Case Report: Two New Cases of Chromosome 12q14 Deletions and Review of the Literature

Case Report: Intellectual disability and borderline intellectual functioning in two sisters with a 12p11.22 loss

Multiple genome sequencing studies have identified genetic abnormalities as major causes of severe intellectual disability (ID). However, many children affected by mild ID and borderline intellectual functioning (BIF) lack a genetic diagnosis because known causative ID genetic mutations have not been identified or the role of genetic variants in mild cases is less understood. Genetic variant testing in mild cases is necessary to provide information on prognosis and risk of occurrence. In this study, we report two sibling patients who were 5 years 9 months old and 3 years 3 months old and presented to the hospital due to developmental delay. Clinical assessment and chromosomal microarray analysis were performed. The patients were diagnosed with mild intellectual disability (ID) and borderline intellectual functioning (BIF). Genetic analysis identified a loss of 12p11.22, including the OVCH1-AS1, OVCH1, and TMTC1 genes, which was the only variant that occurred in both sisters. Identical variants were found in their father with probable BIF. Neither patient presented any brain structural abnormalities or dysmorphism, and no exogenous factors or parenting problems were reported. Thus, loss of 12p11.22 may be associated with our patients' cognitive impairment. The OVCH1, OVCH1-AS1 and TMTC1 variants identified in this study are the most likely disease-causing genes in the sisters. Our findings may expand as yet limited knowledge on mild ID and BIF causative variants, which would further support the diagnosis even if the severity is mild.

The benefit of rhGH therapy in a Chinese child with 12q14 microdeletion syndrome: a case report

OBJECTIVES

The 12q14 microdeletion syndrome is a rare genetic condition characterized by intrauterine growth restriction, proportionate short stature, failure to thrive, and intellectual disability. Few reports have discussed the therapeutic aspect of patients with 12q14 microdeletion syndrome. Herein, we report the first case of 12q14 microdeletion patient treated with rhGH without growth hormone deficiency.

CASE PRESENTATION

The patient presented with feeding difficulties during infancy, failure to thrive, intellectual disability and subtle dysmorphic facial features. The patient first visited the clinic at 5 years and 3 months, his height was 91.4 cm (-4.9 SD) and weight 10.0 kg (-2.86 SD). The growth hormone level was within the normal range. Bone radiological testing revealed no significant abnormalities. Genetic analysis identified a 6.97 Mb deletion at the chromosome 12q14.1-q14.3 region in the proband. Recombinant human growth hormone therapy was initiated, which lasted for 12 months, and the new height was 101.0 cm (-4.0 SD) and weight 12.0 kg (-3.6 SD).

CONCLUSIONS

This report first showed that patient with 12q14 microdeletion, although without growth hormone deficiency, can benefit from human growth hormone therapy.

Fetal Nasal Bone Hypoplasia in the Second Trimester as a Marker of Multiple Genetic Syndromes

Nasal bone hypoplasia is associated with a trisomy of chromosome 21, 18 or 13. Nasal bone hypoplasia can also be seen in other, rarer genetic syndromes. The aim of the study was to evaluate the potential of nasal bone hypoplasia, in the second trimester of pregnancy, as a marker of fetal facial dysmorphism, associated with pathogenic copy number variation (CNV). This retrospective analysis of the invasive tests results in fetuses with nasal bone hypoplasia, after excluding those with trisomy 21, 18 and 13. In total, 60 cases with nasal bone hypoplasia were analyzed. Chromosomal aberrations were found in 7.1% of cases of isolated nasal bone hypoplasia, and in 57% of cases of nasal bone hypoplasia with additional malformations. Additionally, in four of nine cases with non-isolated nasal bone hypoplasia but normal CMA results, a monogenic disease was diagnosed. Non-isolated hypoplastic nasal bone appears to be an effective objective marker of fetal facial dysmorphism, associated with pathogenic CNVs or monogenic diseases. In isolated cases, chromosomal microarray testing can be of additional value if invasive testing is performed, e.g., for aneuploidy testing after appropriate counseling.