9. Noonan syndrome due to autosomal recessive of LZTR1 gene: The first diagnosis and management in National Children’s Hospital

Can Thi Bich Ngoc, Vu Chi Dung

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Abstract

Noonan sydrome (NS) is an inherited multiple birth defect syndrome due to a dominant mutation in the genes such as PTPN11, SOS1, SOS2, RAF1, KRAS, NRAS, BRAF, SHOC2, CBL, RIT1LZTR1. Recombinant human GH (rhGH) has been shown to improve growth rate in NS patients. We describe the phenotype, genotype, and outcome of GH treatment in a patient with NS due to homozygous recessive variant of LZTR1 gene. The case is a 30-month-old female: height 82.5cm (< -2SD), 13kg, dysmorphic face with protruding forehead, flat nose bridge, upturned nose, eyes far apart, protruding teeth with darkened enamel then gradually diminishing and detaching, short and webber neck, low hair growth, forearm curvature, heart regular, 3/6 systolic murmur, lung not rales, chest wide, abdomen tender. Investigation: karyotype 46, XX; X-ray bone age 12 months, Echocardiography: myocardium hypertrophy. Molecular genetics analysis showed homozygous recessive mutations of genes LZTR1 c.650A>C, p.E217A and parents are carriers of recessive heterozygous of gene LZTR1. After 29 months of GH treatment, her height increased by 15.5cm (-1.54SD). Thus, NS can be caused by autosomal recessive of LZTR1 gene and initially GH treatment is effective in improving height.

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References

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