 in Denver, Colorado. Our third baby, but first little girl, we were overjoyed to have a daughter to complete our family. Clementine’s big brothers, Everett (5.5 years old) and Oliver (3 years old), anxiously awaited her arrival and have always adored their little sister. The pregnancy and delivery were smooth and uncomplicated. Clementine breastfed well from the start and began gaining weight quickly. While in the post-partum wing of the hospital, Clementine received her first newborn
screening at 24 hours old and again at around 2.5 weeks old during her 2-week check-up at the pediatrician. Having already had 2 babies pass their newborn screens and Clementine seemingly a perfectly healthy and normal baby, we knew the drill and didn’t think much of it.
Two weeks passed, and nothing seemed out of the ordinary. We were settling into life with a newborn, toddler, and preschooler, and all the chaos that comes with it. On a Friday evening when Clementine was 4 weeks old, we received a call from her pediatrician. Clementine’s newborn screen was abnormal, and we needed to bring her to the Children’s Hospital right away for bloodwork to confirm the results. We, of course, immediately panicked and began furiously Googling what conditions were included in Colorado’s newborn screening. We took her for bloodwork the following day, which revealed a homocysteine level of 153.9 mcmol/L and a methionine level of 736 nmol/L. At the time, we did not know what this meant other than that the levels were WAY beyond the normal range outlined in the test results. After more furious Googling, we realized Clementine likely had a metabolic condition we had never heard of—homocystinuria.
By Monday morning, we were frantic for more information. What did this mean? Was she in immediate danger? Was there treatment? A cure? What do we do?! That day, we were contacted by a Genetic Counselor with the Metabolic Clinic at Children’s Hospital. She confirmed what we suspected – Clementine had a condition called homocystinuria and needed to be seen by the Metabolic Clinic team right away. We met with the Metabolic team the following day, who confirmed Clementine’s diagnosis. We learned that our other children had a 25% chance of having HCU. But both Everett and Oliver had passed their newborn screenings without issue! Weren’t they in the clear? No, they weren’t.
We got the boys’ blood drawn right away to test their homocysteine levels. Oliver’s was 5.1 mcmol/L and in the normal range. Everett’s homocysteine was an astounding 222.7 mcmol/L. When we saw the results, my heart plummeted into my stomach. I felt sick. How could this have happened? Everett was tested as a newborn and passed! We were devastated. Distraught. Furious! We had missed the chance to treat Everett from birth, and now he would suffer more adverse impacts from the condition for the rest of his life.
The reason Everett was not flagged for HCU in his newborn screen is because Colorado’s threshold for identifying HCU in the newborn screening process was too high when he was born. Between the time Everett was born (2019) and Clementine was born (2025), Colorado lowered the threshold substantially. As a result, Everett was missed in newborn screening, but Clementine was caught. Colorado is a two-screen state (1 of 10 in the US), which means babies are first screened at 24 hours old. If a baby is flagged in the first screen, the baby is re-tested again at 8-14 days of age.
The two-screen process is very important because it allows a very low methionine cut off since the babies initially flagged will be re-screened and will trigger an abnormal finding only if the second screening shows out of range methionine levels. This is a crucial aspect of the newborn screen process for HCU, as newborn babies simply don’t have high enough methionine levels to meet a high threshold when they are first born.
As for Colorado, the state began checking for HCU in the newborn screen in 2006. From July 2006 to November 2021, newborns in Colorado were flagged for HCU in the first screen only if their methionine was 100 umol/L or higher. During this period, no newborns with HCU were identified through newborn screening. This included Everett, whose first newborn screen measured a methionine level of 83 umol/L. Because his methionine was below the 100 umol/L threshold, his screen was deemed normal and his methionine was not measured again on his second screen. Consequently, Everett was missed by newborn screening.
In November 2021, the Colorado Department of Public Health and Environment reduced the methionine cut-off in the first newborn screen to 47 umol/L, but still no babies were flagged for HCU.
