Anomalous inheritance in a kindred with split hand, split foot malformation

Area of Science:

• Genetics
• Medical Genetics
• Developmental Biology

Background:

• Split hand, split foot malformation (SHSF) is a rare congenital limb anomaly.
• Autosomal dominant inheritance is the typical pattern observed in SHSF.
• Unusual pedigrees challenge conventional genetic models.

Purpose of the Study:

• Investigate the genetic basis of SHSF in a South African family with an atypical pedigree.
• Explore potential explanations for non-standard inheritance patterns.
• Provide recommendations for genetic counseling and monitoring.

Main Methods:

• Pedigree analysis of a South African family exhibiting SHSF.
• Exclusion of common inheritance models like new mutation, germinal mosaicism, and autosomal recessive inheritance.
• Hypothesizing alternative genetic mechanisms such as unstable premutations or reduced penetrance.

Main Results:

• The studied family displayed an unusual inheritance pattern where unaffected individuals produced affected offspring.
• Standard genetic explanations (new mutation, germinal mosaicism, autosomal recessive inheritance) were deemed unlikely.
• The findings suggest complex genetic factors, possibly involving unstable premutations or non-penetrance due to inhibiting factors.

Conclusions:

• The inheritance of SHSF in this family deviates from typical autosomal dominant patterns.
• Unstable premutations or non-penetrance are proposed as plausible explanations for the observed phenomenon.
• Prenatal ultrasound monitoring is recommended for unaffected relatives of SHSF individuals.