RESUMEN
B-cell acute lymphoblastic leukemia (B-ALL) is one of the most common childhood cancers worldwide. Although most cases are sporadic, some familial forms, inherited as autosomal dominant traits with incomplete penetrance, have been described over the last few years. Germline pathogenic variants in transcription factors such as PAX5, IKZF1, and ETV6 have been identified as causal in familial forms. The proband was a 7-year-old Mexican girl diagnosed with high-risk B-ALL at five years and 11 months of age. Family history showed that the proband's mother had high-risk B-ALL at 16 months of age. She received chemotherapy and was discharged at nine years of age without any evidence of recurrence of leukemia. The proband's father was outside the family nucleus, but no history of leukemia or cancer was present up to the last contact with the mother. We performed exome sequencing on the proband and the proband's mother and identified the PAX5 variant NM_016734.3:c.963del: p.(Ala322LeufsTer11), located in the transactivation domain of the PAX5 protein. The variant was classified as probably pathogenic according to the ACMG criteria. To the best of our knowledge, this is the first Mexican family with an inherited increased risk of childhood B-ALL caused by a novel germline pathogenic variant of PAX5. Identifying individuals with a hereditary predisposition to cancer is essential for modern oncological practice. Individuals at high risk of leukemia would benefit from hematopoietic stem cell transplantation, but family members carrying the pathogenic variant should be excluded as hematopoietic stem cell donors.
RESUMEN
We present an unusual Mexican patient affected with mucopolysaccharidosis type IIIB (MPS IIIB; also called Sanfilippo B syndrome, MIM #252920) bearing clinical features that have not previously been described for MPS IIIB (growth arrest, hypogonadotropic hypogonadism, and congenital heart disease). Chromosomal microarray analysis was useful in identifying runs of homozygosity at 17q11.1-q21.33 and supporting the diagnosis of an underlying autosomal recessive condition. Sanger sequencing of NAGLU (17q21.2, MIM*609701) allowed us to identify a pathogenic homozygous p.(Arg234Cys) genotype. This NAGLU allele could be related to that previously described in an Iberian MPS IIIB founder haplotype; results from the polymorphic marker D17S800 and rs2071046 led us to hypothesize that it may have been introduced to Mexico through the Spanish settlement. The analysis of a clinical exome sequencing ruled out other monogenic etiologies for the previously undescribed clinical MPS IIIB manifestations. Our findings contribute to further delineating the MPS IIIB phenotype and suggest possible phenotype-genotype correlations.
RESUMEN
OBJECTIVE: Rhabdomyomas are the most common type of prenatal cardiac tumors. When isolated, 50% to 70% are related to the tuberous sclerosis complex (TSC). The aim of this study was to reinforce the importance of additional clinical data in patients with prenatal heart tumors. METHODS: From 2010 to 2017, 10 prenatally detected cardiac tumors were referred to the Genetics Department, and a complete family history was taken. Postnatal echocardiographic and full clinical evaluation were completed. Next generation sequencing (NGS) of the TSC1 and TSC2 genes was performed. RESULTS: The 10 cases were postnatally confirmed as rhabdomyomas. Four de novo and four family cases were detected, and only one patient was previously aware of the TSC diagnosis. Molecular analysis by NGS was performed in four patients with three TSC2 mutations, two of which were previously reported and one not. DISCUSSION: Prenatal cardiac tumors are associated with TSC in 60% of cases. Prenatal diagnosis of cardiac tumors permits a further analysis of family members using the fetus as a clue for familial disease diagnosis.
