Monitoring a Child with Heterozygous LZTR1 Variant

Introduction to LZTR1-Associated Conditions

The American Academy of Pediatrics recommends implementing surveillance for schwannomatosis starting at age 15-19 years with baseline brain and spine MRI, then every 2-3 years, in children with a heterozygous LZTR1 variant, while monitoring for Noonan syndrome features clinically at every well-child visit 1, 2

The American Heart Association recommends performing baseline echocardiogram at diagnosis to evaluate for pulmonary valve stenosis or hypertrophic cardiomyopathy in children with a heterozygous LZTR1 variant 1
The American Academy of Pediatrics recommends plotting height, weight, and head circumference at every well-child visit on standard growth curves to evaluate for proportionate short stature and relative macrocephaly characteristic of Noonan syndrome 1
The American Academy of Pediatrics recommends assessing developmental milestones at each visit, noting any delays in motor or cognitive development in children with a heterozygous LZTR1 variant 1
The American Academy of Pediatrics recommends examining for characteristic facial features, such as hypertelorism with down-slanting palpebral fissures, ocular ptosis, low-set posteriorly rotated ears, and broad neck with low posterior hairline, in children with a heterozygous LZTR1 variant 3

The American Society of Hematology recommends not performing routine complete blood counts in asymptomatic children with a heterozygous LZTR1 variant, but obtaining CBC only if the child appears ill or has hepatosplenomegaly on examination 1

The National Comprehensive Cancer Network recommends baseline MRI brain and spine at age 15-19 years to establish tumor burden before typical symptom onset in children with a heterozygous LZTR1 variant 2
The National Comprehensive Cancer Network recommends repeating MRI brain and spine every 2-3 years thereafter, or increasing surveillance frequency if symptomatic 2

The American College of Medical Genetics and Genomics recommends avoiding routine brain MRI surveillance for tumors in asymptomatic young children with LZTR1 Noonan syndrome, as the brain tumor risk is less than 1% 1, 4

The American Academy of Neurology and the National Institute of Neurological Disorders and Stroke recommend monitoring for chronic pain patterns, particularly neuropathic pain, in patients with LZTR1 variants 5, 6
The American College of Medical Genetics and Genomics suggests that LZTR1 variants can present with isolated vestibular schwannomas, particularly in patients <25 years old, with a reported frequency of 2.9% in patients with apparently isolated vestibular schwannoma 5, 6, 7
The National Comprehensive Cancer Network advises maintaining high suspicion for LZTR1-related schwannomatosis even with unilateral vestibular schwannoma 5, 6
The American Society of Clinical Oncology recommends offering genetic counseling to discuss inheritance patterns, recurrence risks, and family testing in patients with LZTR1 variants 8
The American College of Medical Genetics and Genomics suggests testing at-risk family members if the variant is confirmed pathogenic 8