CDPHE then lowered the methionine cut-off even further, to 33 umol/L, in August 2022. With this new threshold, 2 newborns were finally flagged for HCU through newborn screening. One of these babies was our daughter Clementine, whose first newborn screen in February 2025 showed a methionine level of 70 umol/L. Because her methionine was above the 33 umol/L threshold, Clementine was re-tested at her 2-week pediatrician appointment, which showed her methionine had climbed to a whopping 616 umol/L. It was at this point that CDPHE reached out to the Metabolic Clinic, who in turn contacted our pediatrician so that we could have Clementine undergo diagnostic bloodwork at 4 weeks old.
Clementine is the first newborn baby in Colorado with HCU flagged through Colorado’s newborn screening process. Until Clementine was born in February 2025, no babies with a methionine below 100umol/L with HCU had ever been caught in newborn screening in Colorado, including our son Everett. While Clementine was flagged and began treatment for HCU before she was 6 weeks old, Everett was missed and, therefore, wasn’t diagnosed or treated for HCU until he was 5.5 years old. Everett will bear the consequences of the later diagnosis his whole life. In fact, had Clementine not been born, we likely wouldn’t have known Everett had HCU for years and we suspect the journey to obtaining a diagnosis would have been long and difficult. While we are so grateful for Clementine’s early diagnosis, our story is a reminder that states can do better in their newborn screening for HCU. States can, and have, lowered newborn screen thresholds so that babies with HCU can be found! Thanks to Colorado lowering their threshold, Clementine and Everett were able to be diagnosed and treated for HCU.
In terms of Everett’s and Clementine’s treatment for HCU, neither are b6 responsive. In addition to their formula, they both take betaine twice daily and methyl folate once daily. Both have been very responsive to the low-protein diet. We are happy to report that Everett’s and Clementine’s homocysteine levels are now in the 30s.
As for how Everett is doing, he is a happy, energetic, smart, and funny kid! He starts kindergarten in August at our local elementary school. He loves Transformers, Legos, and construction. He began his low-protein diet in April of this year and has been an absolute champ with changing his diet. He is learning how to recognize protein count on nutrition labels and understands he can only have up to a certain amount of protein each day. He drinks his formula drink twice a day, mostly without complaint (!), and says his new diet makes him feel a lot better. With respect to the impacts of his untreated HCU, we are still in the process of having him evaluated. He is quite tall for his age. He got glasses (for nearsightedness) shortly before he was diagnosed with HCU, and we have since learned he also has some lens dislocation due to his untreated HCU. Everett also had a lot of trouble regulating his emotions, experienced brain fog, and engaged in more solo play when his HCU was untreated. Now that he is being treated, he seems generally happier, more clear headed, and has been playing a lot more in big groups. His coordination, balance, and gross motor skills have significantly improved since receiving treatment for HCU, and he learned to swim and ride a bike this summer. We are so proud of his progress!
![IMG_7776[12] (1)](https://hcunetworkamerica.org/wp-content/uploads/2025/08/IMG_777612-1.jpg "IMG_7776[12] (1)")
As for Clementine, she is a smiley, happy 6-month-old. She loves rolling over and recently started sleeping through the night. Her favorite thing to do is watch her brothers play and you can tell she can’t wait to be a big kid so she can join in the fun. She drinks a special HCU baby formula (made without methionine) mixed with regular baby formula – in specified quantities so that she gets just enough methionine to grow properly. She started eating solids a few weeks ago and is a big fan of all the fruit purees.
Both Clementine and Everett are doing very well! We know our journey with HCU has only just begun, but are grateful we were able to get their homocysteine levels within a manageable range relatively quickly.
We are hopeful there will one day be a cure and, until then, are doing the best we can under the circumstances and staying positive. We are lucky to work with the amazing Metabolic team at Children’s Hospital Colorado, and to only be a short car ride away from the Metabolic Clinic. We are hopeful Clementine’s and Everett’s HCU diagnosis story will shed light on the importance of newborn screening and demonstrate that lowering the screening threshold can and will make a difference in the lives of children born with HCU!
